Maiheur Experiment Station - Oregon State...

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05.E550. 1062op. 2

DOES NOT CIRCULATEOregon State UniversityReceived on: 06—30—05

Special report

Special Report 1062July 2005

Maiheur Experiment StationAnnual Report 2004

Oregon State I Agricultural

UNIVERSITY ExperimentStation

For additional copies of this publication

Clinton C. Shock, SuperintendentMaiheur Experiment Station595 Onion AvenueOntario, OR 97914

For additional information, pleasecheck our website

http://www.cropinfo.net/

Agricultural Experiment StationOregon State University

Special Report 1062

July 2005

Malheur Experiment StationAnnual Report 2004

The information in this report is for the purpose of informing cooperators in industry, colleaguesat other universitities, and others of the results of research in field crops. Reference to products andcompanies in this publication is for specific information only and does not endorse or recommendthat product or company to the exclusion of others that may be suitable. Nor should information andinterpretation thereof be considered as recommendations for application of any pesticide. Pesticidelabels always should be consulted before any pesticide use.

Common names and manufacturers of chemical products used in the trials reported here arecontained in Appendices A and B. Common and scientific names of crops are listed in Appendix C.Common and scientific names of weeds are listed in Appendix D. Common and scientific namesof diseases and insects are listed in Appendix E.

CONTRIBUTORS AND COOPERATORS

MALHEUR EXPERIMENT STATION SPECIAL REPORT

2004 RESEARCH

MALHEUR COUNTY OFFICE, OSU EXTENSION SERVICE PERSONNELJensen, Lynn ProfessorMoore, Marilyn InstructorPorath, Marni Assistant Professor

MALHEUR EXPERIMENT STATIONEldredge, Eric Faculty Research AssistantFeibert, Erik Senior Faculty Research AssistantIshida, Joey Bioscience Research TechnicianJones, Janet Office SpecialistRansom, Corey V. Assistant Professor of Weed ScienceRice, Charles Faculty Research AssistantPereira, Andre Visiting ProfessorSaunders, Lamont Bioscience Research TechnicianShock, Clinton C. Professor, Superintendent

MALHEUR EXPERIMENT STATION, STUDENTSFlock, Rebecca Research AideHoxie, Brandon Research AideIshida, Jessica Research AideLinford, Christie Research AideNelson, Kelby Research AideSaunders, Ashley Research AideShock, Cedric Research AideSullivan, Susan Research Aide

OREGON STATE UNIVERSITY, CORVALLIS, AND OTHER STATIONSBafus, Rhonda Faculty Research Assistant, MadrasBassinette, John Senior Faculty Research Assistant, Dept. of Crop and Soil ScienceCharlton, Brian Faculty Research Assistant, Kiamath FallsHane, Dan Potato Specialist, HermistonJames, Steven Senior Research Assistant, MadrasKarow, Russell Professor, Dept. of Crop and Soil ScienceLocke, Kerry Associate Professor, Klamath FallsMosley, Alvin Associate Professor, Dept. of Crop and Soil ScienceRykbost, Ken Professor, Superintendent, Klamath Falls

OTHER UNIVERSITIESBrown, Bradford Associate Professor, Univ. of Idaho, Parma, IDFraisse, Clyde Research Engineer, Washington State Univ., Prosser, WAGallian, John Professor, Univ. of Idaho, Twin Falls, IDHoffman, Angela Professor, Univ. of Portland, Portland, ORHutchinson, Pamela Assistant Professor, Univ. of Idaho, Aberdeen, IDLove, Steve Professor, Univ. of Idaho, Aberdeen, IDMohan, Krishna Professor, Univ. of Idaho, Parma, IDMorishita, Don Associate Professor, Univ. of Idaho, Twin Falls, IDNeufeld, Jerry Associate Professor, Univ. of Idaho, Caldwell, IDNissen, Scott Associate Professor, Colorado State Univ., Ft. Collins, CONovy, Rich Research Geneticist/Potato Breeder, USDA, Aberdeen, IDO'Neill, Mick Superintendent, New Mexico State Univ., Farmington, NMReddy, Steven Extension Educator, Univ. of Idaho, Weiser, ID

OTHER PERSONNEL COOPERATING ON SPECIAL PROJECTSAnderson, Brian Clearwater Supply, Inc., Othello, WAArchuleta, Ray Natural Resource Conservation Service, Ontario, ORBosshart, Perry Professional Research Consultant, Farmington, MECalbo, Adonai G. Embrapa, Brasilia, DF, BrazilCamp, Stacey Amalgamated Sugar Co., Paul, IDEaton, Jake Potlatch, Boardman, ORErstrom, Jerry Malheur Watershed Council, Ontario, ORFeuer, Lenny Automata, Inc., Nevada City, CAFutter, Herb Malheur Owyhee Watershed Council, Ontario, ORHansen, Mike M.K. Hansen Co., East Wenatchee, WAHawkins, Al Irrometer Co., Inc., Riverside, CAHill, Carl Owyhee Watershed Council, Ontario, ORHuffacker, Bob Amalgamated Sugar, Nyssa, ORJones, Ron Oregon Department of Agriculture, Ontario, ORKameshige, Brian Cooperating Grower, Ontario, ORKameshige, Randy Cooperating Grower, Ontario, ORKlauzer, Jim Clearwater Supply, Inc., Ontario, ORKomoto, Bob Ontario Produce, Ontario, ORLeiendecker, Karen Oregon Watershed Enhancement Board, La Grande, ORLund, Steve Amalgamated Sugar Co., Twin FaIls, IDMartin, Jennifer Coordinator, Owyhee Watershed Council, Ontario, ORMatson, Robin Englehard Corp., Yakima, WAMcKeIIip, Robert Cooperating Grower, Nampa, IDMittlestadt, Bob Clearwater Supply, Inc., Othello, WAMurata, Warren Cooperating Grower, Ontario, ORNakada, Vernon Cooperating Grower, Ontario, ORNakano, Jim Malheur Watershed Council, Ontario, ORPage, Gary Malheur County Weed Supervisor, Vale, ORPenning, Tom Irrometer Co., Inc., Riverside, CAPhillips, Lance Soil and Water Conservation District, Ontario, ORPogue, Bill Irrometer Co., Inc., Riverside, CAPoihemus, Dave Andrews Seed Co., Ontario, ORPratt, Kathy Malheur Owyhee Watershed Council, Ontario, OR

TABLE OF CONTENTS (continued)

Soybean Performance in Ontario in 2004 124

POTATO

Potato Variety Trials 2004 128

Potato Tuber Bulking Rate and Processing Quality of Early Potato Selections --- 141

Planting Configuration and Plant Population Effects on Drip-irrigated UmatillaRusset Potato Yield and Grade 156

A Single Episode of Water Stress Reduces the Yield and Grade of RangerRusset and Umatilla Russet Potato 166

Irrigation System Comparison for the Production of Ranger Russet and UmatillaRusset Potato 173

Development of New Herbicide Options for Weed Control in Potato Production - 177

SUGAR BEETS

Sugar Beet Variety 2004 Testing Results 186

Kochia Control with Preemergence Nortron® in Standard and Micro-rateHerbicide Programs in Sugar Beet 194

Timing of Dual Magnum® and Outlook® Applications for Weed Control in SugarBeet 199

Comparison of Calendar Days and Growing Degree-Days for SchedulingHerbicide Applications in Sugar Beet 203

WHEAT AND SMALL GRAINS

2004 Winter Elite Wheat Trial 208

SOIL MOISTURE MONITORING

Automatic Collection, Radio Transmission, and Use of Soil Water Data 211

Use of Irrigas® for Irrigation Scheduling for Onion Under Furrow Irrigation 223

YELLOW NUTSEDGE BIOLOGY AND CONTROL

Factors Influencing Vapam® Efficacy on Yellow Nutsedge Tubers 230

Yellow Nutsedge Growth in Response to Environment 236

Yellow Nutsege Control in Corn and Dry Bean Crops 245

Chemical Fallow for Yellow Nutsedge Supression Following Wheat Harvest 250

OTHER PERSONNEL COOPERATING ON SPECIAL PROJECTS (continued)Richardson, Phil Oregon Dept. of Environmental Quality, Pendleton, ORSimantel, Gerald Novartis Seed, Longmont, COStadick, Chuck Simplot Grower Solutions, CaIdwell, IDStander, J. R. Betaseed, Inc., Kimberly, IDStewart, Kevin T-Systems International, Kennewick, WATaberna, John Western Laboratories, Inc., Parma, IDVogt, Glenn J. R. Simplot Co., Caldwell, IDWagstaff, Robert Cooperating Grower, Nyssa, ORWalhert, Bill Amalgamated Sugar, Ontario, ORWeidemann, Kelly Malheur Watershed Council, Ontario, ORYoder, Ron DuPont Crop Protection, Boise, ID

GROWERS ASSOCIATIONS SUPPORTING RESEARCHIdaho Alfalfa Seed Growers AssociationIdaho-Eastern Oregon Onion CommitteeIdaho Mint CommissionMalheur County Potato GrowersNyssa-Nampa Beet Growers AssociationOregon Alfalfa Seed CommissionOregon Alfalfa Seed Growers AssociationOregon Potato CommissionOregon Wheat Commission

PUBLIC AGENCIES SUPPORTING RESEARCHAgricultural Research FoundationMalheur County Soil and Water Conservation DistrictNatural Resource Conservation ServiceOregon Department of Environmental QualityOregon Department of AgricultureOregon Watershed Enhancement BoardU.S. Environmental Protection Agency 319 ProgramUSDA Cooperative State Research, Education, and Extension ServiceWestern Sustainable Agriculture Research and Extension

COMPANY CONTRIBUTORSABI Alfalfa, Inc. Summerdale, Inc.Advanced Agri-Tech SyngentaAllied Seed Cooperative T-Systems InternationalAmerican Crystal Sugar Co. UAP NorthwestAmerican Takii, Inc. ValentAMVAC W-L ResearchBASFBayer CropScienceBejo Seeds, Inc.Betaseed, Inc.Clearwater Supply, Inc.Crookham Co.D. Palmer Seed Co., Inc.Dairyland ResearchDeKaIb Genetics Corp.Dorsing Seeds, Inc.Dow AgrosciencesDuPontESI Environmental SensorsFMC Corp.Forage GeneticsFresno Valves & Castings, Inc.Geertson Seed Co.Global GeneticsGooding Seed Co.Gowan Co.Hotly Sugar Corp.Irrometer Co., Inc.M.K. Hansen Co.MonsantoNelson IrrigationNetafim Irrigation, Inc.Nichino America, Inc.Novartis Seeds, Inc.Nunhems USA, Inc.PioneerPotlatchRispens Seeds, Inc.Rohm and HaasSeed SystemsSeed WorksSeedex, Inc.Seminis Vegetable Seeds, Inc.Simplot Co.Streat Instruments, New Zealand

TABLE OF CONTENTS

WEATHER

2004 Weather Report I

ALFALFA

Third Year Results of the 2002-2006 Drip-irrigated Alfalfa Forage Variety Trial --- 8

CORN

Weed Control and Crop Response with Option® Herbicide Applied in Field Corn 14

MINT

Evaluations of Spring Herbicide Applications to Dormant Mint 18

ONION

2004 Onion Variety Trials 21

Pungency of Selected Onion Varieties Before and After Storage 30

Effect of Short-duration Water Stress on Onion Single Centeredness andTranslucent Scale 33

Treatment of Onion Bulbs with Surround® to Reduce Temperature and BulbSunscald 38

Effect of Onion Bulb Temperature and Handling on Bruising 45

Evaluation of Overwintering Onion for Production in the Treasure Valley,2003-2004 Trial 50

Weed Control in Onion with Postemergence Herbicides 54

Soil-active Herbicide Applications for Weed Control in Onion 65

Insecticide Trials for Onion Thrips (Thrips tabaci) Control - 2004 71

A Two-year Study on Varietal Response to an Alternative Approach forControlling Onion Thrips (Thrips tabaci) in Spanish Onions 77

A One-year Study on the Effectiveness of Oxamyl (Vydate L®) to Control Thripsin Onions When Injected into a Drip-irrigation System 89

Growers Use Less Nitrogen Fertilizer on Drip-irrigated Onion ThanFurrow-irrigated Onion 94

POPLARS AND ALTERNATIVE CROPS

Performance of Hybrid Poplar Clones on an Alkaline Soil 97

Micro-irrigation Alternatives for Hybrid Poplar Production 2004 Trial 106

Effect of Pruning Severity on the Annual Growth of Hybrid Poplar 118

TABLE OF CONTENTS (continued)

APPENDICES

A. Herbicides and Adjuvants 253

B. Insecticides, Fungicides, and Nematicides 254

C. Common and Scientific Names of Crops, Forages, and Forbs 255

D. Common and Scientific Names of Weeds 256

E. Common and Scientific Names of Diseases and Insects 256

2004 WEATHER REPORT

Erik B. G. Feibert and Clinton C. ShockMalheur Experiment Station

Oregon State UniversityOntario, OR

Introduction

Air temperature and precipitation have been recorded daily at the Malheur ExperimentStation since July 20, 1942. Installation of additional equipment in 1948 allowed forevaporation and wind measurements. A soil thermometer at 4-inch depth was added in1967. A biophenometer, to monitor degree days, and pyranometers, to monitor totalsolar and photosynthetically active radiation, were added in 1985.

Since 1962, the Maiheur Experiment Station has participated in the Cooperative WeatherStation system of the National Weather Service. The daily readings from the station arereported to the National Weather Service forecast office in Boise, Idaho.

Starting in June 1997, the daily weather data and the monthly weather summaries havebeen posted on the Malheur Experiment Station web site on the internet atwww.cropinfo.net.

On June 1, 1992, in cooperation with the U.S. Department of the Interior, Bureau ofReclamation, a fully automated weather station, linked by satellite to the NorthwestCooperative Agricultural Weather Network (AgriMet) computer in Boise, Idaho, begantransmitting data from Malheur Experiment Station. The automated station continuallymonitors air temperature, relative humidity, dew point temperature, precipitation, windrun, wind speed, wind direction, solar radiation, and soil temperature at 8-inch and20-inch depths. Data are transmitted via satellite to the Boise computer every 4 hoursand are used to calculate daily Malheur County crop water-use estimates. The AgriMetdatabase can be accessed through the internet at www.usbr.gov/pn/agrimet and is linkedto the Malheur Experiment Station web page at www.cropinfo.net.

Methods

The ground under and around the weather stations was bare until October 17, 1997,when it was covered with turigrass. The grass is irrigated with subsurface drip irrigation.The weather data are recorded each day at 8:00 a.m. Consequently, the data in thetables of daily observations refer to the previous 24 hours.

Evaporation is measured from April through October as inches of water evaporated froma standard 10-inch-deep by 4-ft-diameter pan over 24 hours. Evapotranspiration (ETa)for each crop is calculated by the AgriMet computer using data from the AgriMet weather

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station and the Kimberly-Penman equation (Wright 1 982). Reference evapotranspiration(ET0) is calculated for a theoretical 12- to 20-inch-tall crop of alfalfa assuming full coverfor the whole season. Evapotranspiration for all crops is calculated using ET0 and cropcoefficients for each crop. These crop coefficients vary throughout the growing seasonbased on the plant growth stage. The crop coefficients are tied to the plant growth stageby three dates: start, full cover, and termination dates. Start dates are the beginning ofvegetative growth in the spring for perennial crops or the emergence date for row crops.Full cover dates are typically when plants reach full foliage. Termination dates aredefined by harvest, frost, or dormancy. Alfalfa mean is calculated for an alfalfa cropassuming a 15 percent reduction to account for cuttings.

Wind run is measured as total wind movement in miles over 24 hours at 24 inches abovethe ground. Weather data averages in the tables refer to the years preceding and up to,but not including, the current year.

2004 Weather

The total precipitation for 2004 (11.98 inches) was higher than the 10-year (10.19 inches)and 60-year (10.16 inches) averages (Table 1). Precipitation in October was about threetimes the 10-year and 60-year averages. Total snowfall for 2004 (24 inches) was higherthan the 10-year (14.0 inches) and 61-year averages (18.2 inches) (Table 2).

The highest temperature for 2004 was 104°F on July 18 (Table 3). The lowest tempera-ture for the year was -1°F on January 5. The average maximum and minimum airtemperatures for March were substantially higher than the 10-year and 60-yearaverages. March 31 reached 80°F.

March had the highest number of growing degree days (50° to 86°F) for that month since1986, when measurements were started (Table 4, Fig. 1). The total number of degreedays in the above-optimal range in 2004 was close to the average (Table 5).

The months of May through December had total wind runs lower than the 10-yearaverage (Table 6). Total pan-evaporation for 2004 was close to the 10-year and 56-yearaverages (Table 7). Total accumulated for all crops in 2004 was close to the 10-yearaverage (Table 8).

The average monthly maximum and minimum 4-inch soil temperatures in 2004 wereclose to the 10-year and 37-year averages (Table 9).

The last spring frost (�32°F) occurred on April 16, 13 days earlier than the 28-yearaverage date of April 29; the first fall frost occurred on October 24, 19 days later than the28-year average date of October 5 (Table 10). The 191 frost-free days was the longestfrost-free period over the last 14 years.

No other weather records were broken in 2004 (Table 11).

2

References

Wright, J.L. 1982. New evapotranspiration crop coefficients. J. Irrig. Drain. Div., ASCE108:57-74.

Table 1. Monthly precipitation at the Maiheur Experiment Station, Oregon StateUniversity, Ontario, OR, 1991-2004.

Year Jan Feb Mar Apr May Jun Jul Augnches

Sep Oct Nov Dec Totali

1991 0.59 0.44 0.88 0.81 1.89 1.09 0.01 0.04 0.35 101 1.71 0.43 9.251992 0.58 1.36 0.25 0.74 0.21 1.43 0.36 0.01 0.09 0.95 1.15 1,51 8.641993 2.35 1.02 2.41 2.55 0.70 1.55 0.18 0.50 0.00 0.80 0.64 0.60 13.301994 1.20 0.57 0.05 1.02 1.62 0.07 0.19 0.00 0.15 1.23 2.46 1.49 10.051995 2.67 0.28 1.58 1.16 1.41 1.60 1.10 0.13 0.07 0.57 0.88 2.56 14.011996 0.97 0.86 1.03 1.19 2.39 0.12 0.32 0.31 0.59 0.97 1.18 2.76 12.691997 2.13 0.17 0.25 0.66 0.67 0.86 1.40 0.28 0.40 0.43 1.02 0.94 9.211998 2.26 1.45 0.95 1.43 4.55 0.36 1.06 0.00 1.00 0.04 1.07 1.11 15.281999 1.64 2.50 0.59 0.23 0.28 1.02 0.00 0.09 0.00 0.40 0.49 0.73 7.972000 2.01 2.14 0.97 0.72 0.28 0.26 0.03 0.06 0.39 1.74 0.38 0.66 9.642001 1.15 0.41 1.11 0.70 0.37 0.64 0.32 0.00 0.10 0.68 1.33 1.00 7.782002 0.77 0.27 0.49 0.77 0.09 0.60 0.14 0.10 0.36 0.29 0.44 1.86 6.182003 1.46 0.48 0.99 1.12 1.52 0.24 0.36 0.11 0.15 0.02 0.86 1.47 8.782004 1.82 1.54 0.25 0.98 1.70 0.43 0.13 0.64 0.56 2.03 0.93 0.97 11.98

10-yravg 1.63 0.91 0.80 0.90 1.32 0.58 0.49 0.11 0.32 0.64 1.04 1.46 10.1960-yravg 1.35 0.95 0.95 0.81 1.04 0.77 0.26 0.38 0.48 0.69 1.15 1.33 10.16

Table 2. Annual snowfall totals at the MaiheurUniversity, Ontario, OR, 1991-2004.

Experiment Station, Oregon State

inches

7.5 15.5 36.0 32.0 15.0 14.5 5.8 14.6 13.2 13.8 15.5 11.5 4.5 24.0 14.0 18.2

Table 3. Monthly air temperature, Malheur Experiment Station, Oregon State University,Ontario, OR, 2004.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm

Highest 44 33 51 34 80 44 79 49 85 56 99 63 104 72 100 69 95 58 80 57 56 43 52 41

Lowest 13 -1 29 11 43 25 52 32 56 37 70 46 80 49 69 46 63 38 47 29 37 19 30 18

2004 avg 31 20 38 24 62 36 67 41 72 47 84 53 93 60 89 58 78 48 67 41 46 31 41 28

10-yr avg 38 25 46 27 56 32 64 37 72 45 81 51 93 59 91 55 81 47 66 36 48 29 38 24

60-yr avg 35 20 43 25 55 31 64 37 73 45 82 52 92 58 90 56 80 46 66 36 48 28 37 22

3

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 10-yr 61-yr

avg avg

Average "--- 2003 —•—-— 2004 1993

U-3500

co0

LC)

2500(I)

2000

1500

10:0

Day of year

Figure 1. Cumulative growing degree days (50-86°F) over time for selected yearscompared to 14-year average, Malheur Experiment Station, Oregon State University,Ontario, OR.

Table 4. Monthly total growing degree days (50-86°F), Malheur Experiment Station,Oregon State University, Ontario, OR, 1991-2004.Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

1991 0 13 16 124 212 389 776 718 436 194 1 0 2,8791992 0 13 106 202 482 574 639 704 385 174 4 0 3,2831993 0 23 81 423 358 464 524 408 252 6 0 2,5391994 0 2 92 189 369 523 794 774 509 144 2 0 3,3981995 0 29 32 106 293 433 680 588 472 101 3 1 2,7471996 0 5 53 135 243 446 805 658 364 194 18 2 2,9231997 4 0 81 117 419 509 661 706 481 157 20 0 3,1541998 0 2 52 112 68 571 802 749 515 151 16 4 3,0421999 2 43 72 329 459 683 703 416 184 30 0 2,921200 0 4 36 194 342 536 751 743 368 133 2 0 3,1092001 tJ 0 63 126 401 488 715 761 472 155 27 3,2082002 0 2 32 137 319 562 805 621 437 142 14 2 3,0732003 0 4 72 112 319 594 846 754 448 281 11 2 3,4432004 0 c 115 187 311 607 776 680 365 180 4 0 3,225

18-year avg IJ 6 54 150 324 514 727 686 436 173 13 1 3,064

4

74 148 221 295 369

Table 5. Monthly total degree days in the above-ideal (86 -1 04°F) range, MalheurStation, Oregon State University, Ontario, OR,Experiment

Year Apr May Jun Jul Aug Sep Oct Total

1991 0 0 2 41 36 4 0 83

1992 0 5 20 23 54 2 0 104

1993 0 4 4 2 11 5 0 26

1994 0 2 16 68 54 7 0 147

1995 0 0 4 23 22 7 0 56

1996 0 0 5 54 32 4 0 95

1997 0 4 0 27 31 5 0 67

1998 0 0 0 63 45 14 0 122

1999 0 1 2 21 16 1 0 41

2000 0 0 7 41 43 4 0 95

2001 0 5 7 25 45 4 0 86

2002 0 0 14 54 11 5 0 85

2003 0 5 9 74 36 5 0 130

2004 0 0 18 43 31 2 0 94

14-yr avg 0 2 7 41 34 6 0 90

Table 6. Wind-run daily totalsState University, Ontario, OR, 2004.

and monthly totals, Malheur Experiment Station, Oregon

Daily - Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

miles

Mean 54 74 67 75 43 45 35 34 46 31 32 24

Max. 170 201 175 164 118 120 90 64 137 124 136 120

Mm. 17 25 15 16 16 13 0 14 19 5 2 0

Annual total miles

2004 1,659 2,143 2,092 2,261 1,320 1,336 1,087 1,039 1,389 972 947 739

10-yraverage 1,573 1,942 2,500 2,512 2,293 1,932 1,723 1,685 1,554 1,798 1,616 1,91256-yraverage 2,150 1937 1,572 1,477 1,332 1,253 1,290

Table 7. Pan-evaporation totals, Malheur Experiment Station, Oregon State University,Ontario, OR, 2004.

Totals April May Jun Jul Aug Sep Oct TotalDaily inchesMean 0.25 0.24 0.36 0.39 0.30 0.22 0.13Max. 0.41 0.35 0.48 0.57 0.42 0.45 0.28Mm. 0.10 0.12 0.23 0.12 0.07 0.08 0.00

Annual inches2004 7.25 7.51 10.66 12.09 9.23 6.55 3.82 57.11

10-yravg 6.05 8.45 9.75 11.61 10.70 7.38 4.43 58.2756-yravg 5.61 7.72 8.94 11.15 9.64 6.32 3.28 51.78

5

1991-2004.

Table 8. Total accumulated reference evapotranspiration (ETa) and cropevapotranspiration (EL) (acre-inches/acre), Maiheur Experiment Station, Oregon StateUniversity, Ontario, OR, 1992-2004.

Year Reference Alfalfa Winter Spring Sugar Onion Potato Dry Field 1st year 2nd year 3rd yearET (mean) grain grain beet bean corn poplar poplar + poplar

1992 53.7 44.4 26.9 27.9 36.1 30.3 28.8 21.3 29.8 -- -- --

1993 51.9 36.4 21.3 22.7 29.3 24.1 22.8 17.9 23.7 -- -- --

1994 57.6 40.6 21.3 22.6 34.5 29.5 28.2 21.1 27.7 -- -- —

1995 49.6 37.1 18.9 22.2 29.0 26.7 23.6 16.7 23.7 -- -- --

1996 52.8 39.8 22.3 24.1 32.9 27.2 26.3 19.5 25.7 -- -- --

1997 55.2 41.5 23.8 25.3 33.4 28.0 26.6 19.7 25.1 -- -- --

1998 55.0 40.7 21.3 23.9 32.4 28.2 26.2 21.0 27.9 23.9 37.1 44.0

1999 58.6 43.9 25.0 26.4 33.7 28.9 26.5 21.7 28.5 24.3 37.8 45.5

2000 58.7 45.5 26.0 25.7 38.3 32.0 29.5 24.1 30.6 24.9 38.9 47.1

2001 57.9 43,8 25.5 27.2 34.8 30.3 27.4 21.4 29.1 23.7 37.0 44.7

2002 58.8 41.7 25.9 28.7 35.2 30.4 27.7 21.9 27.8 23.6 36.7 44.4

2003 54.2 44.1 27.5 31.7 39.1 32.0 32.4 22.5 29.6 24.3 37.9 45.9

2004 52.8 43.5 27.8 30.6 34.3 30.9 27.7 22.5 28.9 23.3 36.3 44.1

10-year 55.8 41.9 23.8 25.8 34.3 29.3 27.4 21.0 27.6 24.1 37.6 45.3average

Table 9. Monthly soil temperature at 4-inch depth, Malheur Experiment Station, OregonState University, Ontario, OR, 2004.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Max Mm Max Mm Max Mm Max Mm Max Mm Max Mm MaxMin Max Mm MaxMin Max Mm Max Mm Max Mm

°F

Highest 37 34 38 34 52 47 59 52 65 60 77 69 81 72 81 71 72 66 64 59 46 45 46 45Lowest 31 30 32 29 37 36 47 43 55 50 61 56 69 63 66 62 59 55 48 45 34 33 32 32

2004 avg 33 32 33 32 45 41 54 48 61 55 70 62 76 68 74 68 65 60 56 52 42 40 37 36

10-yr avg 35 34 38 35 46 41 55 47 65 56 73 64 80 70 78 70 70 63 57 52 44 41 36 3537-yr avg 33 32 38 34 49 40 59 47 71 57 80 66 87 73 85 72 75 63 59 51 44 40 35 33

6

Tab'e 10. Last andExperiment Station,

first frost (�32°F) dOregon State Univ

ates and numbeersity, Ontario,

r of frost-free days, MaiheurOR, 1990-2004.

YearDate of last frost Date of first frost Total frost-free days

Spring Fall

1990 May8 Oct7 152

1991 Apr30 Oct4 157

1992 Apr24 Sep14 143

1993 Apr20 Oct11 174

1994 Apr15 Oct6 174

1995 Apr16 Sep22 159

1996 May6 Sep23 140

1997 May3 Oct8 158

1998 Apr18 Oct17 182

1999 May11 Sep28 140

2000 May12 Sep24 135

2001 Apr29 Oct10 164

2002 May8 Oct12 157

2003 May19 Oct11 145

2004 April16 Oct24 191

1976-2003 Avg April 29 October 5 159

Table 11. Record weather events at the Malheur Experiment Station, Oregon StateUniversity, Ontario, OR.

Record event

Since

Greatest annual precipitation

Measurement Date

1943

16.87 inches 1983

Greatest monthly precipitation 4.55 inches May 1998

Greatest 24-hour precipitation 1.52 inches Sep 14, 1959

Greatest annual snowfall 40 inches 1955

Greatest 24-hour snowfall 10 inches Nov 30, 1975

Earliest snowfall 1 inch Oct 25, 1970

Highest air temperature 110°F July 22, 2003

Total days with maximum air temp. �100°F 17 days 1971

Lowest air temperature -26°F Jan 21 and 22, 1962

Total days with minimum air temp. �0°F

Since

Lowest soil temperature at 4-inch depth

Since

Highest yearly growing degree days

35 days 1985

1967

12°F Dec 24, 25, and 26, 1990

1986

3,446 degree days 1988

Lowest yearly growing degree days

Since

Highest reference evapotranspiration

2,539 degree days 1993

1992

58.8 inches 2002

7

THIRD YEAR RESULTS OF THE 2002-2006 DRIP-IRRIGATED ALFALFA FORAGEVARIETY TRIAL

Eric P. Eldredge, Clinton C. Shock, and Lamont D. SaundersMaiheur Experiment Station

Oregon State UniversityOntario, OR, 2004

Introduction

The purpose of this trial is to compare the productivity and hay quality of alfalfa varietiesin the Treasure Valley area of Malheur County. The trial also provides information aboutthe adaptation of alfalfa hay production to drip irrigation. In this trial, over 5 years, 10proprietary varieties are being compared to 2 public check varieties. This trial wasestablished with a portable sprinkler-irrigation system and then grown with a subsurfacedrip-irrigation system.

Methods

The trial was established on Owyhee silt loam where winter wheat was the previouscrop and alfalfa had not been grown for more than 10 years. Pathfinder (NelsonIrrigation Corp., Walla Walla, WA) drip tape (15 mil thick, 0.22 gal/mm/i 00-ft flow rate,12-inch emitter spacing) was shanked in at a depth of 12 inches on 30-inch spacingbetween the drip tapes. Plots were 5 ft wide by 20 ft long in a randomized completeblock design with each entry replicated five times. Further details of the establishmentof this trial were reported previously (Eldredge et al. 2003).

Gramoxone® at 2 pint/acre plus Sencor® at 1.5 pint/acre were applied for weed controlon March 11, 2004. No irrigations were applied before the first cutting in 2004. After thefirst cutting, irrigations were semi-automated using a valve controller (DIG Corp. Vista,CA) initially programmed to apply a 1-inch irrigation twice weekly, on Mondays andThursdays. Alfalfa crop evapotranspiration (ETa) was calculated based on datacollected by an AgriMet (U.S. Bureau of Reclamation, Boise, ID) weather stationlocated on the Malheur Experiment Station. Soil moisture was monitored by sixWatermark soil moisture sensors model 200SS (Irrometer Co. Inc., Riverside, CA)installed at 12-inch depth in the center of six alfalfa plots, midway between drip tapes.Sensors were connected to an AM400 data logger (M.K. Hansen, East Wenatchee,WA) equipped with a thermistor to correct soil moisture calculations for soiltemperature. Water applied was measured by a totalizing water meter on the inlet of theirrigation system. A rodenticide, Maki bromadiolone supercade bait (Liphatech, Inc.,Milwaukee, WI), was applied in rodent tunnels on July 22 with a gopher probe (EagleIndustries, Chatsworth, CA).

8

The alfalfa was harvested at bud stage on May 14, June 17, July 19, August 13, andSeptember 22, 2004. A 3-ft by 20-ft swath was cut from the center of each plot with aflail mower, and the alfalfa was weighed. Ten samples of alfalfa were hand cut fromborder areas of plots over the entire field on the same day just before each cutting,quickly weighed, dried in a forage drier at 140°F with forced air, and reweighed todetermine the average alfalfa moisture content at each cutting. Yield was reported astons per acre of alfalfa hay at 88 percent dry matter.

Samples of alfalfa from approximately 1 ft of row per plot were taken June 16, beforethe second cutting, to measure forage quality. The forage quality samples were dried,ground in a Wiley mill (Thomas Scientific, Swedesboro, NJ) to pass through a 1-mmscreen, subsampled, and sent to the Oregon State University Forage Quality Lab atKlamath Falls, Oregon, where they were reground in a UDY mill (UDY Corp., Ft. Collins,CO) to pass through a 0.5-mm screen. Near infrared spectroscopy (N IRS) was used toestimate percent dry matter, percent crude protein, percent acid detergent fiber (ADF),percent neutral detergent fiber (NDF), percent fat, and percent ash. Relative foragequality (RFQ) was calculated by the formula:

RFQ = (DM1 * TDNL)/ 1.23where:DM1 = dry matter intake (for alfalfa hay), andDM1 = (((0.120 * 1350)! (NDF/100)) + (NDFD 45) * 0.374) / 1350 * 100, andNDFD = dNDF48 / NDF * 100, anddNDF48 = digestible NDF as a percentage of dry matter, as determined by a 48-hour invitro digestion test,TDNL = total digestible nutrients [for legume (alfalfa hay)]TDNL = (NFC * 0.98) + (protein * 0.93) + (fat * 0.97 * 2.25) + ((NDF-2) * (NDFD!100))NFC 100- ((NDF -2) + protein + 2.5 + ash), and 1.23 was chosen as thedenominator to adjust the scale to match the RFV scale at 100 = full bloom alfalfa.

Quality standards based on REQ are: Supreme, REQ higherthan 185; Premium, REQ170-184; Good, RFQ 150-169; Fair, RFQ 130-149, and Low, REQ below 129. RFQestimates voluntary energy intake when the hay is the only source of energy andprotein for ruminants. Hay with a higher RFQ requires less grain or feed concentrate toformulate dairy rations.

Results and Discussion

Rodents chewed holes in the drip tape and continued to be a problem in this trial.During the winter, voles burrowed down to the drip tape and chewed holes that werefound and repaired at the first irrigation. The rodenticide applied in the vole tunnels waseffective until the grain crop adjacent to the alfalfa trial was harvested. After the grainharvest, a new population of voles gradually colonized the alfalfa trial. A gopher thatmoved into the trial was promptly exterminated.

9

Soil moisture was monitored at the 12-inch depth after first cutting (Fig. 1). After June 8,the soil remained uniformly moist in the —20 to —30 kPa (centibar) range for the rest ofthe irrigation season.

The total irrigation water applied was less than the season-long accumulated alfalfacrop evapotranspiration (Fig. 2). The irrigation system was turned off for harvestoperations and to repair leaks. Smaller irrigations, from 0.01 to 0.38 inch, were appliedon seven dates through the summer in order to check for leaks or following repairs tothe drip tape. Accumulated season-long alfalfa from March 5 to October 10 totaled43.38 inches, and the drip irrigation measured by the water meter, plus rain, totaled31 .81 inches or 73.3 percent of accumulated season-long alfalfa ETC.

The average third-year total hay yield was 7.9 ton/acre (Table 1). The first-cuttingaverage yield was 2.5 ton/acre, with 'SX1002A' 'Masterpiece', and 'SX1001A' yieldingamong the highest. In the second cutting 'Ruccus', Masterpiece, 'Tango', 'Orestan', and'Somerset' were among the highest yielding varieties. In the third cutting, Ruccus,'Lahontan', Masterpiece, Orestan, and Tango were among the highest yieldingvarieties. In the fourth cutting, Ruccus, Tango, Orestan, and Lahontan were among thehighest yielding. In the fifth cutting, Ruccus, 'Plumas', and Somerset were among thehighest yielding varieties. In total yield of five cuttings, Ruccus, with 8.4 ton/acre,Masterpiece, with 8.2 ton/acre, and Tango, SX1002A, and Orestan each with 8.0ton/acre, were among the highest yielding.

The crude protein averaged 25.6 percent in the second cutting, and ranged from 24.3percent for Orestan to 26.7 percent for Somerset. Acid detergent fiber, ADF, averaged26.7 percent. Neutral detergent fiber, NDF, averaged 31.2 percent. Relative foragequality averaged 245, with all varieties in the "Supreme" quality range. SX1005A,Plumas, Somerset, and Masterpiece produced hay with RFQ scores higher than 247.

Total hay production in the first 3 years averaged 18.3 ton/acre (Table 2). The varietiesRuccus, at 20.1 ton/acre; Tango, at 19.4 ton/acre; and Masterpiece, at 19.3 ton/acrewere among the highest yielding.

Information on the disease, nematode, and insect resistance of the varieties in this trialwas provided by the participating seed companies and/or the North American AlfalfaImprovement Council (Table 3). Most alfalfa varieties have some resistance to thediseases and pests that could limit hay production. Growers should choose varietiesthat have stronger resistance ratings for disease or pest problems known to be presentin their fields. The yield potential of a variety should be evaluated based onperformance in replicated trials at multiple sites over multiple years.

References

Eldredge, E.P, C.C. Shock, and L. D. Saunders. 2003. First year results of the 2002 to2006 alfalfa forage variety trial. Oregon State University Special Report 1048:14-17.Available online at www.cropinfo.net/AnnualReports/2002/B5aDripAlf02.htm

10

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Figure 1. Soil moisture in the drip-irrigated alfalfa variety trial during the 2004 growingseason, Maiheur Experiment Station, Oregon State University, Ontario, OR.

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40

35

30

.C 25C.)

20

15

10

Date, 2004

Figure 2. Accumulated irrigation applied plus rain compared to the AgriMet accumulatedevapotranspiration (ETa) for alfalfa grown for hay, Malheur Experiment Station, OregonState University, Ontario, OR 2004.

11

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Table 1. Alfalfa variety hay yields and second-cutting crude protein*, ADF*, NDF*, andrelative forage quality for 2004, Malheur Experiment Station, Oregon State University,Ontario, OR.

VarietyCutting date 2004 Crude

5/14 6/17 7/19 8/13 9/22 total protein ADFt NDFRelative

forage qualityton/acr& % of RFQ

Ruccus 2.4 1.4 2.0 1.2 1.3 8.4 26.0 27.0 31.5 239Masterpiece 2.7 1.3 1.9 1.1 1.2 8.2 25.1 26.1 30.7 251Tango 2.5 1.3 1.9 1.2 1.2 8.0 25.2 28.0 32.9 228SX1002A 2.9 1.2 1.7 1.1 1.2 8.0 25.1 27.4 32.3 233Orestan 2.4 1.3 1.9 1.2 1.2 8.0 24.3 29.0 34.2 213Lahontan 2.3 1.2 2.0 1.2 1.2 7.9 25.8 26.7 31.3 243Plumas 2.6 1.2 1.8 1.0 1.3 7.9 26.6 24.9 29.2 267SX1001A 2.7 1.2 1.7 1.0 1.2 7.9 25.4 26.3 31.2 244Somerset 2.4 1.3 1.8 1.1 1.3 7.9 26.7 26.1 30.3 253SX1003A 2.5 1.2 1.6 1.0 1.2 7.5 25.5 26.5 31.0 246SX1005A 2.5 1.1 1.7 1.0 1.1 7.4 26.4 25.1 29.1 271SX1004A 2.3 1.2 1.5 1.0 1.2 7.4 25.5 26.8 31.2 247Mean 2.5 1.2 1.8 1.1 1.2 7.9 25.6 26.7 31.2 245LSD (0.05) 0.29 0.09 0.18 0.07 0.10 0.47 1.27 1.74 2.26 23.7*Based on percent of dry weight. TADF: acid detergent fiber. neutral detergent fiber.

at 88 percent dry matter. dry weight.

Table 2. Alfalfa variety hay yields in the first 3 years of the 2002-2006variety trial, Malheur Experiment Station, Oregon State University,drip-irrigated alfalfa

Ontario, OR, 2004Yield

Variety 2002* 2003 2004 Cumulativeton/acreT

Ruccus 2.6 9.1 8.4 20.1Tango 2.5 9.0 8.0 19.4Masterpiece 2.4 8.7 8.2 19.3Somerset 2.4 8.5 7.9 18.8Orestan 2.2 8.4 8.0 18.7Plumas 2.6 8.1 7.9 18.5Lahontan 2.0 8.1 7.9 18.1SX1001A 2.1 8.0 7.9 18.0SX1002A 1.9 7.7 8.0 17.7SX1005A 2.4 7.7 7.4 17.5SX1004A 2.1 7.5 7.4 16.9SX1003A 2.0 7.0 7.5 16.5Mean 2.3 8.2 7.9 18.3LSD (0.05) 0.40 0.54 0.47 0.94*Two cuttings, 8/6 and 9/5/2002. TYield at 88 percent dry matter.

12

Table 3. Variety source, year of release, fall dormancy, and level of resistance to pestsand diseases for 12 alfalfa varieties in the 2002-2006 drip-irrigated forage variety trial,Maiheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Variety Source

Release

year FD*Pest Resistance ratingt

BW FW VW PRR AN SAA PA SN AP RKN

Orestan public 1934 R - - - - - - - - -

Lahontan public 1954 6 MR LR - LR - MR LR R - -

Tango Eureka Seeds 1997 6 MR HR HR HR HR HR HR MR - R

Plumas Eureka Seeds 1997 4 HR HR R HR HR R R HR R MR

Masterpiece SimplotAgribusiness

Somerset Croplan Genetics

2000

2000

4

3

HR HR

HR HR

R

HR

HR

HR

HR

HR

R -

R -

HR

R

R

HR

R

-

Ruccus Target Seed 2001 5 R HR R HR MR R R R - MR

Seedex - - - - - - - - - - - -

SX1002A Seedex - - - - - - - - - - - -

SX1003A Seedex - - - - - - - - - - - -

SX1004A Seedex - - - - - - - - - - - -

SX1005A Seedex - - - - - - - - - - - -

*FD: fall dormancy, BW: bacterial wilt, FW: Fusarium wilt, VW: Verticillium wilt, PRR: Phytophthora rootrot, AN: Anthracnose, SAA: spotted alfalfa aphid, PA: pea aphid, SN: stem nematode, AP: Aphanomyces,RKN: root knot nematode (northern).

tpest resistance rating: >50 percent = HR (high resistance), 31-50 percent = R (resistant),15-30 percent = MR (moderate resistance), 6-14 percent = LR (low resistance).

tFall Dormancy: 1 = Norseman, 2 = Vernal, 3 = Ranger, 4 = Saranac, 5 = DuPuits, 6 = Lahontan,7 = Mesilla, 8 = Moapa 69, 9 = CUF 101.

varieties, not released, pest resistance data not available.

13

WEED CONTROL AND CROP RESPONSE WITH OPTION® HERBICIDEAPPLIED IN FIELD CORN

Corey V. Ransom, Charles A. Rice, and Joey K. IshidaMaiheur Experiment Station


Introduction

Weed control is important in field corn production to reduce competition with the cropand to prevent the production of weed seed for future crops. Field trials wereconducted to evaluate Option® (foramsulfuron) herbicide applied alone and in variouscombinations for weed control and crop tolerance in furrow-irrigated field corn. Optionis a new postemergence sulfonylurea herbicide that controls annual and perennialgrass and broadleaf weeds in field corn. Option contains a safener that is intended toenhance the ability of corn to recover from any yellowing or stunting sometimesassociated with the application of sulfonylurea herbicides.

Materials and Methods

The soil was formed into 22-inch beds on May 10. Plots were sidedressed with 126 lbnitrogen (N), 14 lb sulfates, 3 lb zinc, 1 lb boron, 1 lb manganese, and 38 lb elementalsulfur/acre on May 11. Pioneer variety 'P-36N69' Roundup Ready® field corn wasplanted with a John Deere model 71 Flexi Planter on May 17. Seed spacing was oneseed every 7 inches. Plots were 7.33 by 30 ft and herbicide treatments were arrangedin a randomized complete block with four replicates. Herbicide treatments were appliedwith a C02-pressurized backpack sprayer calibrated to deliver 20 gal/acre at 30 psi.Crop response and weed control were evaluated throughout the growing season. Cornyields were determined by harvesting ears from 26-ft sections of the center 2 rows ineach 4-row plot on October 11. The harvested ears were shelled and grain weight andpercent moisture content were recorded. Grain yields were adjusted to 12 percentmoisture content. Data were analyzed using analysis of variance (ANOVA) andtreatment means were separated using Fisher's protected least significant difference(LSD) at the 5 percent level (P = 0.05).

Postemergence treatments of Option, Clarion®, or Roundup® were applied alone and incombinations with other herbicides and with or without preemergence (PRE) DualMagnum®. PRE applications were made May 21. Mid-postemergence (MP) treatmentswere applied to corn at the V4 growth stage on June 11, and late postemergencetreatments (LP) were applied to corn at the V6 growth stage on June 19. Option wasapplied with various additives as well as in combination with Distinct® or Callisto®.Option combinations were compared to Clarion applied alone and in combination withDistinct or to Roundup applied alone or following PRE Dual Magnum. The herbiciderates and combinations are shown in Table 1.

14


Control of pigweed species (i.e., Powell amaranth and redroot pigweed) ranged from 91to 100 percent on July23 and was similar among herbicide treatments. One exceptionwas the treatment with Option, Dyne-Amic®, and 32 percent N, which provided only 91percent control (Table 1). When Option was applied with Dyne-Amic and 32 percent Nor Quest®, common lambsquarters control also was lower than all other treatments.Clarion alone also provided less common lambsquarters control than all othertreatments except for Option applied with Dyne-Amic. Combinations of Option withDistinct or Callisto, and the combination of Clarion and Distinct provided among thebest common lamsquarters control. Common lambsquarters control was improvedwhen Roundup was applied following PRE Dual Magnum compared to Roundupapplied alone. Clarion alone provided the least hairy nightshade control, and thecombination of Clarion and Distinct also provided less hairy nightshade controlcompared to all other treatments except Option with Dyne-Amic and 32 percent N.There were no significant differences in kochia and barnyardgrass control amongtreatments.

Injury from herbicide treatments ranged from 0 to 14 percent on June 19 and was 4percent or less on July 2 (Table 2). Corn yields ranged from a low of 103 bu/acre withthe untreated control to a high of 194 bu/acre with the combination of Option andCallisto (Table 2). The treatment containing Option with Dyne-Amic and 32 percent Nhad lower yields than many of the other Option treatments and was likely due toreduced weed control with that treatment.

The selection of additives can significantly affect the efficacy of Option against pigweedspecies, common lambsquarters, and hairy nightshade. The addition of Distinct orCallisto to Option can significantly improve common lambsquarters control.

15

Table 1.Station,

WeedOregon

control with OptioState University,

n® herbiOntario,

cide applied in field corn, Malheur ExperimentOR, 2004.

I

Treatment Rate* Timingt

Weed controP

Pigweed C, lambs-spp* quarters

H. night-shade Kochia

Barnyard-grass

lb al/acrept/acre% v/v

0.033 + 1.5 + 3.0 MP 100 79 92 96 97

Option + MSO + AMS

Option + DYNE-AMIC +32% N

0.033 + 1.5 + 3.0 MP

0.033 + 0.25% +3.0

100 88 99 97 100

76 95 94

Option + MSO + QUEST 0.033 + 1.5 ÷2.5% MP 98 89 98 100 97

Clarion + MSO + 32% N 0.023 + 1.5+4 MP 98 61 52 98 99

Option + MSO + 32% N 0.033 + 1.5 +3.0 MP 99 89 94 100 97

Option + Distinct +MSO + 32% N

0.033 + 0.088 +1.5 + 3.0

MP 100 100 96 100 96


0.33 + 0.175 +1.5 + 3.0

MP 100 100 99 100 97

Clarion + Distinct +NlS + 32% N

0.023 + 0.088 +0.5% + 4.0

MP 100 97 73 100 100

Option + Callisto +MSO + 32% N

0.033 + 0.0625 +1.5 + 3.0

MP 99 100 97 100 98

Dual II MagnumOption + MSO + 32% N

1.60.033 + 1.5 + 3.0

PRELP

97 90 85 100 100

Option + MSO + AMS 0.033 + 1.5 +3 MP 99 88 97 99 96

Option + DYNE-AMIC +Quest

0.033 ÷ 0.25 % +0.25%

MP 97 48 88 99 100

Roundup Ultramax 0.58 MP 99 81 95 100 97

Dual II MagnumRoundup Ultramax +AMS

LSD (0.05) 3

*Herbicide rates are in lb ai/acre. Additive rates are in pt/acre or percent v/v.tApplication timings were preemergence (PRE) on May 21, mid-postemergence (MP) applied to corn at the V4rowth stage on June 11, and late postemergence (LP) to corn at the V6 growth stage on June 19.Pigweed species were a mixture of Powell amaranth and redroot pigweed.

control was evaluated July 23. The untreated control was not included in the ANOVA for weed control.

Option + MSO + 32% N

MP 91 45

1.60.58 + 3.0

PRELP

100 92

6

90 100 99

11 NS NS

16

Table 2. Injury and yield with Option® herbicide applied in field corn, MaiheurExperiment Station, Orecion State University. Ontario, OR, 2004.

Field corn

Treatment Rate* Timingt 6-19 7-2 Yields

lb al/acre 0/ bu/acre

Untreated control -- -- -- -- 103

Option + MSO + 32% N 0.033 + 1.5 + 3.0 MP 8 0 179

Option + MSO + AMS 0.033 + 1.5 + 3.0 MP 9 0 187

Option + DYNE-AMIC +32% N

0.033 + 0.25% +3.0

MP 5 0 157

Option + MSO + QUEST 0.033 + 1.5 +2.5% MP 10 0 192

Clarion + MSO + 32% N 0.023 + 1.5+4 MP 3 0 178

Option + MSO + 32% N 0.033 + 1.5 +3.0 MP 9 3 174


0.033 + 0.088 +1.5 + 3.0

MP 11 0 183


0.33 + 0.175 +1.5 + 3.0

MP 14 4 178

Clarion + Distinct +NIS+32%N

0.023 + 0.088 +0.5%+4.0

MP 6 1 189

Option + Callisto +MSO + 32% N

0.033 + 0.0625 +1.5 + 3.0

MP 5 0 194

Dual II MagnumOption + MSO + 32% N

1.60.033 + 1.5 + 3.0

PRELP

9 3 184

Option + MSO + AMS dry 0.033 + 1.5 +3 MP 9 0 178

Option + DYNE-AMIC +Quest

0.033 + 0.25% +0.25%

MP 1 0 178

Roundup Ultramax 0.58 MP 0 0 189

0 0 173

2 21

Dual II MagnumRoundup Ultramax +AMS

LSD (0.05) 4.5

*Herbicide rates are in lb ai/acre. Additive rates are in pt/acre or percent v/v. - --

tApplication timings were preemergence (PRE) on May 21 mid-postemergence (MP) applied to corn at the V49rowth stage on June 11, and late postemergence (LP) to corn at the V6 growth stage on June 19.

untreated control was not included in the ANOVA for percent injury.SCorn was harvested October 11 and yields were adjusted to 12 percent moisture content.

pt/acre% v/v

1.60.58 + 3.0

PRELP

17

EVALUATIONS OF SPRING HERBICIDE APPLICATIONS TO DORMANT MINT

Corey V. Ransom, Charles A. Rice, and Joey K. IshidaMalheur Experiment Station


Introduction

Weed control in mint is essential in order to maintain high mint oil yields and quality.Reducing competition from weeds may prolong the productive life of a mint stand.Herbicides are important tools for controlling weeds in mint. With the constant loss ofherbicides that are registered for use in mint, it is critical to identify replacements thatwill provide similar weed control. Several new herbicides that have recently becomeavailable or may be available in the near future have been tested in mint. This researchevaluated herbicides that have been used traditionally with new herbicide combinationscontaining some recently registered herbicides including Spartan® (sulfentrazone),Chateau

R

(flumioxazin), and Command® (clomazone).


Two trials were established to evaluate spring herbicide applications to dormant mint formint tolerance and weed control efficacy. One trial was established near Nampa, Idahoand the other near Nyssa, Oregon. Perennial weed problems and a poor mint standresulted in abandonment of the Oregon location. Herbicides that were evaluatedincluded a standard of Sinbar , Karmex , Stinger , and Prowl compared to variouscombinations that included Spartan, Chateau, and Command. Treatments wereapplied March 3, 2004 when mint was still mostly dormant. Herbicide treatments werearranged in a randomized block design with four replicates. Plots were 10 ft wide by 30ft long. Herbicides were applied with a C02-pressurized backpack sprayer calibrated todeliver 20 gal/acre at 30 psi. Visual evaluations of mint injury and weed control weremade throughout the season. Mint yield was determined by harvesting mint from 3from the center of each plot. After the mint fresh weight was recorded, a 20-lb sub-sample was taken and allowed to dry in burlap bags. Once samples were dry, mint oilwas extracted at the University of Idaho mint research still. Distillation was doneaccording to the Mint Industry Research Council (MIRC) protocol.


Only the treatment containing Command, Spartan, and Stinger caused significant mintinjury on April 27 (Table 1). The same combination with Spartan at a lower rate causedsignificantly less mint injury, as did the combination of Command, Spartan, andGramoxone®. By June 7, no significant injury was visible for any treatment. Pricklylettuce populations were variable, and variability among prickly lettuce control

18

evaluations resulted in no statistical differences among herbicide treatments. Kochiadensities were too low for visual control evaluation, but counts of all the kochia in eachplot revealed that all but two treatments significantly reduced kochia numbers comparedto the untreated check. The combination of Sinbar, Karmex, Stinger, and Chateau andthe combination of Command, Chateau, and Gramoxone did not significantly reducekochia numbers. Mint fresh weight and oil yields were strongly correlated with pricklylettuce control and kochia densities (Fig. 1). All treatments increased mint yieldcompared to the untreated control. The combination of Command, Chateau, andGramoxone produced lower mint fresh weight and oil yields than all other treatmentsexcept combinations of Command, Spartan, and Gramoxone, but had similar oil yieldscompared to the combination of Sinbar, Karmex, Singer, and Prowl.

35 160y=0.1558x+11.041

i R2=0.74131

Y0.647X+28.888

5 20

0 0 20 40 60 80 100 120

A Prickly lettuce control B Prickly lettuce control (%)

35 160

30801x2 + 0.3547x + 25.16k

140Y = -0.3947x2+2.0559x+ 86.721

• • R2 = 0.5266 . R2 = 0.4563

20

C Kochia (no./plot) D Kochia (no./plot)

Figure 1. Mint fresh hay and oil yield as influenced by prickly lettuce control (A and B) andkochia density (C and D) in Nampa, ID, Malheur Experiment Station, Oregon StateUniversity, Ontario, OR, 2004. For all regressions P < 0.0000.

19

*Treatments were applied March 3, 2004 to dormant mint.tHerbicide rates are lb ai/acre. NIS (nonionic surfactant, Activator 90) was applied at 0.25 percent V/V.

separation is based on transformed data. Raw data are presented.

Table 1. Mint injury and weed control from spring herbicide applications to dormantExperiment Station, Oregon State University, Ontario, OR, 2004

peppermint in Nampa, ID, Maiheur

Treatment* Ratet

Weed control Kochiadensityt

Mint yieldFresh Wt. OilMint injury Prickly lettuce

4-27 6-7 4-27 6-7 7-28 7-28 8-25lb/3 yd2

8-25lb/acrelb ai/acre 0/ no/plot

Untreated control -- - - - - - 13 a 8.7 28Sinbar + Karmex +Stinger + Prowl + NIS

0.6 + 0.8 +0.124 + 1.5 + 0.25%

3 5 84 86 87 2 b 19.5 82

Sinbar + Karmex +Stinger + Spartan + NIS

0.6 + 0.8 +0.124 + 0.188 + 0.25%

0 3 96 94 96 0 b 21.0 95

Sinbar + Karmex +Stinger + Chateau + NIS

0.6 + 0.8 +0.124 ÷ 0.125 + 0.25%

5 4 94 94 98 5 ab 20.8 96

Command + Spartan +Stinger + NIS

0.375 + 0.188 ÷0.124 ÷ 0.25%

21 5 81 84 90 0 b 21.0 103

Command + Chateau +Stinger + NIS

0.375 + 0.125 +0.124 + 0.25%

5 4 95 92 95 4 b 21.6 84

Command + Spartan +Gramoxone Extra + NIS

0.375 + 0.188 +0.375 + 0.25%

8 4 70 66 83 4 b 18.9 77

Command + Chateau +Gramoxone Extra + NIS

0.375 + 0.125 +0.375 + 0.25%

4 4 59 58 59 8 ab 15.1 58

Sinbar + Karmex +Stinger + Spartan + NIS

0.6 + 0.8 +0.124 + 0.125 + 0.25%

6 4 92 90 89 2 b 19.4 92

Command + Spartan ÷Stinger + NIS

0.375 + 0.125 +0.124 + 0.25%

9 5 91 89 94 1 b 22.2 97

Command + Spartan +Gramoxone Extra + NIS

0.375 + 0.125 +0.375 + 0.25%

4 5 76 60 78 0 b 19.0 74

Command + Spartan +Stinger + Buctril + NIS

0.375 + 0.125 +0.124 + 0.25 + 0.25%

3 5 83 86 93 1 b 20.6 96

LSD (0.05) 10 NS NS NS NS - 4.1 24

2004 ONION VARIETY TRIALS

Clinton C. Shock, Erik B. G. Feibert, and Lamont D. SaundersMaiheur Experiment Station

Lynn JensenMalheur County Extension Service


Krishna MohanUniversity of Idaho

Parma, ID

Introduction

The objective of the onion variety trials was to evaluate yellow, white, and red onionvarieties for bulb yield, quality, and single centers. Five early season yellow varietiesand one early season white variety were planted in March and were harvested andgraded in August. Forty-three full season varieties (33 yellow, 5 red, and 5 white) wereplanted in March, harvested in September 2004, and evaluated in January 2005.

Methods

The onions were grown on an Owyhee silt loam previously planted to wheat. Soilanalysis indicated the need for 60 lb nitrogen (N)/acre, 100 lb phosphate (P2O5)Iacre,70 lb sulfur/acre, 2 lb copper/acre, 7 lb zinc/acre, and 1 lb boron/acre, which wasbroadcast in the fall. In the fall of 2003, the wheat stubble was shredded, and the fieldwas disked, irrigated, ripped, moldboard-plowed, roller-harrowed, fumigated withTelone C-17® at 20 gal/acre, and bedded. A soil sample taken on May 20, 2004showed a pH of 7.3, 2 percent organic matter, 8 ppm nitrate-N, 37 ppm phosphorus,and 461 ppm potassium.

A full season trial and an early maturing trial were conducted adjacent to each other.Both trials were planted on March 19 in plots four double rows wide and 27 ft long. Theearly maturing trial had 6 varieties from 3 companies (Table 1) and the full season trialhad 43 varieties from 10 companies (Table 2). The experimental design for both trialswas a randomized complete block with five replicates. A sixth nonrandomized replicatewas planted for demonstrating onion variety performance to growers and seedcompany representatives.

Seed was planted in double rows spaced 3 inches apart at 9 seeds/ft of single row.Each double row was planted on beds spaced 22 inches apart with a customizedplanter using John Deere Flexi Planter units equipped with disc openers. The onionrows received 3.7 oz of Lorsban 1 per 1,000 ft of row (0.82 lb ai/acre), and the soilsurface was rolled on March 20. The field was irrigated on March 25. On March 31 the

21

field was sprayed with Roundup® at 24 oz/acre. Onion emergence started on April 5.On May 4, alleys 4 ft wide were cut between plots, leaving plots 23 ft long. From May 5through 8, the seedlings were hand thinned to a plant population of two plants/ft ofsingle row (6-inch spacing between individual onion plants, or 95,000 plants/acre). Thefield was sidedressed with 100 lb of N/acre as urea and cultivated on May 12. On June9 the field was sidedressed with 100 lb N/acre as urea.

The onions were managed to avoid yield reductions from weeds, pests, and diseases.Weeds were controlled with an application of Prowl® at 0.75 lb ai/acre on April 12 andon May 12, and an application of Goal® at 0.12 lb ai/acre, Buctril® at 0.12 lb ai/acre, andPoast® at 0.28 lb ai/acre on May 25. After lay-by the field was hand weeded asnecessary. Thrips were controlled with aerial applications of Warrior® on June 12,Warrior (0.03 lb ai/acre) plus Lannate® (0.4 lb ai/acre) on June 25, Warrior (0.03 lbai/acre) plus MSR®(0.5 lb ai/acre) on July 17, and Warrior (0.03 lb ai/acre) plus Lannate(0.4 lb ai/acre) on July 31.

The trial was furrow irrigated when the soil water potential at 8-inch depth reached -25kPa. Soil water potential was monitored by thirteen granular matrix sensors (GMS,Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside, CA)installed in mid-June below the onion row at 8-inch depth. Six sensors wereautomatically read three times a day with an AM-400 meter (Mike Hansen Co., EastWenatchee, WA). Seven sensors were automatically read hourly with a WatermarkMonitor (Irrometer Co., Inc.). The last irrigation was on August 20.

Onions in each plot were evaluated subjectively for maturity by visually rating thepercentage of onions with the tops down and the percent dryness of the foliage. Thepercent maturity was calculated as the average percentage of onions with tops downand the percent dryness. The early maturing trial was evaluated for maturity on August10 and the full season trial on August 24. The number of bolted onion plants in eachplot was counted.

Onions in each plot were evaluated subjectively for damage from iris yellow spot viruson August 11. Each plot was rated according to the number of leaves with symptomsper plant: 0 = no symptoms, 5 = at least 3 leaves with symptoms per plant.

Onions from the middle two rows in each plot in the early maturity trial were lifted onAugust 13, and topped by hand and bagged on August 17. On August20 the onionswere graded. The onions in the full season trial were lifted on September 8 to fieldcure. Onions from the middle two rows in each plot of the full season trial were toppedby hand and bagged on September 15. The bags were put in storage on September22. The storage shed was managed to maintain an air temperature as close to 34°F aspossible. Onions from the full season trial were graded out of storage on January 11and 12, 2005.

During grading, bulbs were separated according to quality: bulbs without blemishes (No.is), split bulbs (No. 2s), neck rot (bulbs infected with the fungus Botiytis all/i in the neck

22

or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold(bulbs infected with the fungus Aspergillus niger). The No. I bulbs were gradedaccording to diameter: small (<2.25 inches), medium (2.25-3 inches), jumbo (3-4inches), colossal (4-4.25 inches), and supercolossal (>4.25 inches). Bulb counts per 50lb of supercolossal onions were determined for each plot of every variety by weighingand counting all supercolossal bulbs during grading. The red varieties were evaluatedsubjectively during grading for exterior thrips damage during storage. The bulbs fromeach red variety plot were rated on a scale from 0 (no damage) to 10 (most damage)for the damage that was apparent on the bulb surface, without removing the outerscales.

In early September bulbs from one of the border rows in each plot of both trials wererated for single centers. Twenty-five consecutive onions ranging in diameter from 3.5 to4.25 inches were rated. The onions were cut equatorially through the bulb middle and,if multiple centered, the long axis of the inside diameter of the first single ring wasmeasured. These multiple-centered onions were ranked according to the diameter ofthe first single ring: "small double" had diameters less than 1 .5 inches, "intermediatedouble" had diameters from 1 .5 to 2.25 inches, and "blowout" had diameters greaterthan 2.25 inches. Single-centered onions were classed as a "bullet". Onions wereconsidered functionally single centered for processing if they were a "bullet" or "smalldouble."

Varietal differences were compared using ANOVA and least significant differences atthe 5 percent probability level, LSD (0.05).

Results

Varieties are listed by company in alphabetical order. The LSD (0.05) values at thebottom of each table should be considered when comparisons are made betweenvarieties for significant differences in performance characteristics. Differences betweenvarieties equal to or greater than the LSD value for a characteristic should exist beforeany variety is considered different from any other variety in that characteristic.

A few experimental varieties were named in 2004. Nunhems' 'SX 70000N' and 'SX70020N' were named 'Bandolero' and 'Montero', respectively. Seedworks' '6001' wasnamed 'Maverick'. Varieties are all listed by name in the results. The experimentalnumbers are useful for comparing results from previous years.

Iris Yellow Spot Virus RatingSubjective rating of damage from iris yellow spot virus for the early maturing varietiesranged from 0.68 for 'Renegade' to 1.84 for 'XON-0101' (Table 1). Subjective rating ofdamage from iris yellow spot virus for the full season varieties ranged from 0.82 for'T-433', 'Delgado', and 'PX 5299' to 1.92 for 'Export 151' (Table 3).

23

Early Maturity Trial, Five Yellow Varieties, One White VarietyThe percentage of "bullet" single centers averaged 20.6 percent and ranged from 0percent for 'XON-209W', a white variety, to 76.4 percent for Montero (Table 1). Thepercentage of onions that were functionally single centered averaged 45 percent andranged from 14.7 percent for XON-0101 to 95.2 percent for Montero. Montero had thehighest percentage of bullet and functionally single-centered bulbs in this trial.

Total yield averaged 849 cwtlacre and ranged from 721 cwtlacre for Montero to 971.4cwt/acre for 'Exacta' (Table 2). Exacta, XON-0101, and Renegade were among thehighest in total yield. Supercolossal-size onion yield averaged 25.6 cwtlacre andranged from 9.2 cwt/acre for XON-209W to 47.2 cwt/acre for Exacta. Exacta andXON-0101 were among the highest in yield of supercolossal bulbs. Not consideringsupercolossals, colossal-size onion yield averaged 235 cwt/acre and ranged from 109.5cwt/acre for Montero to 371 cwt/acre for Exacta. Exacta and XON-0101 had thehighest colossal bulb yields.

Full Season Trial, 33 Yellow VarietiesThe percentage of "bullet" single centers averaged 33.7 percent and ranged from 4percent for Delgado to 82 percent for '6011' (Table 3). Varieties 6011, Bandolero, 'SX7004 ON', and 'Sabroso' were among the highest in percentage of onions with "bullet"single centers. Varieties 6011, SX 7004 ON, Montero, Bandolero, Sabroso, 'Granero','Varsity', 'Vaquero', '4001', and 'SVR 5819' were among the highest in percentage ofonions that were functionally single centered.

Marketable yield out of storage in January 2005 ranged from 439.9 cwtlacre for Export151 to 1,025.7 cwt/acre for 'Ranchero' (Table 4). Ranchero, 'Sweet Perfection', and'OLYS97-24' were among the varieties with the highest marketable yield.Supercolossal-size onion yield ranged from 2.3 cwtlacre for Sabroso to 245.6 cwt/acrefor 6001. 6001, 'PX 2599', 'PX 5299', 'Harmony', 'Harvest Moon', and Ranchero wereamong the varieties with the highest supercolossal yield. The number of bulbs per 50lb of super colossal onions ranged from 29.8 for 'XPH95345' to 58.0 for Sabroso. Eightyellow varieties had supercolossal bulb counts above the acceptable range (averagesize too small, because almost all bulbs are at the small end of the size range) formarketing as super colossals (28-36 count per 50 Ib). None of the varieties hadsupercolossal counts below the acceptable range (averaged too big) for marketing assupercolossal. Not counting supercolossals, colossal-size onion yield ranged from 48.5cwt/acre for Export 151 to 500.8 cwt/acre for Ranchero. Ranchero, 'Torero', PX 5299,PX 2599, 0LY597-24, Harmony, and Sweet Perfection were among the highest incolossal bulb yields.

Decomposition in storage ranged from 1.5 percent for 'Daytona' to 9 percent for'Tequila'. No. 2 bulbs ranged from 5 cwt/acre for SX 70040N to 100.3 cwt/acre forHarvest Moon. Bolting averaged 0.04 bolted onions per plot and occurred in only sevenvarieties.

24

Full Season Trial, Five Red VarietiesThe percentage of "bullet" single centers averaged 25 percent and ranged from 10.8percent for 'Mercury' to 46.4 percent for 'Salsa' (Table 2). The percentage offunctionally single-centered onions averaged 44.6 percent and ranged from 24.2percent for Mercury to 64.8 percent for Salsa.

Total marketable yield ranged from 389.4 cwt/acre for 'Red Fortress' to 538.8 cwtlacrefor Mercury (Table 4). Colossal-size onion yield ranged from 19.4 cwtlacre for 'RedZeppelin' to 71.7 cwt/acre for Mercury. Decomposition in storage ranged from 1.5percent for 'Redwing' to 13.9 percent for Salsa. No. 2 bulbs ranged from 10.6 cwt/acrefor Redwing to 146.1 cwt/acre for Red Fortress.

Subjective evaluation of thrips damage to red onions in storage ranged from a rating of1.4 for Red Fortress to 3.8 for Salsa.

Full Season Trial, Five White VarietiesThe percentage of "bullet" single centers averaged 22.9 percent and ranged from 15.3percent for 'Gladstone' to 33.3 percent for 'SVR 7106' (Table 2). The percentage offunctionally single-centered onions averaged 55.7 percent and ranged from 44.7percent for 'Oro Blanco' to 76.0 percent for SVR 7106.

Total marketable yield ranged from 441.7 cwt/acre for Oro Blanco to 578.4 cwt/acre for'SVR 5646' (Table 4). Colossal-size onion yield ranged from 80.4 cwtlacre for OroBlanco to 217.5 cwt/acre for SVR 5646. Decomposition in storage ranged from 6.4percent for 'Brite Knight' to 21.6 percent for Oro Blanco. No. 2 bulbs ranged from 16.0cwt/acre for SVR 7106 to 109.6 cwt/acre for Brite Knight.

Table 1. Onion multiple-center rating and iris yellow spot virus rating for early maturingvarieties, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Functionally

Seedcompany

Sakata

Variety

XON-0101

Bulbcolor

Y

Intermediate SmallBlowout double double

0/

61.3 24.0 13.3

Bullet

1.3

single centered"bullet + small

double"

14.7

Iris yellowspot virus

rating*

0-51.84

Sakata XON-209W W 55.1 26.2 18.8 0.0 18.8 1.06Seminis Exacta Y 18.7 21.3 39.3 20.7 60.0 1.26Seminis Golden Spike Y 23.3 18.0 38.0 20.7 58.7 1.06Nunhems Renegade Y 37.3 40.0 18.0 4.7 22.7 0.68Nunhems Montero Y 0.5 4.3 18.8 76.4 95.2 1.26Average 32.7 22.3 24.4 20.6 45.0 1.19LSD (0.05)

*subjective rating: 0 = no da13.7 15.2 16.3

mage, 5 = total damage.8.3 16.0 0.55

25

Table 2. PerformanExperiment Station,

ce dataOregon

for early maturing onion varieties harvestedState University, Ontario, OR, 2004.

on August 17 and graded on Aug ust 20, Malheur

Bulbcolor

Marketable yield by grade

TotalBulb

counts

Non-marketable yield

Total SunMaturity

onCompany Entry name yield Total >41/4 in 4-4Y4 in 3-4 in in >4V4 in rot scald No. 2s Small Aug. 10 Bolters

cwtlacre --- cwtlacre #/50 lb % ---- cwt/acre ---- % #/plotSakata XON-0101 Y 912.1 818.6 37.0 344.6 420.4 16.7 30.8 0.6 34.1 44.5 8.9 53.0 0.0

XON-209W W 739.7 589.4 9.2 131.7 414.4 34.1 28.3 6.6 36.6 48.3 19.2 67.0 0.2

Seminis Exacta Y 971.4 865.6 47.2 370.9 426.6 21.0 31.8 0.7 35.1 53.0 10.5 32.0 0.2Golden Spike Y 841.5 727.3 24.7 196.4 484.3 21.9 32.6 0.8 49.2 47.1 11.1 36.0 0.0

Nunhems Renegade Y 904.9 823.5 24.2 255.7 521.2 22.5 31.9 1.7 31.6 27.0 7.5 46.0 1.2Montero Y 721.3 662.4 11.7 109.5 519.4 21.9 40.3 2.4 25.3 2.9 14.0 33.0 0.0

Average 848.5 747.8 25.6 234.8 464.4 23.0 32.6 2.1 35.3 37.1 11.9 44.5 0.3LSD (0.05) 126.0 140.0 20.2 68.7 NS NS 3.8 1.9 NS 21.5 NS 8.8 NS

N.)a)

Table 3. Onion multiple-center rating and iris yellow spot virus rating for long seasonvarieties, Malheur ExDeriment Station, Orecion State University, Ontario, OR, 2004.

Functionallysingle centered Iris yellow

Seed Bulb Intermediate Small "bullet + small spot viruscompany Variety color Blowout double double Bullet double" rating*

0-50/

A. Takii T-433 Y 24.7 47.3 20.0 8.0 28.0 0.82T-439 Y 38.0 25.3 26.7 10.0 36.7 0.889003G Y 20.0 35.3 26.7 18.0 44.7 0.88

Bejo Daytona Y 20.0 59.3 15.3 5.3 20.7 1.06Delgado Y 26.0 30.7 39.3 4.0 43.3 0.82Gladstone W 20.0 31.3 33.3 15.3 48.7 0.94Redwing R 8.0 32.0 28.0 32.0 60.0 1.06BGS 196 Fl Y 17.3 13.3 43.3 26.0 69.3 0.88

Crookham Harmony Y 18.7 37.3 3.3 40.7 44.0 1.40Sweet Perfection Y 15.3 28.0 15.3 41.3 56.7 1.00OLYS97-24 Y 21.3 29.3 24.0 25.3 49.3 1.32OLYS97-27 Y 21.3 40.0 14.7 24.0 38.7 1.26XPH95345 Y 30.0 33.3 24.0 12.7 36.7 1.32

15.3 480 18] 36.7 1.

D. Palmer Mesquite Y 22.5 46.3 15.3 16.0 31.2 1.38Tequila Y 20.0 21.3 18.7 40.0 58.7 1.12

Rispens Brite Knight W 24.7 29.3 27.3 18.7 46.0 1.18Export 151 Y 18.7 38.7 29.3 13.3 42.7 1.92Red Fortress R 30.0 29.3 20.7 20.0 40.7 1.66

Scottseed Oro Blanco W 26.0 29.3 24.7 20.0 44.7 1.20Seedworks Varsity Y 4.0 8.0 32.0 56.0 88.0 1.00

4001 Y 4.0 14.7 34.0 47.3 81.3 0.94Maverick Y 8.7 31.3 22.7 37.3 60.0 1.666011 Y 0.7 4.7 12.7 82.0 94.7 1.20

Seminis Mercury R 54.3 21.5 13.4 10.8 24.2 0.94Red Zepelin R 46.7 20.0 17.3 16.0 33.3 1.12Santa Fe Y 11.3 34.7 24.0 30.0 54.0 1.34PX 2599 Y 6.0 30.7 36.7 26.7 63.3 0.88PX5299 Y 7.3 31.3 38.7 22.7 61.3 0.82SVR 7106 W 2.0 22.0 42.7 33.3 76.0 1.26SVR 5646 W 14.7 22.0 36.0 27.3 63.3 1.12SVR 5819 Y 5.3 13.3 39.3 42.0 81.3 1.00

Nunhems Bandolero Y 3.2 3.2 12.8 80.8 93.6 0.94Grariero Y 1.3 8.7 27.3 62.7 90.0 0.94Pandero Y 9.3 26.7 26.0 38.0 64.0 1.06Ranchero Y 0.8 35.2 27.2 36.8 64.0 1.18Sabroso Y 3.2 3.2 19.2 74.4 93.6 0.88Salsa R 22.4 12.8 18.4 46.4 64.8 1.00Tesoro Y 20.0 18.0 28.7 33.3 62.0 0.94Torero Y 8.0 32.7 35.3 24.0 59.3 0.94Vaquero Y 1.3 13.3 18.0 67.3 85.3 0.94Montero Y 1.1 5.1 26.9 66.9 93.7 0.94SX7004 ON Y 2.0 3.3 15.3 79.3 94.7 1.34

Average 15.7 25.6 24.9 33.7 58.7 1.11LSD (0.05) 9.2 16.8 14.6 10.8 16.3 0.42

*subjective rating: 0 = no damage, 5 = total damage.

27

Table 4. 2004 performance data for experimental and commercial onion varieties graded out of storage in January 2005, Malheur Experiment Station, Oregon StateUniversity. Ontario. OR.

Company Entry nameBulbcolor

Totalyield

Marketa ble yield by grade Bulb

counts2Y4-3 in >41/4 in

Totalrot

Non

Neckrot

-marke

Platerot

table yield

Black No.mold 2s Small

Maturityon

Aug. 24 BoltersThrips

damage*Total >41/4 in 4-4¼ in 3-4 incwtlacre cwtlacre #/50 lb %oftotal yield cwtlacre-- % #/plot

A. Takii T-433 Y 984.2 821.3 167.9 421.7 216.4 15.3 30.4 7.6 3.2 4.1 0.3 82.3 6.7 24.0 0

T-439 Y 780.4 717.3 31.5 323.8 351.3 10.7 33.7 3.5 0.3 3.2 0.0 30.8 5.0 59.0 0

9003G Y 684.1 627.0 7.8 138.1 454.6 26.6 41.2 3.5 1.0 2.5 0.0 18.5 15.3 56.0 0

Bejo Daytona Y 680.0 624.5 8.3 139.5 444.3 32.4 38.0 1.5 0.3 1.0 0.2 32.2 12.8 43.0 0.2Delgado Y 717.4 631.5 9.2 176.9 436.4 9.1 43.4 3.0 0.8 2.2 0.0 59.7 5.8 55.0 0

Gladstone W 709.8 548.2 10.1 127.6 391.0 19.5 36.4 12.1 10.1 1.6 0.4 71.8 4.1 46.0 0.4

Redwing R 562.2 536.6 1.1 45.2 468.0 22.4 48.3 1.5 0.7 0.8 0.0 10.6 6.7 37.0 0 2.0BGS 196 Fl Y 832.3 761.8 43.1 288.1 411.6 19.1 35.5 2.6 0.3 2.3 0.0 41.6 7.5 58.0 0

Crookham Harmony Y 1040.6 902.9 221.1 447.9 223.7 10.3 30.9 5.4 3.5 1.8 0.0 77.0 5.2 37.0 0.2Sweet Perfection Y 1072.6 969.8 169.9 439.9 339.9 20.1 30.8 4.6 1.8 2.1 0.8 46.1 7.1 39.0 0

OLYS97-24 Y 1082.9 927.9 173.9 453.5 281.9 18.6 33.6 6.0 3.7 1.9 0.3 80.7 10.1 25.0 0

OLYS97-27 Y 964.9 835.6 144.7 397.9 272.7 20.1 32.1 5.7 2.6 2.6 0.5 64.4 9.8 28.0 0

XPH95345 Y 795.6 613.8 59.3 215.1 321.1 18.4 29.8 10.6 8.9 1.7 0.0 94.7 4.8 33.0 0

Dorsing Harvest Moon Y 941.2 786.2 220.8 350.6 206.2 8.7 31.5 5.7 3.4 2.1 0.2 100.3 5.3 29.0 0.2D. Palmer Mesquite Y 932.3 810.7 176.2 369.3 246.1 19.2 31.6 4.0 1.6 2.4 0.0 81.8 4.6 20.0 0

Tequila Y 1004.4 812.7 184.0 403.3 216.4 9.0 31.3 9.3 4.9 2.9 1.5 93.2 3.5 23.0 0.2

Rispens Export 151 Y 552.3 439.9 5.2 48.5 369.8 16.4 40.5 3.1 0.7 2.4 0.0 92.8 3.6 43.0 0

Brite Knight W 662.7 501.4 4.5 98.3 367.8 30.7 34.8 6.4 5.6 0.8 0.0 109.6 9.3 44.0 0

Red Fortress R 557.8 389.4 0.0 25.1 321.8 42.6 1.9 0.6 1.4 0.0 146.1 11.8 47.0 0 1.4

Scottseed Oro Blanco W 672.8 441.7 2.8 80.4 337.3 21.2 38.4 21.6 20.5 1.2 0.0 75.0 7.0 55.0 0

Global Varsity Y 655.5 616.0 30.3 195.5 378.6 11.7 35.9 3.9 0.7 3.2 0.0 10.1 5.5 68.0 0Genetics 4001 Y 683.6 638.9 10.7 140.0 464.9 23.3 42.2 3.4 0.3 3.2 0.0 15.0 7.6 69.0 0.2

Maverick Y 961.0 869.0 245.6 413.9 195.5 13.9 31.3 6.2 3.1 3.1 0.0 28.6 4.1 30.0 0

Santa Fe

Red Zepelin

PX 2599

PX 5299

SVR 7106

SVR 5646

SVR 5819

Nunhems Bandolero

Granero

Pandero

Ranchero

Sabroso

Salsa

Tesoro

Torero

Vaquero

Montero

SX7004 ON

5.9 2.4

3.3 2.0

2.5 0.8

2.4 0.8

19.9 15.2

21.1 14.6

3.6 0.9

4.3 1.7

3.2 1.5

1.7 0.2

5.7 3.2

5.4 2.0

13.9 8.5

2.5 0.7

4.1 2.3

5.3 2.5

4.2 2.2

4.6 3.1

3.6 0.0 47.0 6.0

1.3 0.0 67.3 5.5

1.7 0.0 16.1 5.4

1.6 0.1 31.8 3.8

4.7 0.1 16.0 8.1

6.1 0.4 19.5 6.4

2.7 0.0 14.7 7.1

2.5 0.1 8.0 10.6

1.6 0.1 14.8 8.8

1.5 0.0 22.0 6.2

1.7 0.8 19.1 7.3

3.4 0.0 6.8 8.7

5.4 0.0 46.0 6.4

1.8 0.0 34.5 10.5

1.6 0.1 19.1 5.5

2.8 0.0 11.9 7.4

2.0 0.0 7.8 7.7

1.6 0.0 5.0 3.1

Table 4. 2004 performance data for experimental and commercial onion varieties graded out of storage in January 2005, Malheur Experiment Station, Oregon StateUniversity. Ontario. OR.

BulbCompany Entry name color

MarketableTotalyield Total >41/4 in

yield by grade Bulb

countsin >41/4 in

Non-marketable yield Maturity

Black No. 011 Thrips

mold 2s Small Aug. 24 Bolters damage*in 3-4 in

Totalrot

Neckrot

Platerot

cwt/acre --- cwtiacre #/50 lb % of total yield cwt/acre -- % #/plot6011 Y 867.7 803.0 130.3 418.0 237.1 17.5 31.6 5.3 2.0 3.2 0.1 15.2 4.7 52.0 0

Seminis Mercury R 593.1 538.8 2.6 71.7 437.3 27.2 40.5 5.9 2.7 2.9 0.2 12.8 7.4 80.0 0 3.4

Y 904.6 798.4 171.1 374.8 240.8 11.7

R 518.1 428.2 2.7 19.4 373.8 32.2

Y 945.8 900.7 244.2 464.7 182.3 9.4

Y 954.3 895.5 227.9 467.3 193.8 6.4

W 660.8 504.9 8.9 136.7 343.4 15.9

W 767.1 578.4 19.3 217.5 331.1 10.5

Y 950.3 895.3 130.0 440.9 309.5 15.0

Y 674.7 626.9 3.7 52.2 536.4 34.6

Y 913.1 861.1 71.8 429.1 339.4 20.8

Y 928.8 884.5 132.7 428.6 310.6 12.6

Y 1115.0 1025.7 205.8 500.8 302.6 16.5

Y 620.5 571.7 2.3 69.6 478.6 21.2

R 529.7 404.9 0.0 62.4 320.1 22.3

Y 749.3 686.3 7.8 202.1 457.8 18.6

Y 952.4 889.2 170.5 483.3 223.5 11.9

Y 930.1 861.6 65.6 403.4 373.4 19.2

Y 848.1 798.9 45.2 337.3 398.2 18.2

Y 904.1 856.7 68.3 424.0 356.5 7.8

30.3

56.9

31.5

30.9

34.4

37.2

31.8

45.5

34.3

32.3

30.7

58.0

39.7

32.2

34.2

35.7

32.7

29.0

78.0

21.0

33.0

63.0

58.0

31.0

73.0

35.0

23.0

49.0

58.0

70.0

59.0

40.0

46.0

75.0

50.0

0

0 2.6

0

0

0

0

0

0

0

0.2

0

0

0 3.8

0.2

0

0

0

0

* Thrips damage: 0 = least damage, 10 = most damage.

Average 810.6 712.4 84.6 273.1 336.4 18.3 36.1 6.0 3.4 2.4 0.1 44.1 7.0 46.3 0.04 2.6

LSD(0.05) 86.0 101.2 46.1 68.9 81.1 16.2 5.5 5.6 '4.3 2.2 NS 23.0 NS 8.0 NS 1.2

PUNGENCY OF SELECTED ONION VARIETIES BEFORE AND AFTER STORAGE

Clinton C. Shock, Erik B. G. Feibert, and Lamont D. SaundersMalheur Experiment Station


Introduction

The objective of this trial was to evaluate the pungency of 12 onion varieties commonlygrown in the Treasure Valley.

Methods

Varieties for pungency analysis were selected based on information provided by theseed companies on their probability of being mild (Tables 1 and 2). 'Vaquero' wasincluded as the industry standard variety of the Treasure Valley.

The onions were grown on a Owyhee silt loam previously planted to wheat. Onion seedwas planted on March 19, 2004. The procedures for growing the onions can be foundin the "2004 Onion Variety Trials" report by Shock et al. in this report. Onions in theearly maturity trial were lifted on August 13, topped by hand and bagged on August 17,and graded on August 20. The onions in the full-season trial were lifted on September8 to field cure. Onions in the full season trial were topped by hand and bagged onSeptember 15. The bags were put in storage on September 22. The storage shed wasmanaged to maintain an air temperature of approximately 34°F. Onions from the fullseason trial were graded out of storage in early January 2005.

On August 25, 10 bulbs from each of 5 plots of each of 3 varieties of the early maturingtrial were sent to Vidalia Labs International (Collins, GA), by UPS ground, for pyruvateand sugars analysis. On October 5, 10 bulbs from each of 5 plots of each of 9 varietiesof the full season trial were sent to Vidalia Labs International for pyruvate analysis.After storage, a second sample of 10 bulbs from each plot of the 9 full season varietieswas sent to Vidalia Labs on January 14, 2005.

Bulb pyruvic acid content is related to onion pungency, with the units of measurementbeing micromoles pyruvic acid per gram of fresh weight (pmoles/g FVV). Onions withlow pungency can taste sweet, because the sugar can be tasted. Onion bulbs having apyruvate concentration of 5.5 or less are considered "sweet" according to Vidalia Labssweet onion certification specifications. Sugars were analyzed by the Brix method.

30

Results

None of the early maturing varieties evaluated for pyruvate in 2004 had concentrationslow enough to be considered sweet (Table 1). Of these, 'Renegade' was among thevarieties with the lowest pyruvate concentration. 'Exacta' had the lowest sugar content.In 2003, variety Renegade, grown from transplants and harvested in July, had anaverage pyruvate concentration of 5.5 pmoles/g FW (Shock et al. 2004a).

On October 15, 2004 and January 24, 2005, none of the full season varieties hadpyruvate concentrations low enough to be considered sweet (Table 2). There was nosignificant difference in either pyruvate concentration or sugar content betweensampling dates. Varieties 'Harmony' and 'PX 5299' were among the varieties with thelowest pyruvate concentration. Varieties 'SVR 5819' and Vaquero were among thevarieties with the highest sugar content. In 2003, the average pyruvate concentration ofselected full season varieties was 5.3 pmoles/g FW in October and 7.9 pmoles/g FW inJanuary, 2004 (Shock et al. 2004b).

References

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2004a. Onion production fromtransplants in the Treasure Valley. Oregon State University Agricultural ExperimentStation Special Report 1055:47-52.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2004b. Pungency of selected onionvarieties before and after storage. Oregon State University Agricultural ExperimentStation Special Report 1055:45-46.

Table 1. Pyruvate concentration and estimated sugar concentration of selected earlymaturing onion varieties on September 2, 2004, Malheur Experiment Station, Ontario,OR.Seedcompany Variety

Pyruvateconcentration Sugarspmoles/g FW % Brix

Seminis ExactaGolden Spike

6.366.84

8.889.92

Nunhems Renegade 5.83 9.75AverageLSD (0.05)

6.340.60

9.520.60

31

Table 2. Pyruvate conseason onion varieties

centration and estimated suin 2003 and 2004, Malheur

gar concentration of selected fullExperiment Station, Ontario, OR.

Date Company Variety

2003 2004

Pyruvate Sugars Pyruvate Sugarsconcentration concentrationpmoles/g FW % Brix pmoles/g FW % Brix

October A. Takii T-439 4.66 8.08 8.38 - 8.44 -Crookham Harmony 6.08 8.88 7.24 - - - 8.80 - -Seedworks 6011 4.90 9.04 8.04 8.64

Seminis Santa Fe

PX 5299

SVR 5819

5.66

-8.80 8.62 8.64

6.63 8.25

9.88 9.48

Nunhems RancheroVaquero

SX7002 ON

5.60

5.62

4.70

8.56 8.80 8.04

9.00 9.10 9.00

8.56 7.52 8.16Average 5.32 8.70 8.25 8.61

January A. Takii T-439 7.54 7.56 8.50 8.48

Crookham Harmony 6.40 8.72 6.60 8.56

Seedworks 6011 8.12 8.56 8.02 8.64Seminis Santa Fe

PX 5299

SVR 5819

8.22 8.28 7.96 9.00

8.33 8.40

8.84 9.04

Nunhems Ranchero

Vaquero

SX7002 ON

8.34

8.90

7.84

8.12 8.34 8.24

8.64 8.92 8.80

7.48 8.40 8.12Average 7.91 8.19 8.21 8.59

Average A. Takii T-439 6.10 7.82 8.44 8.46Crookham Harmony 6.24 8.80 6.92 8.68Seedworks 6011 6.51 8.80 8.03 8.64Seminis Santa Fe

PX 5299

SVR 5819

6.94 8.54 8.29 8.82

7.48 8.32

9.36 9.26

Nunhems RancheroVaquero

SX7002 ON

6.97

7.26

6.27

8.34 8.57 8.14

8.82 9.01 8.908.02 7.96 8.14

Average 6.61 8.45 8.23 8.60LSD (0.05) Date 0.08 0.17 NS NSLSD (0.05) Variety 0.56 0.35 0.71 0.43LSD (0.05) Date X variety 0.79 NS 1.00 NS

32

EFFECT OF SHORT-DURATION WATER STRESS ON ONION SINGLECENTEREDNESS AND TRANSLUCENT SCALE

Clinton C. Shock, Erik Feibert, and Lamont SaundersMalheur Experiment Station


Introduction

In earlier trials we have shown that onion yield and grade are very responsive to carefulirrigation scheduling and maintenance of soil moisture (Shock et at. 1 998b, 2000).Using a high-frequency automated drip-irrigation system, the soil water potential at8-inch depth that resulted in maximum onion yield, grade, and quality after storage wasdetermined to be no drier than -20 kPa. It is not known whether short-term waterstress, caused by irrigation errors, could result in internal bulb defects such as multiplecenters and translucent scale. This trial tested the effects of short-duration water stressat different times during the season on onion single centeredness and translucentscale.


The onions were grown at the Malheur Experiment Station, Ontario, Oregon on anOwyhee silt loam previously planted to wheat. Soil analysis indicated the need for 60 lbNitrogen (N)/acre, 100 lb phosphorus/acre, 100 lb Potassium/acre, 70 lb sulfur/acre, 2lb copper/acre, and 1 lb boron/acre, which was broadcast in the fall. Onion (cv.'Vaquero', Nunhems, Parma, ID) was planted in 2 double rows, spaced 22 inches apart(center of double row to center of double row) on 44-inch beds on March 17, 2004. The2 rows in the double row were spaced 3 inches apart. Onion was planted at 150,000seeds/acre. Drip tape (T-tape, T-systems International, San Diego, CA) was laid at4-inch depth between the 2 double onion rows at the same time as planting. Thedistance between the tape and the double row was 11 inches. The drip tape hademitters spaced 12 inches apart and a flow rate of 0.22 gal/min/100 ft.

Immediately after planting the onion rows received 3.7 oz of Lorsban 1 5G® per 1,000 ftof row (0.82 lb ai/acre), and the soil surface was rolled. Onion emergence started onApril 2. The trial was irrigated on April 5 with a minisprinkler system (RIO TurboRotator, Nelson Irrigation Corp., Walla Walla, WA) for even stand establishment.Risers were spaced 25 ft apart along the flexible polyethylene hose laterals that werespaced 30 ft apart, and the water application rate was 0.10 inch/hour.

The experimental design was a randomized complete block with five replicates. Therewere six drip-irrigated treatments that consisted of five timings of short-duration waterstress and an unstressed check. Each plot was 4 rows by 50 ft. Each plot had a ball

33

valve allowing manual control of irrigations. The water stress was applied by turning thewater off manually to all plots in a treatment until the average soil water potential at8-inch depth for the treatment reached -60 kPa; at this point, the water to all plots inthat treatment was turned on again. Each treatment was stressed once during theseason. The four timings for the stress treatments were: two-leaf stage (water off May5, water back on June 2), four-leaf stage (water off May 25, water back on June 4),early six-leaf stage (water off June 2, water back on June 11), late six-leaf stage (wateroff June 11, water back on June 16), and eight-leaf stage (water off June 18, waterback on June 24).

Soil water potential (SWP) was measured in each plot with four granular matrix sensors(GMS, Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside,CA) installed at 8-inch depth in the center of the double row. Sensors were calibratedto SWP (Shock et al. 1 998a). The GMS were connected to the datalogger with threemultiplexers (AM 410 multiplexer, Campbell Scientific, Logan, UT). The dataloggerread the sensors and recorded the SWP every hour. The irrigations were controlled bythe datalogger using a relay driver (A21 REL, Campbell Scientific, Logan, UT)connected to a solenoid valve. Irrigation decisions were made every 12 hours by thedatalogger: if the average SWP at 8-inch depth in the unstressed treatment plots was-20 kPa or less the field was irrigated for 4 hours. The pressure in the drip lines wasmaintained at 10 psi by a pressure regulator. Irrigations were terminated on September2.

Onion tissue was sampled for nutrient content on June 13. The roots from four onionplants in each check plot were washed with deionized water and analyzed for nutrientcontent by Western Labs, Parma, ID. The onions in all treatments were fertilizedaccording to the plant nutrient analyses. Urea ammonium nitrate solution at 50 lbN/acre was applied through the drip tape on May 27 and on June 17.

Prior to onion emergence, Roundup® at 24 oz/acre was sprayed on March 29. The fieldhad Prowl®(llb ai/acre) broadcast on April 12 for postemergence weed control.Approximately 0.45 inch of water was applied through the minisprinkler system on April12 to incorporate the Prowl. The field had Goal® at 0.12 lb al/acre, Buctril® at 0.12 lbai/acre, and Poast® at 0.28 lb ai/acre applied on May 25. Thrips were controlled withone aerial application of Warrior® on June 12, one aerial application of Warrior (0.03 lbai/acre) plus Lannate® (0.4 lb al/acre) on June 25, one aerial application of Warrior(0.03 lb al/acre) plus MSR®(0.5 lb al/acre) on July 17, and one aerial application ofWarrior (0.03 lb ai/acre) plus Lannate (0.4 lb al/acre) on July 31.

On September 9 the onions were lifted to cure. On September 15, onions in the central40 ft of the middle 2 double rows in each plot were topped and bagged. The bags wereplaced into storage on September 29. The storage shed was managed to maintain anair temperature of approximately 34°F. The onions were graded on December 9.Bulbs were separated according to quality: bulbs without blemishes (No. Is), doublebulbs (No. 2s), neck rot (bulbs infected with the fungus Botiytis al/li in the neck or side),plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold (bulbs

34

infected with the fungus Aspergillus niger). The No. I bulbs were graded according todiameter: small (<2.25 inch), medium (2.25-3 inches), jumbo (3-4 inches), colossal(4-4.25 inches), and supercolossal (>4.25 inches). Bulb counts per 50 lb ofsupercolossal onions were determined for each plot of every variety by weighing andcounting all supercolossal bulbs during grading.

After grading, 50 bulbs ranging in diameter from 3.5 to 4.25 inches from each plot wererated for single centers and translucent scale. The onions were cut equatorially throughthe bulb middle and, if multiple centered, the long axis of the inside diameter of the firstsingle ring was measured. These multiple-centered onions were ranked according tothe diameter of the first single ring: "small doubles" have diameters less than 1 .5 inch,"intermediate doubles" have diameters from 1 .5 to 2.25 inches, and "blowouts" havediameters greater than 2.25 inches. Single-centered onions are classed as a "bullet".Onions are considered functionally single centered for processing if they are a "bullet"or "small double." The number and location of translucent scales in each bulb was alsorecorded.


The SWP at 8-inch depth during the stress treatments reached values lower than theplanned -60 kPa (Fig. 1). Irrigations for the plots being stressed were restarted as soonas the SWP reached -60 kPa. In addition to being difficult to catch the SWP when itfirst reaches -60 kPa, the drip tape was located 11 inches from the soil moisturesensors, which caused a short delay between the onset of irrigations and when thewetting front reached the sensors, so that they would begin responding to theirrigations.

At no stage did water stress affect onion single centeredness or the incidence of bulbswith translucent scale in 2004 (Table 1). Single-centered "bullet" and functionallysingle-centered bulbs averaged 80.5 and 93.8 percent, respectively. Bulbs withtranslucent scale averaged 1.1 percent. In 2003, water stress at the four-leaf andsix-leaf stages resulted in significantly lower single-centered and functionallysingle-centered bulbs than the unstressed check (Shock et al. 2004). In 2004 therewere relatively few other sources of stress than those imposed by the trial treatments,suggesting a possible role of multiple sources of stress influencing multiple-centeredbulbs.

The short-duration water stress in this trial did not affect onion yield or grade. Theaverage onion yields in this trial were: 1,016.4 cwt/acre total yield, 980.5 cwt/acremarketable yield, 7.0 cwtlacre supercolossal yield, 164.3 cwt/acre colossal yield, and786.4 cwt/acre jumbo yield. In contrast, in a previous study by Hegde (1986), onionyield and size were reduced by short-duration water stress to -85 kPa, with the onionsotherwise irrigated at -45 kPa. In that study, the SWP at which the onions wereirrigated was drier (-45 kPa) than in our study (-20 kPa) and the irrigation frequency wasmuch lower, possibly causing the difference in results.

35

References

Hegde, D.M. 1986. Effect of irrigation regimes on dry matter production, yield, nutrientuptake and water use of onion. Indian J. Agronomy 31:343-348.

Shock, C.C., J.M. Barnum, and M. Seddigh. 1998a. Calibration of Watermark SoilMoisture Sensors for irrigation management. Pages 139-146 in Proceedings of theInternational Irrigation Show, Irrigation Association, San Diego, CA.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 1998b. Onion yield and qualityaffected by soil water potential as irrigation threshold. HortScience 33:188-191.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2000. Irrigation criteria fordrip-irrigated onions. HortScience 35:63-66.

Shock, C.C., E. Feibert, and L. Saunders. 2004. Effect of short duration water stress ononion single centeredness and translucent scale. Oregon State University AgriculturalExperiment Station Special Report 1055:53-56.

Table 1. Onion multiple-center rating and translucent scale response to timing of waterstress, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Functionallysingle

centered

Water stress timingIntermediate Small

Blowout* doublet doubletBullet + small Translucent

Bullets double scale%

Check, no stress 1.6 4.8 12.0 81.6 93.6 2.02-leaf stage, early May 2.0 2.8 11.2 84.0 95.2 0.04-leaf stage, late May 2.4 5.2 11.2 81.2 92.4 2.46-leaf stage, early June 2.4 4.0 14.4 79.2 93.6 0.86-leaf stage, mid-June 2.0 4.1 15.5 78.3 93.8 1.68-leaf stage, late June 1.6 4.4 15.2 78.8 94.0 0.0LSD (0.05) NS NS NS NS NS NS*Blowout: diameter of the first single ring >21/4 inches.intermediate double: diameter of the first single ring 1 %-21h inches.tSmall double: diameter of the first single ring <1 1/2 inch.

single-centered.

36

0

-20

-40

-60

-800

-20

-40

-60

0

0

-20

-40

-60

-80

0

-20

-60

-80126 224 248

Day of year

Figure 1. Soil water potential for onions irrigated at -20 kPa with an automateddrip-irrigation system and submitted to short-duration water stress, Maiheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

37

check, no stress

mid June stress

late June stress

150 175 199

TREATMENT OF ONION BULBS WITH SURROUND® TOREDUCE TEMPERATURE AND BULB SUNSCALD

Clinton C. Shock, Erik B. G. Feibert, and Lamont D. SaundersMalheur Experiment Station


Introduction

Onion prices generally decrease starting in September when harvest intensifies.Harvesting earlier from overwintered, transplanted, or normally planted full seasononions could increase profits, but mechanized early harvest runs the risk of increasedlosses to sunscald. Sunscald occurs when the side of the bulb exposed to afternoonsun becomes excessively hot. Sunscald results in a flattened and shrunken area onthe bulb surface. The 59-year-average maximum air temperature at the MalheurExperiment Station is 91, 90, and 80°F for July, August, and September, respectively.Maximum air temperatures in July and August often exceed 100°F, which can result invery high unprotected bulb temperatures and sunscald. Surround® (Engelhard Corp.,Iselin, NJ) is a product made from kaolinite clay and works by forming a white coatingon surfaces, thus reflecting solar radiation. Surround is a wettable powder that islabeled for reduction of sunscald in fruits and vegetables. Application of Surround afteronions are lifted could reduce sunscald and make early mechanized harvests morefeasible.

Methods

Trials were conducted in two fields in 2004.

Procedures for Growing Onions in Field IThe onions were grown with subsurface drip irrigation at the Malheur ExperimentStation, Ontario, Oregon on an Owyhee silt loam previously planted to wheat. Onion(cv. 'Vaquero', Nunhems, Parma, ID) was planted on March 17, 2004. The procedurescan be found in "Effect of Short-duration Water Stress on Onion Single Centerednessand Translucent Scale" by Shock et al. in this report.

Procedures for Growing Onions in Field 2The onions were grown with furrow irrigation on an Owyhee silt loam previously plantedto wheat. Onion seed ('Vaquero') was planted on March 19, 2004. The procedurescan be found in "2004 Onion Variety Trials" by Shock et al. in this report.

Procedures for Surround TreatmentsOnions in each field were lifted on August 9. The lifted onions were divided into plots23 ft long. The experimental designs were randomized complete blocks with four

38

replicates in each field. There were seven treatments: treatment 1 was untreated; 2received one Surround application after lifting; 3 received one Surround applicationafter lifting and one after windrowing; and 4 was treated after windrowing (Table 1).Treatments 2-4 had an application rate of 25 lb Surround/acre. Treatments 5-7 werethe same as treatments 2-4, except that the application rate was 50 lb Surround/acre.The Surround was applied after lifting on August 9 with a ground sprayer and a boomwith 9 nozzles spaced 10 inches apart. The Surround was applied in 102 galwater/acre with 8004 nozzles at 40 psi.

Prior to the Surround application, temperature probes were installed in bulbs at 0.5-cmdepth. The temperature probes in the monitored bulbs were placed so that they facedto the south-southeast in a position receiving direct sun. Three replicates in thedrip-irrigated field and two replicates in the furrow-irrigated field each had one bulbmonitored for temperature. The temperature probes were read hourly by a datalogger(Hobo datalogger, Onset Computer Corp., Bourne, MA).

On August 12 the temperature probes and probed onions were removed and the onionswere topped and wind rowed by hand. After wind rowing the temperature probes werereinserted in different onions as before. The onion wind row was sprayed with Surroundusing a ground sprayer with 3 nozzles spaced 10 inches apart. Application rates andspecifications were the same as the initial Surround application. Since only thewindrow was sprayed (one-third of the field), the application rates were reduced to 8.3lb Surround/acre for treatments 2-4 and to 17 lb Surround/acre for treatments 5-7.

The onions were bagged on August 16 and hauled to a shed. On August 19 the onionswere graded. Bulbs were separated according to quality: bulbs without blemishes (No.is), bulbs with sunscald damage, double bulbs (No. 2s), neck rot (bulbs infected withthe fungus Bottytis al/il in the neck or side), plate rot (bulbs infected with the fungusFusarium oxysporum), and black mold (bulbs infected with the fungus Aspergi//usniger). The No. 1 bulbs were graded according to diameter: small (<2.25 inches),medium (2.25-3 inches), jumbo (3-4 inches), colossal (4-4.25 inches), andsupercolossal (>4.25 inches). Bulb counts per 50 lb of supercolossal onions weredetermined for each plot by weighing and counting all supercolossal bulbs duringgrading.

To reduce the influence on the statistical analysis of the variability in onion yield andsize between plots, the data for each field were normalized in relation to the averagetotal yield for that field. Normalized data were subjected to analysis of variance.


The highest air temperature reached after lifting of the onions and before topping andwindrowing was 100°F on August 11 (Table 2). The highest average bulb temperaturereached after onions were lifted and before they were topped and windrowed was129.5°F. Following the application of Surround after lifting on August 9, averagemaximum bulb temperatures were reduced 6-7°F compared to the untreated bulbs, but

39

the temperature differences were statistically significant only on August 9 (Table 2, Fig.1). Bulb temperatures for the 50-lb/acre Surround rate were slightly lower than for the25 lb/acre rate, but the differences were not statistically significant.

The highest air temperature reached after topping and windrowing on August 12 was99°F on August 13 (Table 3). The highest average bulb temperature reached aftertopping and windrowing was 129.2°F. For the onions treated with Surround aftertopping and windrowing, average maximum bulb temperatures were reduced by 5-6°Fcompared to the untreated check (Table 3, Fig. 1). After topping and windrowing, thebulb temperature differences between treatments were statistically significant for alldays measured (August 12-15). After topping and windrowing, bulb temperatures forthe 50-lb/acre Surround rate were slightly lower than for the 25-lb/acre rate and thedifferences were statistically significant on August 13, August 15, and on average.

The furrow-irrigated field (field 2) had lower marketable yield and higher yield of onionswith sunscald than the drip-irrigated field (field 1, Table 4). There were no significantdifferences in onion yield or grade between treatments. However, in Field 2 there wasa small but significant reduction in rot with increasing total amount of Surround applied(Fig. 2). In 2003, application of Surround resulted in statistically significant reductions inbulb sunscald and in increases in marketable yield (Shock et al. 2004). In 2003, thehighest bulb temperature reached after lifting was 123°F and the highest bulbtemperature after topping and windrowing was 121°F. These bulb temperatures were6.5 and 8.2°F lower than the highest bulb temperatures in 2004. The higher bulbtemperatures in 2004 could be related to the higher average bulb sunscald in 2004 (152cwt/acre) compared to the average sunscald in 2003 (37 cwt/acre). The higher bulbtemperatures in 2004 might also be related to the higher air temperatures reachedduring the 2004 trial (average of 97°F) than during the 2003 trial (average of 94°F).

References

Shock, CC., E.B.G. Feibert, and L.D. Saunders. 2004. Treatment of onion bulbs with"Surround" to reduce temperature and bulb sunscald. Malheur Experiment StationAnnual Report, Oregon State University Agricultural Experiment Station Special Report1055:75-79.

40

Table 1.Maiheur

Treatments applied to onionExperiment Station, Oregon

s to evaluate two application rates of Surround®,State University, Ontario, OR, 2003.

Treatment Surround Post lifting Post topping andrate Surround windrowing Surround

lb/acre application application1 none No No2 25 Yes No3 25 Yes Yes4 25 No Yes5 50 Yes No6 50 Yes Yes7 50 No Yes

Table 2. Maximum daily air temperature and maximum bulb temperature (°F) at 0.5-cmdepth for onions treated with two rates of Surround® after lifting, Malheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

Date Maximum air Solar radiationtemperature

Surround rate lb/acre LSDnone 25 50 (0.05)

°F 24-hr total watt hr/m2 °F9Aug 92 7,531 123.6 116.2 114.2 5.410 Aug 97 7,340 127.4 122.6 120.7 NS11 Aug 100 7,204 129.5 124.2 123.7 NS

Average 126.8 121.0 119.5 NS

Table 3. Maximum daily air temperature, solar radiation, and maximum bulb tempera-ture (°F) at 0.5-cm depth for onions treated with two rates of Surround® after toppingand windrowing, Malheur Experiment Station, Oregon State University, Ontario, OR,2004

Date Maximum airtemperature

Solar radiation Surround rate lb/acre LSDnone 25 50 (0.05)

°F 24-hr total watt hr/m212 Aug 98 7,081 128.4 123.0 121.5 3.4l3Aug 99 6,830 126.5 121.2 119.7 1.4l4Aug 97 4,769 125.8 120.5 119.5 1.515 Aug 96 6,656 129.2 125.5 123.6 1.4

Average 127.5 122.5 121.1 1.2

41

U-0

U)

C',

U)

EU)

-Q

130

120U)

C',L.U)

EU)

70

50

U-0

U)

C',

U)

FU)

-Q

Check - no Surround

130

120

110

100

908070

60

50

Surround at 25 lb/acre

A A

Surround at 50 tb/acre

130

120

110

100 -

90

80

7060

50221 222 223 224 225 226 227 228

Day of year

Figure 1. Onion bulb temperature over time for untreated bulbs and bulbs treated withtwo rates of Surround, Maiheur Experiment Station, Oregon State University, Ontario,OR, 2004.

42

Table 4. Onion yield and grade response to application of two rates of Surround® in adrip-irrigated field (field 1) and in a furrow-irrigated field (field 2), Malheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

—Surround

rate 1st applic. 2nd applic. ble yield

Non-marketable yield

Marketa Small Doubles Scald Rot

lb/acre cwt/acre % of total cwt/acreField 1

none No No 674.0 79.2 7.9 0.4 165.3 3.025 Yes No 697.8 82.0 8.1 2.8 140.2 1.6

25 Yes Yes 718.7 84.5 6.7 0.8 121.8 2.625 No Yes 703.5 82.7 8.8 1.7 132.5 4.250 Yes No 667.2 78.4 9.4 0.0 172.2 1.8

50 Yes Yes 712.7 83.8 8.0 0.4 126.2 3.250 No Yes 712.9 83.8 9.5 0.6 125.2 2.4

average 698.1 82.1 8.3 1.0 140.5 2.7Field 2

none No No 641.3 76.4 3.8 0.7 189.1 4.625 Yes No 664.7 79.2 4.4 0.7 168.6 1.225 Yes Yes 672.5 80.1 5.1 0.8 159.1 2.1

25 No Yes 676.0 80.5 3.8 2.2 155.5 2.150 Yes No 673.3 80.2 2.7 1.5 161.1 1.1

50 Yes Yes 679.9 81.0 4.6 2.3 150.9 1.850 No Yes 651.5 77.6 3.2 3.0 179.7 2.2

average 665.6 79.3 3.9 1.6 166.3 2.1

Fields 1 and 2 averagenone No No 657.7 77.8 5.9 0.6 177.2 3.825 Yes No 681.3 80.6 6.2 1.8 154.4 1.425 Yes Yes 695.6 82.3 5.9 0.8 140.4 2.325 No Yes 689.7 81.6 6.3 1.9 144.0 3.150 Yes No 670.2 79.3 6.0 0.7 166.7 1.450 Yes Yes 696.3 82.4 6.3 1.4 138.6 2.550 No Yes 682.2 80.7 6.4 1.8 152.4 2.3LSD (0.05) Trt NS NS NS NS NS NS NS

LSD (0.05) Field NS NS 2.7 NS NS 22.6 NSLSD (0.05) Trt X Fid NS NS NS NS NS NS NS

43

0C',

0C/)

0

000

I

.

20 40 60 80

8

7.• Y = 5.13- 0.115X + 0.000713X2

6 • R2 = 0.50, P = 0.001

5

_

4

3

2

1-0 --

0 100

Surround rate, lb/acre

Figure 2. Effect of total amount of Surround® applied on onion decomposition in afurrow-irrigated field, Malheur Experiment Station, Oregon State University, Ontario,OR, 2004.

44

EFFECT OF ONION BULB TEMPERATURE AND HANDLING ON BRUISING

Clinton C. Shock and Erik FeibertMalheur Experiment Station


Introduction

There is some evidence that onion handling after harvest can bruise bulbs and causesymptoms similar in appearance to translucent scale. Several shippers have suggestedthat the effect of handling on bruise may be influenced by bulb temperature duringhandling and by length of time after handling before the onions are checked. This trialtested the effect of handling 4 onion varieties at 2 temperatures on bruise and on bulbrecovery after 3 days storage at 38°F.

Methods

Trial IPrior to evaluating variety susceptibility to bruise in January 2004, a preliminary test ofthe effect of drop height on bruise was conducted. Fifteen onions from mixed varietieswere each dropped on their sides onto a concrete floor from heights of 0.8 m (2 ft, 7inches), 1 m (3 ft, 4 inches), 1.2 m (3 ft, 11 inches), or 1.4 m (4 ft, 7 inches). Theonions were cut equatorially and rated for damage. During rating we noted where in thebulb the damage occurred and whether the appearance was of translucent or watery,mushy rings. The damaged or bruised area had the form of a triangle (Fig. 1) whichextended from the surface to the center of the bulb. When the affected scales weretranslucent, the damage was different from typical translucent scale in that the scaleswere only translucent in the bruised area.

bruised area width of damage

Figure 1. Diagram of onion bulb damage or bruising resulting from a drop of I m (3 ft, 4inches).

45

N

All drop heights resulted in bulb damage (Table 1). The lowest drop height of 0.8 m (2ft, 7 inches) resulted in less pronounced damage.

Tablebeing

1. Number of onions out of 15 with visible damage or translucent scaledropped on a concrete floor from different heights.

Drop heightOnions with damagemeters (ft, inches)

0.0 0 Oofl50.8 2'7" 10*ofl510 3'4" 8of151 2 3'll" 10 of 151.4 4'7" llofl5

*damage was less pronounced.

Trial 2Onions of four varieties were randomly placed in nylon mesh bags (24 bags pervariety). Given the availability of bulbs, there were 24 bulbs/bag of 'Delgado' (BejoSeeds), 28 bulbs/bag of 'Granero', 27 bulbs/bag of 'Vaquero', and 30 bulbs/bag of'Bandolero' (all three Nunhems). On January 13, 2005 the 24 bags of each varietywere placed in 2 coolers: 12 at 32°F and 12 at 38°F. Three days later the bags wereremoved a few at a time from the coolers and were either not handled or handled bydropping each bulb from each bag individually on its side onto a concrete floor from aheight of I m (3 ft, 4 inches). The spot of impact was marked on the onion bulb. Afterthe handling treatments, half of the bags were put in a cooler at 38°F and the bulbs inthe other half of the bags were immediately cut equatorially and rated for bruising.Three days after dropping, the onions in the bags stored in the cooler were ratedindividually for bruising. The number of bruised bulbs and the number of bruised ringsin bruised bulbs was recorded. The width of the bruised area (Fig. 1) was alsorecorded. Rings with a watery appearance were judged to be bruised. Each treatmentwas replicated three times (three bags) for each variety (Table 2).

Table 2. Treatments applied to four onion varieties in January 2005.Treatment Pretreatment

storageHandlingtreatment

Post-treatmentstorage

1 32°F Drop no storage2

3storage at 38°F

No Drop no storage4 storage at 38°F5 38°F Drop no storage6

7storage at 38°F

No Drop no storage8 storage at 38°F

46

Results

Averaged over varieties and pretreatment storage temperatures, 82.2 percent of thedropped bulbs showed bruise damage compared to 1.6 percent of the bulbs that werenot dropped (Table 3). There was no significant difference in the percentage of bruisedbulbs before or after storage. In 2004, the percentage of bruised bulbs was higher afterstorage, because the affected rings became more translucent and hence moredetectable. In 2005, the damage before storage, in the form of mushy, watery rings,was easy to detect. Averaged over varieties, the percentage of dropped bulbs thatshowed bruise damage after storage was similar in 2004 (80.4) and in 2005 (81.6).

Averaged over varieties, there was no significant difference in percentage of bruisedbulbs that were at 32°F (81 percent) when dropped compared to bulbs that were at38°F (83.2 percent). In 2004, there was a small but significant difference between thepercentage of bruised bulbs that were at 32°F (75.6 percent) when dropped and bulbsthat were at 38°F (70.8 percent). Averaged over varieties, the percentage of rings thatshowed bruising in bruised bulbs was higher in bulbs stored at 38°F (69.9 percent) thanat 32°F (64.9 percent). In 2004, the percentage of rings that showed bruising inbruised bulbs was higher in bulbs stored at 32°F (91 .8 percent) than at 38°F (89.4percent).

Averaged over temperature, variety, and handling treatment, the percentage of ringsthat showed bruising in bruised bulbs was lower after 3 days of storage (53.1 percent)than immediately after dropping (81.6 percent). In 2004, averaged over temperatureand variety, the percentage of rings that showed bruising in bruised bulbs was alsolower after 3 days of storage (82.4 percent) than immediately after dropping (98.8percent), but the difference was smaller than in 2005. Averaged over temperature andvariety, the width of the bruised area was narrower after 3 days of storage thanimmediately after dropping.

There was no significant difference between varieties in the percentage of bruisedbulbs. Averaged over temperature and time, Granero had the highest percentage ofbruised rings in bruised bulbs, and Vaquero had among the lowest percentage ofbruised rings. The width of damage in bruised bulbs was widest for Granero. Granerowas the only variety that did not have a lower percentage of rings that showed bruisingin bruised bulbs after storage. In 2004, Vaquero had the highest percentage of bruisedbulbs and Bandolero was among the lowest in percentage of bruised bulbs. In 2004,Bandolero and Vaquero were among the lowest in percentage of bruised rings inbruised bulbs.

Discussion

Onions are clearly very sensitive to bruise injury during handling, which could contributeto undesirable bulb quality at arrival for retail sales and processing. The influence ofbulb temperature at dropping on bruising was small in 2004 and 2005. Bruisingdamage can become more evident over time after dropping, as in 2004. However, bothin 2004 and 2005 a healing process started, as shown by the lower percentage of

47

bruised rings in bruised bulbs after 3 days of storage. It would be desirable to explorethe recovery time necessary for bruising injury to disappear.

There were differences between the varieties in susceptibility to bruising injury, but thedifferences were small and not consistent between years. The full range of variability invariety susceptibility to bruising injury is not known. Observations were made only onfour varieties in this preliminary trial.

48

Table 3. Effect of prehandling temperature, handling, and time after handling on onionbulb bruising, Malheur Experiment Station, Oregon State University, Ontario, OR, 2005.

Variety

Prehandlingstorage Handlingtemperature treatment

Bruised bulbsAffected rings in

bruised bulbsWidth of damage in

bruised bulbs

Before Afterstorage storage

Avg. Before After Avg.storage storage

Before After Avg.storage storage

°F 0/ 0/ cmDelgado

Granero

32 Drop

No Drop38 Drop

No Drop

Avg Drop

No Drop

32 Drop

No Drop

38 Drop

No Drop

Avg Drop

No Drop

91.7 87.5

4.2 0.0

76.4 90.3

0.0 0.0

84.0 88.9

0.0 0.0

85.7 65.5

1.2 3.6

81.0 97.6

6.0 1.2

83.3 81.5

3.6 2.4

89.6

2.1

83.3

0.0

86.5

0.0

75.6

2.4

89.3

3.6

82.4

3.0

92.1 51.9 72.0

18.2 0.0 9.1

84.8 58.1 71.5

0.0 0.0 0.0

88.4 55.0 71.7

0.0 0.0 0.0

83.6 51.3 67.5

25.0 17.9 21.4

80.4 78.8 79.6

41.7 19.4 30.6

82.0 65.1 73.5

33.4 18.7 26.1

5.4 4.8 5.1

1.4 0.0 0.7

5.8 5.0 5.4

0.0 0.0 0.0

5.6 4.9 5.3

0.0 0.0 0.0

5.9 3.9 4.9

1.0 1.2 1.1

5.2 5.7 5.5

2.5 2.0 2.3

5.6 4.8 5.2

1.8 1.6 1.7

Vaquero 32 Drop

No Drop

38 Drop

No Drop

Avg Drop

No Drop

84.0 72.8

0.0 0.0

81.5 69.1

6.0 1.2

82.7 71.0

0.0 0.0

78.4

0.0

75.3

3.6

76.8

0.0

80.4 40.8 60.6

0.0 0.0 0.0

78.9 34.1 56.5

41.7 19.4 30.6

79.6 37.4 58.5

0.0 0.0 0.0

5.6 5.0 5.3

0.0 0.0 0.0

5.6 3.3 4.5

2.5 2.0 2.3

5.6 4.2 4.9

0.0 0.0 0.0

Bandolero 32 Drop

No Drop

38 Drop

No Drop

Avg Drop

No Drop

77.8 83.3

0.0 2.2

83.3 86.7

0.0 0.0

80.6 85.0

0.0 1.1

80.5

1.1

85.0

0.0

82.8

0.6

76.3 42.8 59.5

0.0 12.8 6.4

76.6 67.2 71.9

0.0 0.0 0.0

76.4 55.0 65.7

0.0 6.4 3.2

5.0 4.9 5.0

0.0 2.0 1.0

5.1 5.0 5.0

0.0 0.0 0.0

5.1 4.9 5.0

0.0 1.0 0.5

Overall 32 Drop 84.8 81.6 81.0 83.1 46.7 64.9 5.5 4.7 5.1averages No Drop

38 Drop

No Drop

Avg Drop

No Drop

1.3 1.4

80.5 85.9

3.0 0.6

82.7 81.6

2.2 1.0

1.4

83.2

1.8

82.2

1.6

10.8 7.7 9.3

80.2 59.6 69.9

20.9 9.7 15.3

81.6 53.1 67.3

15.8 8.7 12.3

0.6 0.8 0.7

5.5 4.8 5.2

1.3 1.0 1.1

5.5 4.7 5.1

0.9 0.9 0.9

LSD (0.05) Handling

Temperature

Time

Temp. X TimeVariety

Temp. X VarietyTime X Variety

Temp. X Time X Variety

3.9

NS

NS

NS

NS

NS

NS

NS

5.1

1.7

1.7

2.4

2.4

3.3

3.3

4.7

0.3

NS

0.1

NS

0.2

0.2

0.2

0.3

49

EVALUATION OF OVERWINTERING ONION FORPRODUCTION IN THE TREASURE VALLEY, 2003-2004 TRIAL



Introduction

The objective of this trial was to evaluate yellow and red onion varieties for overwinteringproduction in the Treasure Valley. Bulb yield, grade, and pungency were evaluated. Sevenyellow varieties and three red varieties were planted in August 2003 and were harvestedand graded in June 2004.

Methods

The onions were grown on a field of Owyhee silt loam located northeast of the MaiheurExperiment Station on Railroad Ave. between Highway 201 and Alameda Drive. Seed of10 varieties was planted in double rows spaced 3 inches apart at 9 seeds/ft of single row onAugust 25, 2003. Each double row was planted on beds spaced 20 inches apart with acustomized planter using John Deere Flexi Planter units equipped with disc openers. OnOctober 21, 2003, alleys 4 ft wide were cut between plots, leaving plots 23 ft long. OnOctober 22 the seedlings were hand thinned to a plant population of 95,000 plants/acre(6.6-inch spacing between individual onion plants). All cultural practices were performed bythe grower. The experimental design was a randomized complete block with five replicates.

Onions in each plot were evaluated subjectively for maturity on June 14, 2004 by visuallyrating the percentage of onions with the tops down and the percent dryness of the foliage.The percent maturity was calculated as the average of the percentage of onion with topsdown and the percent dryness. The number of bolted onion plants in each plot wascounted.

Onions from the middle two rows in each plot were lifted, topped by hand, and bagged onJune 21, 2004. The onion bags were transported to a shed at the Maiheur ExperimentStation. On June 23 the onions were graded.

Before grading, all bulbs from each plot were counted to determine actual plant populationsat harvest. During grading, bulbs were separated according to quality: bulbs withoutblemishes (No. is), split bulbs (No. 2s), neck rot (bulbs infected with the fungus Boti'ytis all/iin the neck or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), andblack mold (bulbs infected with the fungus Aspergillus niger). The No. 1 bulbs were gradedaccording to diameter: small (<2.25 inch), medium (2.25-3 inch), (3-4 inch), colossal(4-4.25 inch), and supercolossal (>4.25 inch). Bulb counts/50 lb of supercolossal onions

50

were determined for each plot of every variety by weighing and counting all supercolossalbulbs during grading.

Ten randomly chosen bulbs from each plot were shipped on June 25 via UPS ground toVidalia Labs International (Collins, GA). The bulb samples were analyzed for pyruvic acidcontent on July 2. Bulb pyruvic acid content is a measure of pungency with the unit beingmicromoles pyruvic acid/g of fresh weight (pmole/g FW). Onion bulbs having a pyruvateconcentration of 5.5 or less are considered sweet according to Vidalia Labs sweet onioncertification specifications.

On July 6, bulbs from each plot were rated subjectively for exterior quality. Bulbs wererated for skin retention, exterior thrips damage, and rot.

Varietal differences were compared using ANOVA and least significant differences at the 5percent probability level, LSD (0.05). Varieties were listed by company in alphabeticalorder. The LSD (0.05) values should be considered when comparisons are made betweenvarieties for significant differences in performance characteristics. Differences betweenvarieties equal to or greater than the LSD (0.05) value for a characteristic should existbefore any variety is considered different from any other variety in that characteristic.

Results

Grower practices adequately controlled thrips during seedling emergence and early plantgrowth, critical phases for successful overwintering onion production in the Treasure Valley.The winter of 2003-2004 in the Treasure Valley was mild, with the lowest temperature of-1°F on January 5, 2004. In spite of that, plant populations were below the target of 95,000plants/acre for all varieties, suggesting that a higher population should have been left afterthinning. Plant populations ranged from 38,863 plants/acre for 'Musica' to 71,362plants/acre for 'T-420' (Table 1).

Total yield averaged 440 cwt/acre and ranged from 360 cwt/acre for 'Electric' to 606cwt/acre for 'Stansa' (Table 1). Stansa and T-420 had the highest total yield. Marketableyield averaged 391 cwt/acre and ranged from 291 cwt/acre for 'XON-305Y' to 545 cwt/acrefor Stansa. Supercolossal-size onion yield averaged 18 cwtlacre and ranged from 2cwt/acre for 'MKS-816' to 79 cwtlacre for Stansa. Stansa had the highest yield ofsupercolossal bulbs. Not counting supercolossals, colossal-size onion yield averaged 179cwt/acre and ranged from 14.4 cwt/acre for 'Desert Sunrise' to 179 cwtlacre for Stansa.Stansa had the highest colossal bulb yields.

Maturity on June 14 ranged from 0 percent for 'Garnet' to 79 percent for 'MKS-801' (Table2). Varieties 1-420, XON-305Y, MKS-801, and MKS-816 had bulb pyruvate concentrationslow enough (<5.5 pmoles/g FW) to be classified as sweet onions. MKS-801 had the lowestpyruvate concentration. Subjective evaluation of skin retention ranged from 1.6 (worst = 0)for MKS-801 to 4.4 (best = 10) for T-420. Subjective evaluation of thrips damage rangedfrom 5.8 (most thrips = 10) for Desert Sunrise to 1.4 (fewest thrips = 0) for 'Hi Keeper'.

51

Table 1. Performance data for onion varieties planted in August 2003 and harvested in June 2004, Malheur Experiment Station,Oregon State University, Ontario, OR.

plants/acre --- cwt/acre cwt/acre #/50 lb % of total -- cwt/acre --yield

Bulb Plant TotalMarketable yield by grade Super-

colossalNon-marketable yield

Company Entry name color population yield Total >41/4 in 4-4% in 3-4 in 2%-3 in counts Total rot No. 2s Small

A. Takii Hi Keeper Y 67,044 518.5 482.6 4.7 109.1 334.2 34.6 37 0.0 29.8 5.9T-420 Y 71,362 562.2 515.3 13.1 107.5 365.1 29.6 35 0.2 40.5 5.0

Bejo Electric R 54,204 359.8 341.3 3.3 41.9 270.7 25.4 60 0.7 8.2 7.5Musica Y 38,863 366.2 320.9 39.8 107.9 165.4 7.6 44 0.6 38.6 4.4Stansa Y 64,431 605.7 545.3 78.9 179.4 273.6 13.3 37 0.3 54.9 3.4

D. Palmer Desert Sunrise R 58,294 440.6 326.9 3.5 14.4 271.3 37.8 33 0.0 105.9 7.8Sakata XON-305Y Y 46,817 376.5290.8 18.4 59.6 187.6 25.1 33 0.8 76.3 6.4Scottseed Garnet R 56,249 377.5 352.8 12.1 43.8 267.7 29.2 54 0.4 17.1 6.2

MKS-801 Y 58,522 373.1 344.8 5.1 27.8 265.4 46.6 35 1.2 16.3 7.6MKS-816 Y 65,453 417.5 387.6 1.7 19.0 322.9 43.8 33 0.3 21.9 6.5

LSD (0.05) 13,182 63.6 63.5 17.3 30.0 64.0 17.4 NS NS 25.4 5.1

Table 2. Mand rot, 0 =

aturity, pyruvateworst and 10 =

concentration, andbest for skin retenti

subjective rating of exteon, Maiheur Experiment

nor bulb quality: 0 = fewest and 10 = most for thrips damageStation, Oregon State University, Ontario, OR, 2004.

Exterior bulb qualitySkin retention Thrips damage RotCompany Entry name

Bulb Maturcolor 14 June

%

ity PyruvateBolters concentration#/plot pmoles/g FW

A. Takii Hi Keeper Y 66 0 6.38 3.2 1.4 1.2T-420 Y 67 0 5.18 4.4 3.6 1.4

Bejo Electric R 0 0 7.60 5.0 4.0 1.0Musica Y 6 1.2 6.26 3.6 2.4 1.4Stansa Y 8 1.2 6.80 3.8 3.2 2.2

D. Palmer Desert Sunrise R 47 0.2 5.70 2.6 5.8 2.4Sakata XON-305Y Y 44 2.8 5.34 2.4 2.6 1.6Scottseed Garnet R 0 0.4 7.08 3.4 4.4 1.0

MKS-801 Y 79 0 4.36 1.6 2.0 4.0MKS-816 Y 78 0 4.64 1.8 2.4 2.6

LSD (0.05) 6 0.7 0.61 1.7 1.8 NS

WEED CONTROL IN ONION WITH POSTEMERGENCE HERBICIDES



Introduction

Weed control is essential for the production of marketable onions. Weed control inonions is difficult compared to many crops because of the lack of a complete cropcanopy and limited herbicide options. Chateau® (flumioxazin), formerly called Valor®,and Nortron® (ethofumesate) are two experimental herbicides that have been evaluatedfor use in onions in past research trials. Trials were conducted this year to determinethe benefits of using these experimental herbicides in postemergence herbicidecombinations and compare their performance to registered herbicide combinations.

Methods

General ProceduresTrials were conducted at the Malheur Experiment Station to evaluate experimental andregistered herbicides for weed control and onion tolerance. Trials were conductedunder furrow irrigation. On March 25, onions (cv. Vaquero', Nunhems, Parma, ID) wereplanted at 3.7-inch spacing in double rows on 22-inch beds. Plots were 4 rows wideand 27 ft long and arranged in a randomized complete block design with fourreplications. Lorsban® was applied in a 6-inch band over each double row at 3.7oz/1,000 ft of row. Onions were sidedressed with 175 lb nitrogen (N), 30 lb phosphorus(P), 35 lb sulfate, 38 lb sulfur (S), 2 lb Zinc (Zn), 3 lb manganese (Mn), and 1 lb boron(B)/acre on June 3. Registered insecticides and fungicides were applied for thrips anddowny mildew control.

Herbicide treatments were applied with a CO2-pressurized backpack sprayer.Preemergence applications and postemergence grass herbicides were applied at 20gal/acre at 30 psi and postemergence treatments were applied at 40 gal/acre at 30 psi.All plots were treated with a preemergence application of Roundup® (glyphosate) at0.75 lb ai/acre plus Prow®l (pendimethalin) at 1.0 lb ai/acre on April 5 and apostemergence application of Poast® (sethoxydim) at 0.19 lb ai/acre plus crop oilconcentrate (COC) (1.0% v/v) on June 16. Postemergence treatments were applied totwo-leaf onions on May 6, two- to three-leaf onions on May 14, and to five-leaf onionson June 2. In the Chateau application timing trial, a separate application of Chateauwas made to three-leaf onions on May 18. Weed control and onion injury wereevaluated throughout the season. Onions were harvested September 16 and 17 andgraded by size on October 1-4.

54

Data were analyzed using analysis of variance and means were separated using aprotected least significant difference (LSD) at the 5 percent level (0.05).

Comparison of Postemergence Chateau or Goal CombinationsChateau and Goal® (oxyflurofen) were applied in combinations with Buctril(bromoxynil) to evaluate weed control and onion tolerance. Buctril, Goal, and Chateauwere evaluated at two rates. Comparisons of Goal or Chateau with Buctril includedseveral combinations of herbicides and rates. Additional treatments included a splitapplication of Chateau applied to two-leaf and again to three-leaf onions, and acomparison of Buctril plus Chateau treatments following preemergence applications ofRoundup, Prowl, and Dacthal® (DCPA).

Application Timings for ChateauChateau was applied at two rates in combination with Buctril to two-leaf or three-leafonions. Chateau treatments were compared to Goal plus Buctril. Additional treatmentsincluded Chateau in a separate application 4 days after the Buctril application at thethree-leaf application timing.

Addition of Nortron to Postemergence TreatmentsThis trial was conducted to determine if the addition of Nortron to postemergenceherbicide applications would improve weed control. Each treatment was applied with orwithout Nortron added to the two-leaf and three-leaf applications at either 0.25 or 0.5 lbai/acre. One treatment evaluated Outlook® (dimethenamid-P) added to the two-leafapplication and Nortron added to the three-leaf application.


Preemergence herbicides worked fairly well due to rainfall in April. Adequate rainfallalso ensured that weeds were actively growing when postemergence treatments wereapplied.

Comparison of Postemergence Chateau or Goal CombinationsBecause the preemergence application of Prowl was so effective, there were nodifferences in weed control between any of the postemergence herbicide treatments(Table 1). Control of all species was 85 percent or greater. There were also nodifferences in onion injury among treatments. This is surprising as there were largedifferences in the herbicide rates applied for different treatments. There were a fewdifferences in onion yields, with higher yields resulting from treatments with additionalsoil-active herbicides applied or with higher rates (Table 2).

Application Timings for ChateauTreatment with Chateau combined with Buctril when applied either to two-leaf or three-leaf onions did not cause greater injury than combinations of Goal plus Buctril (Table 3).When Chateau was applied alone 4 days after Buctril was applied to three-leaf onions,injury increased significantly. By July 21 there were no differences in onion injury

55

among treatments. The injury caused by the delayed application of Chateau wasprobably related to wet cool weather that occurred after the Buctril application and priorto the Chateau application. Pigweed (red root pigweed and Powell amaranth), commonlambsquarters, hairy nightshade, and barnyardgrass control was not different amongherbicide treatments and was 88 percent control or greater. Kochia control wassignificantly greater with treatments that contained Chateau tank-mixed with Buctril andapplied at either the two-leaf or three-leaf timing compared to Buctril plus Goal.Treatments where Chateau was applied alone following the Buctril application to three-leaf onions did not control weeds better than Buctril plus Goal.

There were few significant differences in onion yields between herbicide treatments,with marketable yields ranging from 1,107 to 1,459 cwtlacre.

Addition of Nortron to Postemergence TreatmentsOnion injury was not different among treatments on either evaluation date (Table 5).Pigweed, hairy nightshade, and barnyardgrass control was similar among herbicidetreatments and was 89 percent or higher. The addition of Nortron at either rate toBuctril significantly increased common lambsquarters control, but control was similar tothat provided by Goal plus Buctril. There was no improvement in commonlambsquarters control when Nortron was added to Buctril plus Goal. Kochia controlwas less when Buctril was applied alone compared to treatments containing Buctril plusNortron or Goal or both. A few of the treatments containing Nortron produced moresupercolossal onions than did Buctril alone, but yields were similar to the otherherbicide treatments (Table 6). Nortron is useful for improving weed control in onionbut in this trial did not provide greater benefits than the currently registered herbicides.

56

Table 1.Oregon

Onion injury andState University,

weed control fromOntario, OR, 2004.

Goal® or Chateau® combinations with Buctril®, Maiheur Experiment Station,

Treatmentlb

Rate

ai/acre

Timing*

Leaf

Injury Weed controlt

Common Hairy Barnyard-

5-24 6-9 Pigweed Iambsguarters nightshade Kochia grass0/

Untreated

Roundup + Prowl 0.75 + 1.0 PRE 24 28 86 90 96 95 100

Buctril 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf


Buctril 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup+Prowl 0.75+ 1.0 PRE 25 18 96 95 96 100 100

Buctril + Chateau 0.125 + 0.063 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf



Roundup+ Prowl 0.75+ 1.0 PRE 21 16 93 98 96 100 99





Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf





Table I (continued).Onion injury and weed control from Goal® or Chateau® combinations with Buctril®, MaiheurExperiment Station, Oregon State University, Ontario, OR, 2004.

Treatment Rate Timing*

Injury Weed controlt

Common Hairy Barnyard-5-24 6-9 Pigweedt lambsguarters nightshade Kochia grass

Ibal/acre Leaf 0/

Roundup + Prowl 0.75 + 1.0 PRE 28 19 90 93 94 100 95Buctril + Goal 0.25 + 0.25 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leafRoundup+Prowl 0.75+ 1.0 PRE 25 18 95 97 97 88 100Buctril + Chateau 0.125 + 0.047 2-leafBuctril + Chateau 0.25 + 0.047 3-leafGoal 0.25 5-leaf

Roundup + Dacthal + Prowl 0.75 + PRE 27 21 97 92 100 96 100Buctril + Chateau 7.5 + 0.6 2-leafBuctril + Goal 0.25 + 0.094 3-leafGoal 0.125 + 0.25 5-leaf

Roundup + Dacthal + Prowl 0.75+7.5 + 0.6 PRE 27 18 96 98 100 100 100Buctril + Chateau 0.125 + 0.094 2-leafBuctril + Goal 0.125 + 0.25 3-leafGoal 0.25 5-leaf

Roundup + Dacthal + Prowl 0.75 + 7.5 + 0.6 PRE 24 20 96 100 98 100 95Buctril + Chateau 0.25 + 0.094 2-leafBuctril + Goal 0.125 + 0.125 3-leafGoal 0.25 5-leaf

LSD (P = 0.05) -- -- NS NS NS NS NS NS NS

*Preemergence (PRE) treatments were applied on April 5, two-leaf (2-leaf) on May 6, three-leaf (3-leaf) on May 14, and five-leaf (5-leaf) on June 2.tweedcontrol ratings were taken September 2.tPigweed is a combination of redroot pigweed and Powell amaranth.

Table 2. Onion yield in response to Goal® or Chateau® combinations with Buctril®, Malheur Experiment Station, OregonState University, Ontario, OR, 2004


Onion

Small Medium Jumbo Colossal S. Colossal Marketable

cwtlacreIbal/acre LeafUntreated 0 0 0 0 0 0

Roundup + Prowl 0.75 + 1.0 PRE 5 28 626 345 30 1029Buctril 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 4 13 527 540 150 1,229Buctril 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup+Prowl 0.75+ 1.0 PRE 7 16 481 522 141 1,160Buctril + Chateau 0.125 + 0.063 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 6 17 559 510 123 1,208Buctril + Chateau 0.125 + 0.094 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf



Roundup+Prowl 0.75+ 1.0 PRE 7 48 595 348 111 1,101Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 3 13 497 524 181 1,216Buctril + Goal 0.125 + 0.25 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf


Table 2 (continued). Onion yield in response to Goal® or Chateau® combinations with Buctril®,Station, Oregon State University, Ontario, OR, 2004.

Malheur Experiment


Onion yieldt


cwt/acrelbai/acre Leaf


Roundup+Prowl 0.75+1.0 PRE 5 23 600 441 128 1,192Buctril + Chateau 0.125 + 0.047 2-leafBuctril + Chateau 0.25 + 0.047 3-leafGoal 0.25 5-leaf

Roundup + Dacthal + Prowl 0.75 + 7.5 + 0.6 PRE 3 18 461 552 207 1,238Buctril + Chateau 0.25 + 0.094 2-leafBuctril + Goal 0.125 + 0.25 3-leafGoal 0.25 5-leafRoundup + Dacthal + Prowl 0.75 + 7.5 + 0.6 PRE 4 15 450 596 225 1,285Buctril + Chateau 0.125 + 0.094 2-leafBuctril + Goal 0.125 + 0.25 3-leafGoal 0.25 5-leafRoundup + Dacthal + Prowl 0.75 + 7.5 + 0.6 PRE 4 18 484 552 168 1,222Buctril + Chateau 0.25 + 0.094 2-leafBuctril + Goal 0.125 + 0.125 3-leafGoal 0.25 5-leaf

LSD(P=0.05) -- -- 5 18 185 180 122 193

two-leaf (2-leaf) on May 6, three-leaf (3-leaf) on May 1 4, and five-leaf (5-leaf) on June 2.*preemergence (PRE) treatment applied on April 5,tonions were harvested on September 16 and 17.

Table 3. Weed control and onion injury in response toOregon State University, Ontario, OR, 2004.

Chateau® application timings, Malheur Experiment Station,


InjuryCommon

5-24 6-21 Pigweedt lambsquarters

Weed controlt

.

Hairy Barnyard-nightshade Kochia grass

Ibal/acre Leaf 0/

Untreated -- -- -. -- -- -- -- -- --Roundup + Prowl 0.75 + 1.0 PRE 24 16 89 90 97 72 100Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leafRoundup + Prowl 0.75 + 1.0 PRE 26 19 96 90 100 96 99Buctril + Chateau 0.125 + 0.063 2-leafBuctril + Goal 0.25 + 0125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 26 21 94 89 100 96 100Buctril + Chateau 0.125 + 0.094 2-leafBuctril ÷ Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 29 21 97 88 100 99 98Buctril + Goal 0.125 + 0.125 2-leafBuctril + Chateau 0.25 + 0.063 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 29 21 91 91 99 93 100Buctril + Goal 0.125 + 0.125 2-leafBuctril + Chateau 0.25 + 0.094 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 34 20 92 89 100 77 100Buctril + Goal 0.125 + 0.125 2-leafBuctril 0.25 3-leafChateau 0.063 3-leaf (S)Goal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PRE 36 21 92 91 98 82 100Buctril + Goal 0.125 + 0.125 2-leafBuctril 0.25 3-leafChateau 0.094 3-leaf (S)Goal 0.25 5-leaf

LSD (P 0.05) -- -- 5 NS NS NS NS 15 NS

two-leaf (2-leaf) on May 6, three-leaf (3-leaf) on May 14, th ree-leaf separate (3-leaf (S)) on May 18, and five-leaf (5-leaf)*preemergence (PRE) treatments were applied on April 5,on June 2.tWeed control ratings were taken September 2.tpigweed is a combination of redroot pigweed and Powell amaranth.

*Preemergence (PRE) treatments were applied on Aprit 5,on June 2.

were harvested on September16 and 17.

Table 4. Onion yield in response to Chateau® application timings,Ontario, OR, 2004

Maiheur Experiment Station, Oregon State University,


Onion


Untreated

lbailacre

--

Leaf

--

cwtlacre

0 0 0 0 0 0

Roundup+ ProwlBuctril + GoalBuctrit + GoalGoal

0.75+1.00.125 + 0.1250.25 + 0.125

0.25

PRE2-leaf3-leaf5-leaf

4 18 639 385 75 1,117

Roundup+ ProwlBuctril + ChateauBuctril + GoalGoal

0.75+1.00.125 + 0.0630.25 + 0.125

0.25


4 16 519 535 110 1,179

Roundup + ProwlBuctril + ChateauBuctril + GoalGoal

0.75 + 1.00.125 + 0.0940.25 + 0.125

0.25


4 28 592 386 87 1,093

Roundup + ProwlBuctril + GoalBuctril + ChateauGoal

0.75 + 1.00.125 + 0.1250.25 + 0.063

0.25


4 22 602 501 90 1,215

Roundup + ProwlBuctril + GoalBuctril + ChateauGoal

0.75 + 1.00.125 + 0.1250.25 + 0.094

0.25


2 21 640 713 86 1,459

Roundup + ProwlBuctrit + GoalBuctrilChateauGoal

0.75 + 1.00.125 + 0.125

0.250.0630.25

PRE2-leaf3-leaf

3-leaf (5)5-leaf

6 30 661 345 70 1,107

Roundup + ProwlBuctril + GoalBuctrilChateauGoal

0.75 + 1.00.125 + 0.125

0.250.0940.25

PRE2-teaf3-leaf

3-leaf(S)5-leaf

6 30 584 423 109 1,145

LSD (P = 0.05) -- -- 2 18 99 302 64 333

two-leaf (2-leaf) on May 6, three-leaf (3-leaf) on May 14, three-leaf separate (3-leaf(S)) on May 18, and five-leaf (5-leaf)

Table 5. Onion injury and weed control in response to the addition of Nortron® to postemergenceand Goal®, Maiheur Experiment Station, Oregon State University, Ontario, OR, 2004.

applications of Buctril®


Weed

InjuryCommon Hairy Barnyard-

5-24 6-9 Pigweedt lambsquarters nightshade Kochia grass0/

lbai/acre Leaf

Untreated -- -- -- -- -- -- -- -- --

Roundup + Prowl 0.75 + 1.0 PREBuctril 0.125 2-leaf 20 18 89 89 100 76 100Buctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PREBuctril + Goal 0.125 + 0.125 2-leaf 25 21 93 95 100 89 100Buctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PREBuctril + Nortron 0.125 + 0.25 2-leaf 23 16 100 100 97 95 100Buctril + Goal + Nortron 0.25 + 0.125 + 0.25 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PREBuctril + Nortron 0.125 + 0.5 2-leaf 27 22 90 100 100 97 100Buctril + Goal + Nortron 0.25 + 0.125 + 0.5 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PREBuctril + Goal + Nortron 0.125 + 0.125 + 0.25 2-leaf 28 23 93 93 100 94 100Buctril + Goal + Nortron 0.25 + 0.125 + 0.25 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PREBuctril + Goal + Outlook 0.125 + 0.125 + 0.84 2-leaf 25 18 100 100 100 98 100Buctril + Goal + Nortron 0.25 + 0.125 + 0.25 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.0 PREBuctril + Goal + Nortron 0.125 + 0.125 + 0.5 2-leaf 28 24 97 99 97 100 97Buctril + Goal + Nortron 0.25 + 0.125 + 0.5 3-leafBuctril + Goal 0.125 + 0.25 5-leaf

LSD (P = 0.05) -- -- NS NS NS 7 NS 13 NS

two-leaf (2-Ieaf) on May 6, three-leaf (3-leaf) on May 14, and five-leaf (5-leaf) on June 2.*preemergence (PRE) treatments were applied on April 5,tWeed control ratings were taken September 2.tPigweed is a combination of redroot pigweed and Powell amaranth.

Table 6. Onion yield in response to the addition of Nortron® to postemergence applications of Buctril® andExperiment Station, Oregon State University, Ontario, OR, 2004.

Onion vieldt

Goal®, Malheur

*preemergence (PRE) treatment applied on April 5, two-leaf (2-leaf) on MaytOnions were harvested on September 16 and 17.

14, three-leaf (3-leaf) on May 18, and five-leaf (5-leaf) on June 2.

Treatment Rate Timing* Small Medium Jumbo Colossal S. Colossal Marketable

lb al/acre

0.75 + 1.00.125

0.25 + 0.1250.25

0.75 + 1.00.125 + 0.1250.25 + 0.125

0.25

Leaf



0 0 0 0 0Untreated

Roundup + ProwlBuctrilBuctril + GoalGoal

Roundup + ProwlBuctril + GoalBuctril + GoalGoal

Roundup + ProwlBuctril + NortronBuctril + Goal + NortronGoal

Roundup + ProwlBuctril + NortronBuctril + Goal + NortronGoal

Roundup + ProwlBuctril + Goal + NortronBuctril + Goal + NortronGoal

Roundup + ProwlBuctril + Goal + OutlookBuctril + Goal + NortronGoal

Roundup + ProwlBuctril + Goal + NortronBuctril + Goal + NortronBuctril + Goal

LSD (P = 0.05)

PRE

0

S

7

6

3

4

4

8

4

0.75 + 1.00.125 + 0.25

0.25 + 0.125 + 0.250.25


0.75 + 1.00.125+ 0.5

0.25 + 0.125 + 0.50.25

2-leaf3-leaf5-leaf

0.75 + 1.00.125 + 0.125 + 0.250.25 + 0.125 + 0.25

0.25


0.75 + 1.00.125 + 0.125 + 0.840.25 + 0.125 + 0.25

0.25


0.75 + 1.00.125 + 0.125 + 0.50.25 + 0.125 + 0.5

0.125 + 0.25


45

37

29

18

33

17

21

16

689

609

693

597

640

614

662

113

225

354

349

424

363

475

440

237

12

65

60

111

72

117

97

66

971

1,066

1,130

1,150

1,107

1,223

1,219

278

SOIL-ACTIVE HERBICIDE APPLICATIONS FOR WEED CONTROL IN ONION



Introduction

Weed control is essential for the production of marketable onions. Only a fewherbicides are registered for preemergence application in onion. Effectivepreemergence herbicides can control weeds as they germinate and reduce the size andnumber of weeds that are present when onions are large enough to toleratepostemergence herbicide applications. This research evaluated registered andexperimental herbicides for preemergence weed control in onion.

Methods

General ProceduresA trial was conducted at the Malheur Experiment Station under furrow irrigation. OnMarch 25, onions (cv. 'Vaquero', Nunhems, Parma, ID) were planted at 3.7-inchspacing in double rows on 22-inch beds. Plots were 4 rows wide and 27 ft long andarranged in a randomized complete block design with 4 replicates. Lorsban® wasapplied in a 6-inch band over each double row at 3.7 oz/1 ,000 ft of row. Onions weresidedressed with 175 lb nitrogen, 30 lb phosphorus, 35 lb sulfate, 38 lb elementalsulfur, 2 lb zinc, 3 lb manganese, and 1 lb boron/acre on June 3. Registeredinsecticides and fungicides were applied for thrips and downy mildew control.

Preemergence (PRE) applications of Prowl® (pendimethalin), Nortron® (ethofumesate),and Outlook® (dimethenamid-P) in combination with Roundup (glyphosate) wereevaluated for weed control and onion tolerance. Each product was evaluated at tworates. Combinations of Prowl with Nortron or Outlook were also evaluated. Prowl andProwl H20® (a new water-based formulation) were also applied to onions at the flag leafstage following Roundup applied PRE. Prowl H20 was also combined with Outlookapplied at the flag leaf stage following a PRE application of Roundup. Preemergencetreatments and other applications of soil-active herbicides were compared to plotswhere only Roundup was applied preemergence.

Herbicide treatments were applied with a C02-pressurized backpack sprayer.Preemergence applications were applied at 20 gal/acre at 30 psi. Postemergenceapplications were applied at 40 gal/acre at 30 psi. Preemergence treatments wereapplied on April 5, two-leaf on May 6, three-leaf on May 14, and five-leaf on June 2.

65

All plots received Poast® (sethoxydim) at 0.19 lbs ai/acre plus crop oil concentrate(COC) (1 qt/acre) on June 16 to control grasses. Weed control and onion injury wereevaluated throughout the season. Onions were harvested September 16 and 17 andgraded by size on October 1-4.

Data were analyzed using analysis of variance and means were separated using aprotected least significant difference (LSD) at the 5 percent level (0.05).


Preemergence and postemergence treatments were effective because of rain andactively growing weeds at the time herbicides were applied. Injury was similar amongtreatments except for plots treated with a tank mixture of Buctril, Outlook, and Chateau,which had significantly more injury than all other treatments on May 24 and at the laterevaluation on June 9 (Table 1). Pigweed (redroot pigweed and Powell amaranth)control was similar among herbicide treatments and ranged from 84 to 99 percent.Common lambsquarters control was improved with preemergence applications of Prowlcompared to plots treated only with Roundup PRE. Outlook and Nortron did notsignificantly increase common lambsquarters control compared to Roundup alone.Hairy nightshade control was greater than 90 percent and barnyardgrass greater than96 percent for all herbicides. Kochia control was significantly greater with PRE Prowl orNortron compared to Outlook. However, the high rate of Outlook improved kochiacontrol compared to Roundup alone PRE. This year, delaying Prowl or Prowl plusOutlook combinations until the flag leaf stage provided similar control to preemergenceapplications. If these treatments are as effective as the PRE applications, thenapplications to flag leaf onions provide an increased level of crop safety compared toPRE applications. Treatments with Prowl applied PRE or to flag leaf onions followed byapplications of Outlook to two-leaf onions also effectively controlled all weeds. TheProwl label allows applications to flag leaf onions and the Outlook label allowsapplications to two-leaf onions.

Roundup alone PRE and Roundup plus Outlook (0.66 lb ai/acre) produced highermedium onion yields and lower colossal, total, and marketable onion yields comparedto all the other treatments (Table 2). The combination of Prowl plus Outlook PRE hadamong the lowest number of onion bulbs per acre and was less than plots withRoundup alone PRE or applications of Prowl made to flag leaf onions. This resultillustrates the potential to reduce onion stand with PRE applications of soil-activeherbicides. Even with the reduced number of onion bulbs, this treatment producedyields similar to all other treatments. Only plots with reduced weed control hadsignificantly lower yields. The increased weed control and subsequent increase inonion yields from plots receiving a PRE or flag leaf application of a soil-active herbicidedemonstrates the importance of soil-active herbicides for reducing weed germinationand growth prior to when postemergence herbicide applications can be made.

66

Table 1. Onion injury and weed control in response to applications of Outlook®, Nortron®, and Prowl®, MaiheurExperiment Station, Oregon State University, Ontario, OR, 2004.

Treatment Rate Timing•

Injury Weed

5-24 6-9 PigweedtCommon

lambsquartersHairy

nightshade Kochia Barnyardgrass

lbai/acre Leaf 0/

Untreated

Roundup + Outlook 0.75 + 0.656 PRE 25 16 87 77 100 73 100

Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leafRoundup + Outlook 0.75 + 0.843 PRE 25 17 95 88 100 85 100


Roundup + Nortron 0.75 + 1.0 PRE 26 19 88 85 91 96 98


Roundup + Nortron 0.75 + 2.0 PRE 27 16 93 90 100 100 100




Roundup + Prowl 0.75 + 1.5 PRE 26 17 95 98 100 99 100Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup 0.75 PRE 25 16 84 77 98 69 99


Roundup + Prowl + Nortron 0.75 + 1.0 + 1.0 PRE 26 16 99 100 100 99 97


Roundup + Prowl + Outlook 0.75 + 1.0 + 0.843 PRE 26 18 97 100 95 98 100


Table 1 (continued). Onion injury and weed control in response to applications of Outlook®, Nortron®, and Prowl®,Maiheur Exreriment Station, Oregon State University, Ontario, OR, 2004.

Treatment Rate Timing.

Iniury Weed controlt

Common Hairy5-24 6-9 tPigweed lambsguarters nightshade Kochia Barnyardgrass

lbai/acre Leaf 0/

RoudupProwl + OutlookBuctril + GoalBuctril + GoalGoal

0.751.0 + 0.843

0.125 + 0.1250.25 + 0.125

0.25

PREflag

2-leaf3-leaf5-leaf

26 17 96 93 99 97 100

RoundupProwl H20 + OutlookBuctril + GoalBuctril + GoalGoal

0.751.0 + 0.843

0.125 + 0.1250.25 + 0.125

0.25

PREflag

2-leaf3-leaf5-leaf

26 18 95 92 100 88 100

RoundupProwlBuctril + Goal + OutlookBuctril + GoalGoal

0.751.0

0.125 + 0.125 + 0.8430.25 + 0.125

0.25

PREflag

2-leaf3-leaf5-leaf

25 16 88 83 97 100 100

RoundupProwl H2OBuctril + Goal + OutlookBuctril + GoalGoal

0.751.0

0.125 + 0.125 + 0.8430.25 + 0.125

0.25

PREflag

2-leaf3-leaf5-leaf

26 17 92 92 100 100 100

Roundup+ ProwlBuctril + Goal + OutlookBuctril + GoalGoal

0.75+ 1.00.125 + 0.125 + 0.843

0.25 + 0.1250.25


24 17 97 98 100 100 99

Roundup+ ProwlBuctril + Chateau + OutlookBuctril + GoalGoal

0.75+ 1.00.125 + 0.063 + 0.843

0.25 + 0.1250.25


39 27 98 100 100 100 96

LSD (0.05) -- -- 2 3 12 12 6 10 3

two-leaf (2-le af) on May 6, three-leaf (3-leaf) on May 14, and five-leaf (5-leaf) on June 2.*preemergence (PRE) treatments were applied on April 5,tWeed control was evaluated on September 2.

is a combination of redroot pigweed and Powell amaranth.

Table 2. Onion yield in response to applications of Outlook®, Nortron®, and Prowl®, Maiheur Experiment Station, OregonState University, Ontario, OR, 2004

Treatment Rate Timing*Onion yieldt


lbai/acre Leafcwtlacre

Untreated

5 32

9 22

Roundup + Outlook 0.75 + 0.656 PRE 8 59 650 151 25 884


Roundup + Outlook 0.75 + 0.843 PRE 9 23 726 340 22 1111

Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leafRoundup + Nortron 0.75 + 1.0 PRE 9 31 624 369 60 1085


Roundup + Nortron 0.75 + 2.0 PRE 633 379 61 1105

Buctril ÷ Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leafRoundup+Prowl 0.75+ 1.0 PRE 695 412 70 1199Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl 0.75 + 1.5 PRE 640 357 73 1092


Roundup 0.75 PRE 11 678 128 10 874Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

Roundup + Prowl + Nortron 0.75 + 1.0 + 1.0 PRE 11 555 498 101 1176


Roundup + Prowl + Outlook 0.75 + 1.0 + 0.843 PRE 543 423 110 1095Buctril + Goal 0.125 + 0.125 2-leafBuctril + Goal 0.25 + 0.125 3-leafGoal 0.25 5-leaf

7 23

59

23

4 20

Table 2 (continued). Onion yield in response to applications of Outlook®, Nortron®, and Prowl®, Maiheur ExperimentStation, Oreqon State University, Ontario, OR, 2004.

Treatment Rate Small

Onion yieldt

Medium Jumbo Colossal S. Colossal Marketablecwt/acre

RoundupProwl + OutlookBuctril + GoalBuctri! + GoalGoal

RoundupProwl H2O + OutlookBuctril + GoalBuctril + GoalGoal

RoundupProwlBuctril + Goal +OutlookBuctril + GoalGoal

RoundupProwl H2OBuctril + Goal + OutlookBuctril + GoalGoal

Roundup + ProwlBuctril + Goal + OutlookBuctril + GoalGoal

Roundup + ProwlBuctril + Chateau + OutlookBuctril + GoalGoal

LSD (0.05)

0.751.0 + 0.843

0.125 + 0.1250.25 + 0.125

0.25

0.751.0 + 0.843

0.125 + 0.1250.25 + 0.125

0.25

0.751.0

0.125 + 0.125 + 0.8430.25 + 0.125

0.25

0.751.0

0.125 + 0.125 + 0.8430.25 + 0.125

0.25

0.75+ 1.00.125 + 0.125 + 0.843

0.25 + 0.1250.25

0.75+1.00.125 + 0.063 + 0.843

0.25 + 0.1250.25

PREflag

2-leaf3-leaf5-leaf

PRE 7flag

2-leaf3-leaf5-leaf

PRE 10flag

2-leaf3-leaf5-leaf

PRE 6flag

2-leaf3-leaf5-leaf

PRE 62-leaf3-leaf5-leaf

PRE 52-leaf3-leaf5-leaf

*preemergence (PRE) treatments were applied on April 5, two-leaf (2-leaf) on May 6, three-leaf (3-leaf) on May 14, and five-leaf (5-leaf) on June 2.were harvested on September 16 and 17.

Untreated

lb ai/acre Leaf

7 33 599 382 83 1097

28 676 348 70 1122

31 647 391 64 1132

30 683 370 61 1144

23 582 491 126 1221

28 594 433 67 1122

20 111 181 57 1886

INSECTICIDE TRIALS FOR ONION THRIPS (THRIPS TABACI)CONTROL — 2004



Introduction

During the past 4 years alternative insecticides have demonstrated superiorcontrol of onion thrips when compared to conventional insecticides. Alternativeinsecticides in this trial are azadirachtin and Ecozin®) an extractfrom the neem tree (Azadirachia md/ca, A. Juss.), and spinosad (Success®), abacterial fermentation product. Conventional insecticides are the currentlyregistered products in the synthetic pyrethroid (Warrior®, Mustang®), organo-phosphate (parathion, malathion, Guthion®, Diazinon), and carbamate (Lannate®,Vydate®) classes. Different rates and combinations of these insecticides weretested for efficacy against onion thrips.


A 36.7-ft-wide by 500-ft long block was planted to onion (cv. 'Vaquero',Nunhems, Parma, ID) on March 23, 2004. The onions were planted as 2 doublerows on a 44-inch bed. The double rows were spaced 2 inches apart. Theseeding rate was 137,000 seeds/acre. Lorsban 1 5G® was applied in a 6-inchband over each double row at planting at a rate of 3.7 oz/1 ,000 ft of row for onionmaggot control. Water was applied by furrow irrigation. The plots were 7.3 ft wide(2 beds) by 25 ft long and were replicated 4 times.

There were 14 treatments as outlined in Table 1. Acephate is an older insecticidethat is now manufactured by several companies. It is not currently registered foruse on onions.

Insecticide applications were made with a CO2-pressurized plot sprayer with 4nozzles spaced 19 inches apart. All treatments were made with water as a carrierat 38.9 gal/acre. Thrips counts were made weekly through the growing season bycounting the total number of thrips on 20 plants.

The onion bulbs were harvested by hand on September 10 and graded onOctober 11. The plot area harvested was 20 ft of the center 2 double rows.

71

Treatment differences were compared using ANOVA and least significantdifferences at the 5 percent probability level, LSD (0.05). Means were alsocompared using Duncan's multiple range test.


Thrips populations in June were fairly high (Fig.1). The acephate treatmentsprovided the best thrips control. Table 2 contains yield and grade information. Allof the yield classes had significant differences except for medium-size onions.Acephate treatments had the highest yield of supercolossal plus colossal bulbs atboth the 8.0-oz and 16.0-oz rate, and the 6.0 oz rate had the highest yield ofcolossal bulbs. The Aza Direct plus Success (10.0 oz) had the overall highestyield followed by treatment 13, which was a combination of Penncap M plusMSR® and Warrior plus MSR. Acephate at the 6.0-oz rate also produced highyields.

Aza-Direct by itself produced the lowest yields, followed by the late June andmid-July applications of Warrior plus MSR and Warrior plus Lannate (treatment2). Compost tea by itself was not better than the untreated check. Aza-Direct plusthe 6.0-oz rate of Success was not better than the untreated check, whetherapplied as a weekly spray mix or alternated weekly.

The iris yellow spot virus infected the plot area late in the season. The treatmentswere evaluated for resistance to disease expression and the data are shown inTable 3. Generally, the treatments with the highest yields had less incidence ofthe disease although the correlation was not very strong.

Conclusions

Azadirect(20 oz) plus Success applied at the 10.0-oz rate (treatment 14) andacephate at the 8.0-oz rate (treatment 12) were the best treatments. NeitherSuccess or acephate is currently registered for use on onions although a section18 emergency registration for Success was granted in 2004 and is anticipatedagain in 2005.

There were significant differences between treatments in all onion size classesexcept mediums.

72

Table 1. Insecticides evaluated for thrips control, Maiheur Experiment Station,Oregon State University, Ontario, OR, 2004.

Treatment Insecticide applied Formulated product Treatment dateno.

Rate/acre 6/7 6/28 7/16 7/291 Aza-Direct 20.Ooz X X X X

Warrior+ 3.8oz

2 Warrior + 3.8 ozLannate 3.0 pt X

3 Untreated check4 Aza-Direct 20.0 oz X X

Success 6.Ooz X X5 Compost Tea 4.0 gal X X X X6 Warrior 3.8 oz X

Warrior + 3.8 ozLannate 3.0 pt X

7 Aza-Direct + 20.0 ozSuccess 6.Ooz X X X X

8 Acephate 16.Ooz X X X X9 Success 6.Ooz X X

10 Success 6.Ooz X X X X11 Warrior 3.8oz X

Warrior ÷ 3.8 oz

Warrior + 3.8 ozLannate 3.0 pt X

12 Acephate 8.Ooz X X X X13 PenncapM+ 2.0 pt

Warrior + 3.8 ozMSR 2.Opt X

14 Aza-Direct + 20.0 ozSuccess 10.Ooz X X X X

73

Table 2. Effects of different thrips treatments on onion yield and grade, MalheurExperiment Station, Oregon State University, Ontario, OR, 2004.

TreatmentNo.

Medium Jumbo Colossal Super- Colossal Jumbo + Ccl. Totalcolossal + 5-Col. + S-Col. Yield

cwt/acre1 18.2 464.2 220.2 10.7 230.9 695.1 713.32 13.2 394.0 278.9 39.4 318.3 712.3 725.53 11.5 475.3 241.9 44.2 286.1 761.4 773.04 12.4 399.8 322.1 43.7 365.8 765.6 778.05 9.9 501.5 263.3 36.4 299.7 801.2 811.16 13.0 432.0 318.9 50.7 369.6 801.6 814.67 7.4 351.0 351.1 107.3 458.5 809.5 816.98 7.7 296.5 379.3 160.0 539.2 835.7 843.49 13.3 435.8 346.2 87.2 433.3 869.1 882.410 13.2 388.8 398.9 89.6 488.4 877.2 890.311 11.0 398.0 411.4 85.9 497.2 895.2 906.312 6.2 260.0 489.2 165.2 654.4 914.4 920.613 14.1 486.3 382.3 42.4 424.7 911.1 925.214 13.3 431.4 392.5 105.6 498.1 929.6 942.9

LSD ns 133.6 110.8 65.7 142.0 133.6 132.1(0.05)

74

Table 3. Evaluation of iris yellow spot virus disease severity with differentinsecticide treatments for the thrips vector, Malheur Experiment Station, OregonState University, Ontario, OR, 2004.

Treatment Iris yehow spot virus severityNumber

1

0 = dead; 5 =2.8

no injury

2 2.03 2.34 2.35 2.36 2.37 4.08 4.09 2.8

10 3.811 3.212 4.013 3.014 3.8

LSD (0.05) 0.6

75

a30

a-b25-

d-e c-e d-e b-e c-e1d-e

e d-e15

10- -- -- ---a)> - — -—

0- 1234567891011121314Treatment no.

Figure 1. Treatment effects on thrips populations during June, MalheurExperiment Station, Oregon State University, Ontario, OR, 2004.

76

A TWO-YEAR STUDY ON VARIETAL RESPONSE TO AN ALTERNATIVEAPPROACH FOR CONTROLLING ONION THRIPS (THRIPS TABACI) IN

SPANISH ONIONS


Clinton Shock and Lamont SaundersMalheur Experiment Station

Oregon State UniversityOntario, OR, 2003-2004

Introduction

Onion (A/hum cepa L.) is a major economic crop in the Treasure Valley of easternOregon and western Idaho. Annually about 20,000 acres of onion are grown in thevalley. Typically Spanish hybrids are grown for their large size, high yield, and mildflavor.

The principal onion pest in this region is onion thrips (Thrips tabaci, Lindeman). Thripscause yield reduction by feeding on the epidermal cells of the plant. Onion thrips canreduce total yields from 4 to 27 percent, depending on the onion variety, but can reduceyields of colossal-sized bulbs from 27 to 73 percent. The larger sized colossal bulbs aredifficult to grow and demand a premium in the marketplace. Growers typically spraythree to six times per season to control onion thrips. Treatments include the use ofsynthetic pyrethroid, organophosphate, and carbamate insecticides. The ability of theseproducts to control thrips has decreased from over 90 percent control in 1995 to lessthan 70 percent control in 2000. Onion growers are applying insecticides morefrequently in order to keep thrips populations low.

New biological insecticides with low toxicity to beneficial predators have beendeveloped, including neem tree (Azadirachta md/ca A. Juss.) extracts (azadirachtin) andbacterial fermentation products (spinosad). Both of these materials have previouslybeen evaluated for thrips control and have performed poorly compared to conventionalinsecticides. Studies during the past 2 years have shown that applications of spinosadand azadirachtin coupled with straw mulch are superior to conventional insecticideprograms for controlling onion thrips in 'Vaquero' onions. Vaquero was used in the studybecause of its vigorous growth characteristics and resistance to thrips injury comparedto slower growing varieties. The objective of this study was to test this program onvarieties that are highly susceptible to thrips injury.


A 1.5-acre field was planted to the onion varieties Vaquero, 'Flamenco', and 'Redwing'(cv. Vaquero, Flamenco, Nunhems, Parma, ID; Redwing, Bejo Seeds, Oceano, CA) in a

77

split plot design on March 14, 2003 and March 23, 2004. Vaquero is a yellow varietywhile Redwing and Flamenco are red varieties. Red varieties are generally assumed tobe more attractive to thrips than yellow varieties. The onion varieties were planted as 2double rows on a 44-inch bed. The double rows were spaced 2 inches apart. Theseeding rate was 137,000 seeds/acre. Lorsban 15G® was applied in a 6-inch band overeach row at planting at a rate of 3.7 oz/1 000 ft of row for onion maggot control. Waterwas applied by furrow irrigation. The field was divided into plots 37 ft wide by 100 ftlong. There were three treatments with six replications.

The three treatments were a grower standard treatment, an untreated check, and thealternative treatment as described previously (Jensen et al. 2003a, 2003b). The growerstandard treatment included Warrior® (lambda-cyhalothrin), MSR® (oxydemeton-methyl),and Lannate® (methomyl). The untreated check did not receive any treatments for thripscontrol. The alternative treatment included straw mulch applied to the center of the bedplus Success® (spinosad), and (azadirachtin).

Insecticide treatments were applied 7-10 days apart during the growing season (Table1). All insecticides were sprayed in water at 31 gal/acre in 2003 and 39 gal/acre in 2004.Straw was applied only between the irrigation furrows on top of the beds to avoidconfounding irrigation effects with thrips effects. The straw was applied on May 1, 2003at a rate of 1,080 lb/acre. Straw was not applied in 2004 because results in 2003suggested it was not enhancing thrips control.

Thrips populations were sampled by two methods. The first was by visually counting thenumber of thrips on 20 plants. The second method was by cutting 10 plants at groundlevel and inserting the plants into a berlese funnel. Turpentine used in the berlesefunnel dislodged the thrips from the plant into a jar containing 90 percent isopropylalcohol. The collected thrips were then counted through a binocular microscope. Thripspopulations were monitored weekly through the growing season.

The predator populations were monitored using pitfall traps that contained ethyleneglycol. They were evaluated three times per week. The berlese funnel was also used tomonitor predators foraging on the plants. The onions were harvested in September andgraded in October of each year.

Treatment differences were compared using ANOVA and least significant differences atthe 5 percent probability level, LSD (0.05). Means were also compared using Duncan'smultiple range test.


Weekly thrips populations are compared in Figure 1. The alternative program had asignificantly lower average thrips population than the untreated check in both years (Fig.2). Visual damage to the foliage was observed with the variety Vaquero in 2004 but notin 2003. Flamenco showed severe foliage damage from thrips feeding. The visual thrips

78

damage to Redwing appeared intermediate between Vaquero and Flamenco. Flamencois less vigorous than Redwing and more thrips damage would be expected.

There were no yield differences between any of the treatments with Vaquero in 2003but the alternative treatment produced significantly more colossal- and super-colossal-sized bulbs in 2004 (Table 2).

Redwing significantly increased yield of colossal-sized bulbs with the alternativetreatment both years compared to both the standard and untreated check andsignificantly increased in total yield in 2003 compared to the untreated check (Table 3).

Flamenco responded to the alternative treatments with significantly less medium-sizeyield and higher jumbo and colossal yield compared to the untreated check in 2003(Table 4). There was a trend towards higher total yield and larger bulb size compared tothe standard treatment but this was only significant in the colossal size class in 2003.The alternative plus standard treatments produced higher total yields than the untreatedcontrol in 2004.

Predator populations (Fig. 3) were significantly higher in the alternative and untreatedcheck treatments than in the standard treatment. The predator population consistedmostly of spiders, big-eyed bugs, minute pirate bugs, damsel bugs, lacewings and ladybird beetles.

The 2004 season experienced an epidemic of iris yellow spot virus (IYSV) in the trialarea and surrounding fields. The IYSV is a new disease currently spreading to mostproduction areas of the United States and the world. Onion thrips are the vector, so thistrial gave the opportunity to evaluate the alternative program for IYSV control (Table 5).The treatments grown under the alternative treatment were healthier and showedsignificantly less virus damage than the standard insecticide treatment or the untreatedcheck.

Red onions often exhibit thrips scarring when placed in storage due to continuedfeeding by the insects. The alternative treatment produced significantly fewer damagedbulbs compared to the untreated check with the Redwing variety, and a similar thoughnot significant trend with Flamenco (Table 6). Averaged over treatment, Redwing hadless thrips injury than Flamenco.

Conclusion

The alternative treatments were equal to or in some cases significantly better than thestandard insecticide program. There was a general trend towards higher yields in thelarger bulb classes, which gives a higher return to the grower. The alternative programproduced less thrips damage to red onions in storage and reduced the incidence of irisyellow spot virus.

79

References

Jensen, L., B. Simko, C. Shock, and L. Saunders 2002. Alternative methods forcontrofling onion thrips (Thrips tabaci) in Spanish onions. Pages 65-72 in Proceedingsof the 2002 AIlium Research National Conference.

Jensen, L., B. Simko, C. Shock and L. Saunders. 2003. Alternative methods forcontrolling thrips. Pages 895-900 in British Crop Protection Council: Crop Science andTechnology 2003 Congress Proceedings. Vol. 2.

Jensen, L., B. Simko, C. Shock, and L. Saunders 2003a. Alternative methods forcontrolling onion thrips (Thrips tabaci) in Spanish onions. Proceedings of the 2003Idaho-Maiheur County Onion Growers Annual Meeting Feb. 2003. 7 pages.

Jensen, L., C. Shock, B. Simko, and L. Saunders 2003b. Straw mulch and insecticide tocontrol onion thrips (Thrips tabaci) in dry bulb onions. Pages 19-30 in Proceedings ofthe Pacific Northwest Vegetable Association 17th Annual Meeting.

80

Table 1. Application dates for thrips control on two red and one yellow onion variety,Malheur Experiment Station, Oregon State University, Ontario, OR, 2003-2004.

Standard insecticide treatment Alternative insecticide treatmentApplication date Insecticides applied Rate/acre Insecticides applied Rate/acre

2003June 7 Warrior 3.84 oz. Aza-Direct 20.0 oz.

Success 10.Ooz.June14 Aza-Direct 20.Ooz.

Success 10.Ooz.June 25 Warrior 3.84 oz.

Lannate 3.Ooz.July 3 Aza-Direct 20.0 oz.

Success 10.Ooz.July 7 Warrior 3.84 oz.

MSR 2.0 pt.July11 Aza-Direct 20.Ooz.

Success 10.OozJuly 25 Warrior 3.84 oz.

Lannate 3.0 pt.July 29 Aza-Direct 20.0 oz

Success 10.Ooz.

2004June 6 Warrior 3.84 oz. Aza-Direct 20.0 oz.

MSR 2.0 pt. Success 10.0 oz.June 16 Warrior 3.84 oz. Aza-Direct 20.0 oz.

MSR 2.0 pt. Success 10.Ooz.June 23 Warrior 3.84 oz. Aza-Direct 20.0 oz.

Lannate 3.0 pt. Success 10.0 oz.July 1 Warrior 3.84 oz. Aza-Direct 20.0 oz.

Lannate 3.0 pt. Success 1O.Ooz.July 8 Warrior 3.84 oz. Aza-Direct 20.0 oz.

MSR 2.0 pt. Success 10.Ooz.July 19 Warrior 3.84 oz. Aza-Direct 20.0 oz.

Lannate 3.0 pt. Success 10.Ooz.July 29 Warrior 3.84 oz. Aza-Direct 20.0 oz.

Mustang 4.0 oz. Success 10.Ooz.Lannate 3.0 pt.

81

Table 2. Yield and grade of Vaquero onion with different strategies for controlling onionthrips, Maiheur Experiment Station, Oregon State University, Ontario, OR.

2003

Treatment Medium Jumbo ColossalSuper-

colossalTotalyield

Untreatedcwt/acre

check 9.7 459.7 464.1 124.0 1057.5Standard 9.8 451.0 489.6 140.9 1091.3Alternative 10.9 446.1 484.2 145.2 1086.4LSD (0.05) ns ns ns ns ns

2004


colossalTotalyield

Untreatedcwt/acre

check 17.6 586.1 254.5 29.8 888.0Standard 11.9 511.3 306.9 52.3 882.4Alternative 14.8 409.3 377.4 126.9 928.4LSD (0.05) ns ns 76.9 71.9 ns

82

Table 3. Yield and grade of Redwing onion with different strategies for controlling onionthrips, Maiheur Experiment Station, Oregon State University, Ontario, OR.

2003


colossalTotalyield

Untreatedcwt/acre

check 12.0 726.4 107.4 4.0 849.8Standard 14.2 724.2 174.3 2.2 914.9Alternative 11.6 701.2 240.2 6.9 959.9LSD (0.05) ns ns 62.2

2004

ns 56.3

Treatment Medium Jumbo ColossalSuper-colossal

Totalyield

Untreatedcwt/acre

check 57.6 395.1 9.1 0 461.8Standard 50.8 509.0 15.4 0 575.2Alternative 52.1 445.6 36.9 0 534.6LSD (0.05) ns ns 16.5 ns ns

83

Table 4. Yield and grade of Flamenco onions with different strategies for controllingonion thrips, Malheur Experiment Station, Oregon State University, Ontario, OR.

2003Total

Treatments Medium Jumbo Colossal yield

Untreatedcwt/acre

check 121.5 380.5 1.0 512.4Standard 107.1 442.3 9.2 565.5Alternative 94.0 486.1 19.1 606.9LSD (0.05) 16.9 55.5 7.8

2004

51.8

Treatments Medium Jumbo ColossalTotalyield

Untreatedcwtlacre

check 128.1 175.1 0.3 512.4Standard 101.0 275.3 1.0 565.5Alternative 82.2 305.9 10.7 606.9LSD (0.05) ns ns ns 51.8

Table 5. Average iris yellow spot virus injury for insecticide treatments, MaiheurExperiment Station, Oregon State University, Ontario, OR, 2004.

Treatment IYSV*

Untreated 1.5

Standard 1.7

Alternative 2.2

LSD (0.05)*Scale: 0 = dead, 5 = healthy,

0.4no lesions.

84

Table 6. Thrips injury on two stored red onion varieties, Maiheur Experiment Station,Oregon State University, Ontario, OR, 2003.

Thrips injuryTreatment Redwing Flamenco

(0 = no injury, 10 = severe injury)Alternative 1 1 .3

Standard 1.3 1.6Untreated check

LSD (0.05)

Varietal

1.50.3

differences

2.1ns

Redwing 1.27Flamenco

LSD (0.05)1.680.39

85

U)a.I..

-C

th>

25

20

15

10

5

0

13-Jun 24-Jun 30-Jun 9-Jul 23-Jul 31-Jul 7-Aug

—.-— Untreated check —u—Standard —a—Alternative

14-Aug

2003

2004

25

a.

U) 15a-I-

-C

110

0I I

8-Jun 15-Jun 22-Jun 29-Jun 6-Jul 13-Jul 20-Jul 27-Jul 3-Aug 10-Aug

—.-— Standard —i-— Untreated

Figure 1. Thrips populations with different treatments in an alternative thrips controlprogram, Maiheur Experiment Station, Oregon State University, Ontario, OR.

86

I

2003

4-.

C-I-.z

4C)>

2

0Untreated check Standard Alternative

2004

7

6

5

5. 4

Cl)C. 3

.c2

C)

1

0

Untreated Standard Alternative

Figure 2. Average season-long thrips populations in an alternative thrips controlprogram, Malheur Experiment Station, Oregon State University, Ontario, OR.

87

001

2 25

200

Untreated check Standard Alternative

Figure 3. Predator populations in the alternative thrips trial, Maiheur Experiment Station,Oregon State University, Ontario, OR, 2003.

88

A ONE-YEAR STUDY ON THE EFFECTIVENESS OF OXAMYL(VYDATE L®) TO CONTROL THRIPS IN ONIONS WHEN INJECTED INTO A

DRIP-IRRIGATION SYSTEM

Lynn JensenMaiheur County Extension Office

Eric Feibert, Clint Shock, and Lamont SaundersMalheur Experiment Station


Introduction

Onion thrips and western flower thrips are the main insect pests on onions grown in theTreasure Valley of Idaho and eastern Oregon. In this region about 3,000 acres of onionsare grown under drip irrigation. Because of the increased yield and quality of onionsgrown under drip irrigation, this management practice is increasing on lands that wereformerly marginal for onion production. It is a common practice to inject the systemicinsecticide oxamyl (Vydate L®) into the drip lines on a weekly or biweekly basis tocontrol thrips. Most growers also apply two to six foliar insecticide applications inaddition to the oxamyl applications. Growers using conventional furrow irrigationcommonly use four to six foliar insecticide applications for thrips control. The dripirrigation growers feel there is an economic advantage to the additional oxamylapplications even though the additional cost is about $150/acre. This trial was designedto determine the effectiveness of oxamyl at two different application rates and incombination with two foliar insecticide programs.


The trial was conducted at the Malheur Experiment Station on an Owyhee silt loam soilpreviously planted to wheat. Onion (cv: 'Vaquero'; Nunhems, Parma, ID) was planted onMarch 23 in 2 double rows on a 44-inch bed. The double rows were spaced 2 inchesapart. The seeding rate was 150,000 seeds/acre. Lorsban 1 5G® was applied in a 6-inchband over each double row at a rate of 3.7oz/1 ,000 ft of row for maggot control. Thedrip tape was placed in the center of the bed between the double rows. The drip tape(T-tape, T-Systems International, Inc., San Diego, CA) had a flow rate of 0.22gal/mm/i 00 ft of tape. Irrigation water was applied when the soil water potential reached—20 kPA. Water potential was determined by granular matrix sensors (GMS, WatermarkSoil Moisture Sensors Model 200ss, Irrometer Co. Inc., Riverside, CA) installed at 8-inch depth in the center of the double row.

The experimental design was a randomized complete block design with fourreplications. The plot size was 8 double rows wide (37.5 ft) by 34 ft in length.

89

Oxamyl was injected into the main irrigation line by a positive displacement injector(Dosmatic Model A30, Dosmatic USA, Inc., Carollton, TX). Prior to injecting oxamyl, 95percent sulfuric acid was diluted at a ratio of 1:6,248 acid to water to buffer the water inthe soil solution to a pH of 5.0. The oxamyl was added to water buffered at the sameratio and injected immediately after the initial buffer treatment. The buffered water andbuffered oxamyl treatments required 20 minutes each to inject into the treated plots.This process applied slightly more water to the treated plots compared to the untreated,but the additional water was minor compared to the overall applied water and probablydid not have an overall impact on the final yield.

Each plot had four drip tapes supplying water to the eight double rows. Each plot wasequipped with an on/off valve so that oxamyl could be applied to individual plots asneeded. There were 6 treatments including an untreated check, a standard insecticideprogram, oxamyl at 1.0 qt/acre applied weekly, oxamyl at 2.0 qt/acre applied everyother week, oxamyl at 1.0 qt/acre plus a standard insecticide program and oxamyl at 1.0qt/acre plus the bio-insecticides azadirachtin and spinosad (Success®)(alternative program). Azadirachtin and spinosad have shown promise underconventional systems by suppressing thrips and allowing predatory insect populationsto build to the point where they control thrips. Systemically applied through the dripsystem, oxamyl has the potential to enhance this program. The application dates of thetreatments are shown in Tables 1 and 2.

Thrips counts were made weekly by counting the total number of thrips on 15 plants ineach plot. Onions were harvested on September 9 and 10 and graded on October 5. Avisual evaluation for iris yellow spot virus was taken on August 19.

Treatment differences were compared using ANOVA and least significant differences atthe 5 percent probability level, LSD (0.05).


Figure 1 shows the weekly thrips populations found in the different treatmentsthroughout the growing season. There was a tendency for the oxamyl plus alternativetreatments to have lower thrips pressure than the other treatments. The season averagethrips populations are shown in Table 3. The oxamyl at 1.0 qt every week plus thealternative bio-insecticides had significantly lower total thrips populations than the othertreatments. There were no significant differences in thrips populations between theother treatments, including the untreated check.

Table 4 shows the breakdown in yield and quality between the different treatments.There was a significant increase in colossal-sized bulbs with the three foliar-appliedinsecticide treatments versus the untreated check or the oxamyl alone treatments.

Iris yellow spot virus (IYSV), which is thrips transmitted, appeared in the trial duringAugust. A visual evaluation of the onions for IYSV showed significantly less infection in

90

the oxamyl plus azadirachtin plus spinosad treatment compared to the oxamyl alonetreatments or the untreated check (Table 5).

Conclusion

The oxamyl plus alternative insecticides (azadirachtin plus spinosad) treatmentsignificantly controlled thrips better than any other treatment and had the highest yieldof colossal, super-colossal, and total yield. All of the treatments with foliar insecticidesgave significantly higher colossal yields compared to the oxamyl only and the untreatedcheck. Oxamyl treatments applied as 1.0 qt/acre weekly or 2.0 qt/acre every other weekwere no better than the untreated check. The lack of thrips control by oxamyl may bedue to the late initial application on June 3. This application was about 2 weeks laterthan growers would typically start. There was also the possibility that the oxamyl wasnot applied with enough irrigation water to allow movement to the onion roots during theearly onion growth period when the root zone was small.

Table 1. Application dates for the different treatments in the drip-irrigation/oxamyl trial,Maiheur Experiment Station, Oreqon State University, Ontario, OR, 2004.

Date Oxamyl 1.0 qt/wkOxamyl 2.0 qt every

other weekStandardinsecticide

Alternativeinsecticide

6/03 X X6/04 X X6/11 X X6/16 X X X6/23 X X6/25 X7/02 X X X X7/08 X X X7/19 X7/20 X X7/29 X X8/06 X

91

Table 2. Application dates for foliar insecticide applications for thrips control on drip-irrigated onions, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Product Rate/acre Product Rate/acreJune 6 Warrior

MSR3.84 oz.2.0 pt.

Aza-DirectSuccess

20.0 oz.10.0 oz.

June 16 WarriorMSR

3.84 oz.2.0 pt.

Aza-DirectSuccess

20.0 oz.10.0 oz.

June 23 WarriorLannate

3.84 oz.3.0 pt.

Aza-DirectSuccess

20.0 oz.10.0 oz.

July 1 WarriorLannate

3.84 oz.3.0 pt.

Aza-DirectSuccess

20.0 oz.10.Ooz.

July 8 WarriorMSR

3.84 oz.2.0 pt.

Aza-DirectSuccess

20.0 oz.10.0 oz.

July 19 WarriorLannate

3.84 oz.3.0 pt.

Aza-DirectSuccess

20.0 oz.10.Ooz.

July 29 WarriorMustangLannate

3.84 oz.4.0 oz.3.0 pt.

Aza-DirectSuccess

20.0 oz.10.0 oz.

Table 3. Average thrips counts for the 2004 season,State University, Ontario, OR, 2004

Malheur Experiment Station, Oregon

Treatment - Average thrips/plantUntreated 47.9oxamyl 2.0 qt - every other week 51.8oxamyl 1.0 qt - every week 50.7oxamyl 1.0 qt + alternative 36.2oxamyl 1.0 qt + standard 49.6Standard treatment 50.1

LSD (0.05) 9.6

Table 4. Total yield of oxamyl-treated onions grown under drip irrigation, MalheurExperiment Station, Oregon State University, Ontario, OR, 2004.

Onion Yield

Super-Medium Jumbo Colossal colossal Total yield

Treatmentcwtf acre

26.4 676.3 198.3 11.9 912.9Untreated

oxamyl 2.0 qt (every other week) 30.4 642.3 210.8 22.8 906.3oxamyl 1.0 qt (every Week) 22.8 708.1 193.5 13.3 937.7oxamyl 1.0 + Alternative 19.6 630.5 326.4 46.1 1022.6oxamyl 1.0 + Standard 17.4 633.7 307.4 34.7 993.2Standard only 21.3 655.6 310.9 28.0 1015.8

LSD (0.05) ns ns 91.3 ns ns

92

Table 5. Iris yellow spot virus (IYSV) eirrigation, Maiheur Experiment Station,

valuation in oxamyl-treated onionsOregon State University, Ontario,

grown under dripOR, 2004.

Treatment IYSV rating 1 = no virus, 5 = severe virusUntreated 3

oxamyl 2.0 qt (every other week) 3oxamyl 1.0 qt (every Week) 3.3oxamyl 1.0 + Alternative 1.8oxamyl 1.0 + Standard 2.5Standard only 2.5

LSD (0.05) 0.9

0 0 0 0o o 0 0co

(N (NS.-(0 (0 (0

o 0 0 0o 0 0 CD

(0 (N C) (0r (NS.-N- N- N-

o oo 0

co co

Figure 1. Weekly thrips populations, 2004 oxamyl/drip trial,Oregon State University, Ontario, OR, 2004.

93

Malheur Experiment Station,

I

C

S.-

U)

ci>

18

16

14

12

10

8

6

4

2

0

L

—-.-— Untreated

• Vydate2.0

—-*-— Vydate 1.0

Vydate + Alt

- Vydate+St.• Standard

GROWERS USE LESS NITROGEN FERTILIZER ON DRIP-IRRIGATEDONION THAN FURROW-IRRIGATED ONION

Jim Klauzer and Clinton ShockMalheur Experiment Station

Oregon State University and Clearwater SupplyOntario, OR, 2004

Sum mary

Over previous years, research at the Malheur Experiment Station has shown thatnitrogen (N) needs of drip-irrigated onion can be modest (Shock et al. 2004). In 2002,surveys of two growers' furrow-irrigated and drip-irrigated onion fields showed that Nfertilizer use efficiency was substantially better in drip-irrigated fields than infurrow-irrigated fields (Shock and Klauzer 2003). In 2004 we repeated this survey withvarious growers' fields.

Introduction

Drip irrigation is generally used on fields with imperfect topography, lower soil fertility,and histories of lower productivity compared to the fields used for furrow irrigation.From 1992 to 1994 we demonstrated that drip irrigation is an effective irrigation practicecompared to furrow and sprinkler irrigation for onion production on Treasure Valley soilsthat were difficult to irrigate (Feibert et al. 1995). While 320 lb N/acre is commonlyused in furrow-irrigated onion production, drip-irrigated onion is not very responsive to Nfertilizer (Shock et al. 2004). The lower response of drip-irrigated onion could bebecause less irrigation water is applied using drip. With less irrigation, water is less aptto leach away residual soil nitrate and N from mineralization, allowing these N sourcesto supply the crop much of its N needs. Here we report growers' 2004 nitrogen fertiliza-tion practices using drip- and furrow-irrigation systems and the corresponding cropyields.


Growers were asked to keep records of all fertilizer and water supplied to their onionfields. Yield was recorded for each field. The soil water potential was monitored inselected fields. The bulb yield was recorded. This report covers the yield, N applied,and yield per unit of applied N fertilizer for onions grown using drip and furrow irrigation.Some of the drip-irrigated fields were of poorer soil quality than the correspondingfurrow-irrigated fields.

Although root tissue testing for nitrate is a proven method to assure adequate suppliesof N for onion, to improve yields, and save on N fertilizer costs, none of the growerssurveyed conducted root tissue testing.

94


For the growers and fields surveyed in 2004, growers applied on average 279 lb N/acrewhen growing onions with furrow irrigation, while only 173 lb N/acre was applied withdrip irrigation (Table 1). These N rates include all N applied during the fall prior to thecrop year, spring preplant fertilizer, sidedressed N, and N applied by fertigation in theirrigation water.

Drip irrigation out-yielded furrow irrigation by an average of 68 cwt/acre for 4 growersand furrow irrigation out-yielded drip by 300 cwt/acre for 1 grower (Table 1). The lowyielding drip-irrigated onion was from a very unfavorable field. The 2004 TreasureValley growing season was favorable for high onion yields and excellent onion quality.During previous years, with more heat and water stress potential, larger yielddifferences were observed in favor of drip irrigation.

As a consequence of lower N fertilizer rates used for drip-irrigated onions than forfurrow-irrigated onion, more onions were produced for each pound of applied N usingdrip (Table 1). The surveyed growers might have economized further on N fertilizercosts through root tissue testing for nitrate. Thorough nutrient management for onionhas been described by Sullivan et al. (2001) and the methods they discuss areunderutilized.

Growers used less N fertilizer under drip irrigation and yields were on average similar tofurrow irrigation even though the soils in a few cases had less favorable physical andchemical properties. Under furrow irrigation, much more water is applied at eachirrigation. The potential for deep leaching of nitrate and groundwater contamination issubstantial with furrow irrigation. With drip irrigation it is easier to maintain uniform soilmoisture, even on difficult sites. Since each water application with a drip system can becarefully managed to just replace water used by the crop, nitrate leaching can begreatly reduced with drip irrigation, and this results in better N fertilizer use at acommercial scale.

Drip irrigation may provide an important option for growers who wish to rotate oniononto soils not usually used for the crop. These fields may not be as highly infested withpathogens from short rotations of cash crops.

References

Feibert, E.G.B., C.C. Shock, and L.D. Saunders. 1995. A comparison of sprinkler,subsurface drip, and furrow irrigation of onions. Oregon State University AgriculturalExperiment Station, Special Report 947:59-67.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2004. Plant population and nitrogenfertilization for subsurface drip-irrigated onion. HortScience 39(7):1722-1 727.

95

Shock, CC., and J. Klauzer. 2003. Growers conserve nitrogen fertilizer on drip-irrigatedonion. Oregon State University Agricultural Experiment Station, Special Report1048:61-63. http://www.cropinfo.net/AnnualReports/2002/OnionDripNitrogeno2.htm

Sullivan, D.M., B.D. Brown, C.C. Shock, D.A. Horneck, R.G. Stevens, G.Q. Pelter, andE.B.G. Feibert. 2001. Nutrient management for sweet Spanish onions in the PacificNorthwest. Oregon State University. Pacific Northwest Extension Publication PNW 546.26 pages.

Table 1. Comparison of nitrogen (N) fertilizer rates, onion yield, and bulb yield perpound of applied N in furrow-irrigated and drip-irrigated onion, Treasure Valley ofOregon and Idaho, 2004.

Grower Average1 2 3 4 5

Furrow irrigationN rate, lb/acre 250 320 275 250 300 279Yield, cwt/acre 810 800 855 750 850 813*Ratio, cwt/lb N 3.24 2.5 3.11 3 2.83 2.94

Drip irrigationN rate, lb/acre 140 175 150 230 172 173Yield, cwt/acre 860 850 930 850 550t 808*Ratio,cwt/lbN 6.14 4.86

onion is grown on6.2

soil that is I

3.7ess favorab

3.2le than

4.82furrow-irrigated*Often drip-irrigated

onion.tExtremely unfavorable soil.

96

PERFORMANCE OF HYBRID POPLAR CLONES ON AN ALKALINE SOIL

Clinton Shock and Erik FeibertMalheur Experiment Station


Introduction

With timber supplies from Pacific Northwest public lands becoming less available,sawmills and timber products companies are searching for alternatives. Hybrid poplarwood has proven to have desirable characteristics for many nonstructural timberproducts. Plantings of hybrid poplar for sawlogs have increased in the Treasure Valley.

Many hybrid poplar clones are susceptible to nutrient deficiencies in alkaline soils,leading to chlorosis, poor growth, and eventual death of trees. Poor growth on alkalinesoil can be partly a result of iron deficiency caused by the low solubility of ironcompounds in alkaline soil. A symptom of iron deficiency is yellow leaves or"chiorosis". Chlorosis can also be caused by other nutrient problems.

Previous clone trials planted in 1995 in Malheur County demonstrated that cloneOP-367 (hybrid of Populus deltoides x P. nigra) was the only clone performing well onalkaline soils at that time. Growers in Malheur County have made experimentalplantings of hybrid poplars and found that other clones have higher productivity on soilswith nearly neutral pH. New poplar clones are continually being developed. Thecurrent trial seeks to provide poplar growers with updated information on the relativevigor and adaptability of a larger number of clones on alkaline soils.


2003 ProceduresThe trial was conducted on Nyssa silt loam with 1.3 percent organic matter and a pHranging from 7.7 at the field top to 8.4 at the field bottom. The field had been planted towheat in the fall of 2002. On March 28, 2003, the wheat was sprayed with Roundup®(Glyphosate) at 1.5 lb ai/acre. Based on a soil analysis, on April 9, 2003, 20 lbmagnesium (Mg), 40 lb potassium (K), 1 lb boron (B), and 1 lb copper (Cu) per acrewere broadcast. The field was again sprayed with Roundup at 1.5 lb ai/acre on April 9.On April 10, 9-inch poplar sticks of 24 clones (Table 1) were planted in a randomizedcomplete block design with 5 replicates. Three of the clones were designated Malheur1, 2, and 3 corresponding to three selections of eastern cottonwood (Populus deltoides)found growing in Malheur County. Tree rows were spaced 5 ft apart and trees werespaced 5 ft apart within the rows. Each plot consisted of four trees two rows wide andtwo trees long. Goal® herbicide (Oxyfluorfen) at 2 lb ai/acre was applied on April 11.The field was irrigated with 0.6 inch of water on April 11.

97

Drip tubing (Netafim Irrigation, Inc., Fresno, CA) was laid along the tree rows prior toplanting. The drip tubing had two emitters (Netafim On-line button dripper) spaced 12inches apart for each tree. Each emitter had a flow rate of 0.5 gal/hour. The field wasirrigated when the soil water potential at 8-inch depth reached -25 kPa. Each irrigationapplied 0.6 inch of water based on an 8-ft2 area for each tree. This irrigation strategywas able to maintain the soil water potential above -25 kPa until around mid-July.Starting around mid-July the irrigation rate was increased to 1 inch per irrigation. Thisincreased irrigation rate did not maintain the soil water potential above -25 kPa due toinadequate irrigation frequency, so starting in mid-August the field was irrigated 5-7times per week until the last irrigation on September 30. Soil water potential wasmeasured with six Watermark soil moisture sensors (model 200SS, Irrometer Inc.,Riverside, CA) installed at 8-inch depth. The soil moisture sensors are read every 8hours by a Hansen Unit datalogger (Mike Hansen Co., Wenatchee, WA).

Analysis of leaf samples (first fully expanded leaf from clone OP-367) taken on July 11showed unexpected needs for boron and sulfur fertilization (Table 1). On July 28, sulfurat 10 lb/acre as ammonium sulfate and B at 0.2 lb/acre as boric acid were injectedthrough the drip system.

2004 ProceduresOn March 25, 2004, Casoron 4G® at 4 lb ai/acre was broadcast for weed control.Based on a soil analysis, nitrogen (N) at 80 lb/acre, Cu at 1 lb/acre, and B at 1 lb/acrewere injected through the drip tape on May 10. Analysis of leaf samples (first fullyexpanded leaf from clone OP-367) on July 8 showed the need for B (Table 1). On July19, B at 0.2 lb/acre was injected through the drip system. On August 20, a soil sampleconsisting of 20 cores was taken from each replicate and analyzed for pH.

On August 10, leaf chlorophyll content was measured on two leaves per tree using aMinolta SPAD 502 DL meter (Konica Minolta Photo Imaging U.S.A., Inc., Mahwah, NJ).On August 20, trees in all plots were evaluated subjectively for visual symptoms of leafchlorosis. On September 10 the trees in all plots were evaluated subjectively for stemdefects. The heights and diameter at breast height (DBH, 4.5 ft from ground) of alltrees in each plot were measured in October 2003 and 2004. Stem volumes (cubicfeet, excluding bark and including stump and top) were calculated for each tree usingan equation (stem volume 1 0(2945047+1 .803973*LOG1 O(DBH)+1 .238853*LOG1 O(Hei9ht))) developed for

poplars that uses tree height and DBH (Browne 1962). Clonal differences in height,DBH, and wood volume were compared using ANOVA and least significant differencesat the 5 percent probability level, LSD (0.05). The LSD (0.05) values at the bottom ofTable 2 should be considered when comparisons are made between clones forsignificant differences in performance characteristics. Differences between clonesequal to or greater than the LSD (0.05) value for a characteristic should exist before anyclone is considered different from any other clone in that characteristic. To evaluate thesensitivity of the clones to soil pH, a regression analysis of leaf chlorophyll contentagainst soil pH was run for each clone separately. If the regression analysis had aprobability level of 5 percent or less, the clone was considered to be sensitive to soilpH.

98


Starting around mid-July 2003 and 2004, the soil water potential failed to remain abovethe target of -25 kPa (Fig. 1). A total of 22 and 44 inches of water plus precipitationwere applied during the season to the whole field in 2003 and 2004, respectively (Fig.2). Based on our previous work (Shock et al. 2002), greater tree growth and woodvolume would have been expected if the intended soil water potential could have beenmaintained, which would have required a greater amount of water to be applied.However, water infiltration in this field was restricted; we observed runoff out of thebottom of the field.

Chiorotic leaves were observed on trees in replicates 2, 3, and 4 of the trial. The soil pHwas 7.7, 8.2, 8.4, and 8.4 for replicates 1 to 4, respectively. Relative leaf chlorophyllcontent rankings ranged among clones from 25.8 to 49.3 percent (Table 2). Theregression analysis of soil pH and leaf chlorophyll content showed some clones to beinsensitive to soil pH in terms of leaf chlorophyll content (Table 2). The leaf chlorophyllcontent of the sensitive clones decreased with increasing soil pH. The leaf chlorophyllcontent of the clones insensitive to soil pH (12 clones) averaged 42.4 percent. The leafchlorophyll content of the clones sensitive to soil pH (12 clones) averaged 31.8 percent.There was a linear relationship (R2 = 0.62, P = 0.001) between leaf chlorophyll contentand the visual rating of leaf chlorosis (Fig. 3). The trees insensitive to soil pH averageda subjective visual rating of leaf chlorosis of 0.52 (0 = no visual symptoms of chlorosis,5 = very chlorotic). The trees sensitive to soil pH averaged a visual rating of leafchiorosis of 2.15. The three P. deltoides selections from Malheur County had amongthe darkest green leaves, and leaf sizes were smaller. For the clones sensitive to soilpH, tree growth decreased with increasing severity of leaf chlorosis and with decreasingleaf chlorophyll content (Figs. 4 and 5). For the clones insensitive to soil pH, treegrowth was not related to leaf chlorosis or leaf chlorophyll content.

Subjective rating of stem defects (0 = no defects, 2 = more than half of the trees haveeither split or crooked tops) ranged from 0 defects for clone 57-276 to 1.75 for clone49-177 (Table 1).

Tree height in October 2004 ranged from 13 ft for 50-184 to 22.6 ft for 59-289 (Table 2).Diameter at breast height ranged from 1.45 inches for 311-93 to 2.41 inches for184-401. Stem volume ranged from 119.3 inch3 for 50-184 to 437 inch3 for 59-289.Clones 59-289, Malheur 3, 184-401, and 50-197 were among those with the greateststem volume. Stem volume growth in 2004 ranged from 113.3 inch3 for 50-1 84 to 414.2inch3 for 59-289. Clones 59-289, Malheur 3, 184-401, and 50-197 were among thosewith the greatest stem volume growth in 2004.

Considering all measured characteristics, clones 59-289 and Malheur 3 had among thebest performance over the 2 years of the trial. These two clones had high growth, highleaf chlorophyll content, insensitivity to soil pH, and low incidence of stem defects.Clone 59-289 was taller than OP-367. Compared to OP-367, clones 59-289 andMalheur 3 had greater stem volume, but were similar in leaf chlorophyll content,

99

insensitivity to soil pH, and incidence of stem defects. The choice of clones forcommercial production needs to be made on the basis of wood productivity through anentire growth cycle and ultimately on wood quality, parameters that are currentlyunavailable for 59-289 and Malheur 3.

References

Browne, J.E. 1962. Standard cubic-foot volume tables for the commercial tree speciesof British Columbia. British Columbia Forest Service, Forest Surveys and InventoryDivision, Victoria, B.C.

Shock, C.C., E.B.G. Feibert, M. Seddigh, and L.D. Saunders. 2002. Waterrequirements and growth of irrigated hybrid poplar in a semi-arid environment in easternOregon. Western J. of Applied Forestry 17:46-53.

Table 1. Analysis of hybrid poplar leaf samples (first fully expanded leaf from cloneOP-367), Malheur Experiment Station, Orecion State University, Ontario, OR.

Nutrient Sufficiency range* July11, 2003 analysis July 8, 2004 analysisN (%) 3 - 3.5 4.02 3.73P (%) 0.3 - 0.4 0.45 0.41K(%) 1.7-2.1 5.88 2.52S (%) 0.3 - 0.4 0.22, deficient 0.64Ca (%) 0.8- 1.2 0.9 1.55Mg (%) 0.15 - 0.25 0.29 0.57

Zn (ppm) 15-25 36 29Mn (ppm) 70-110 81 115Cu(ppm) 3-5 12 16Fe (ppm) 65 - 95 256 205B (ppm) 35 - 45 17, deficient 25, deficient

analyses by Western Labs, Parma, ID.

100

0

C',

a)

0

0crj

104 161 218 275

Day of 2003

0

-20

-40

-60

-80

-100

0

-20

-40

-60

-80

-1001 294

Day of 2004

Figure 1. Average soil water potential at 8-inch depth during 2003 and 2004 for poplarclones irrigated with a drip-irrigation system with two emitters per tree, MalheurExperiment Station, Oregon State University, Ontario, OR.

101

60 118 177 235

a)C.)

(U

C-)

0CU

U)

CU

L..a)CU

a)>CU

E

0

U)

C-)

CU

0

C-)

CU

-oa)

CU

U)

CU

a)>CU

E

0

20

100 134 169 203

Day of 2003

238 272

15

10

5

0

40

30

20

10

0105 240 274

Day of 2004

Figure 2. Cumulative water applied to poplar clones in 2003 and 2004. Trees wereirrigated with a drip-irrigation system with two emitters per tree, Maiheur ExperimentStation, Oregon State University, Ontario, OR.

102

139 173 206

0)

Co

U)Ci)00-c0(0ci)

ci)>

10ci)

0 10 20 30 40 50 60

Relative leaf chlorophyll content, %

Figure 3. Relationship between relative leaf chlorophyll content measured with aMinolta SPAD meter and subjective rating of leaf chlorosis (0 = no chiorosis symptoms,5 = severe chiorosis symptoms), Malheur Experiment Station, Oregon State University,Ontario, OR.

103

5

a .. S S

3

Y = 6.14 - 0.13XR2 = 0.62, P = 0.001

2

0

Table 2. Performance of hybrid poplar clones planted on April 10, 2003 at the Maiheur Experiment Station, Oregon State University,Ontario, OR, 2004.

No. Clone CrossNovembe r2004 measurem. 2004 growth increment Leaf

chlorophyllcontent

Leafchlorosis

symptoms

Regression analysisof soil pH vs. leaf

chlorophyll content

TrunkdefectsHeight DBH Wood

volumeHeight DBH Wood

volumefeet inch inch3/tree feet inch inch3/tree 0 - 100 0 - 5* R2 Probability 0 - 2t

1 15-29 P. trichocarpaXP. deltoides 18.89 1.95 283.6 7.98 1.23 252.9 35.70 1.50 0.20 NS 1.002 50-184 P. trichocarpaXP. deltoides 13.02 1.63 119.3 5.66 1.19 113.3 31.10 2.50 0.67 0.001 1.003 50-197 P. trichocarpaXP. deltoides 20.20 2.19 348.5 10.07 1.45 333.2 30.30 3.00 0.38 0.05 0.254 52-225 P. trichocarpaXP. deitoides 18.77 1.93 252.1 9.90 1.35 240.5 26.60 3.00 0.81 0.001 0.505 55-260 P. trichocarpaXP. deltoides 16.62 1.80 203.6 7.24 1.25 191.7 25.80 2.75 0.58 0.001 0.756 56-273 P. trichocarpaXP. deltoides 19.81 2.11 318.6 10.10 1.48 303.1 40.80 1.00 0.13 NS 1.007 57-276 P. trichocarpaXP. deltoides 16.85 1.90 214.3 6.66 1.22 195.4 36.30 1.75 0.30 0.05 0.008 58-280 P. trichocarpaXP. deltoides 17.76 2.00 252.4 9.01 1.40 240.2 44.40 0.75 0.01 NS 0.759 59-289 P. trichocarpaXP. deltoides 22.56 2.30 437.0 10.07 1.35 414.2 42.00 0.50 0.12 NS 0.7510 184-401 P. trichocarpa XP. deltoides 20.39 2.41 407.1 7.24 1.26 385.5 34.00 0.50 0.26 NS 1.0011 184-411 P.trichocarpaXP.deltoides 19.61 2.05 312.5 10.02 1.38 300.4 32.40 1.50 0.43 0.01 0.5012 195-529 P. trichocarpaXP. deltoides 17.68 1.96 246.3 7.25 1.29 227.3 32.20 1.50 0.31 0.05 0.7513 309-74 P. trichocarpaXP. nigra 19.89 2.02 302.6 8.78 1.28 282.4 26.30 2.75 0.74 0.001 0.7514 311-93 P. trichocarpaXP. nigra 16.40 1.45 141.9 7.66 1.00 133.9 30.20 3.25 0.73 0.001 1.2515 NM-6 P. trichocarpaXP. maximowiczll 18.60 1.78 214.0 8.24 1.14 196.5 43.50 1.50 0.21 NS 1.2516 DTAC-7 P. trichocarpaXP. deltoides 15.18 1.66 171.0 7.25 1.20 162.5 34.00 2.00 0.43 0.01 0.7517 OP-367 P. deltoidesXP. nigra 18.10 2.10 284.9 8.14 1.46 269.1 40.60 0.00 0.26 NS 0.2518 PCi P. deltoidesXP. nigra 20.17 2.09 310.3 10.99 1.56 300.0 45.80 0.00 0.05 NS 0.2519 PC2 P. trichocarpaXP. deltoides 18.68 1.82 221.0 9.47 1.23 208.7 45.30 0.25 0.48 0.01 0.502049-177 P. trichocarpaXP. deltoides 18.75 1.82 237.8 9.46 1.24 228.7 33.50 1.50 0.33 0.05 1.7521 Malheur 1 P. deltoides, Malheur County, OR 19.79 1.53 186.4 10.16 1.01 176.7 49.30 0.00 0.02 NS 0.5022 Malheur2 P. deltoides, Malheur County, OR 18.18 1.59 177.8 8.14 0.94 167.7 46.70 0.00 0.09 NS 0.5023 Malheur3 P. deltoides, Malheur County, OR 19.92 2.37 407.9 9.64 1.59 396.1 42.20 0.00 0.19 NS 0.2524 DN-34 P. deltoidesXP. nigra 20.25 1.87 259.3 12.24 1.36 250.2 43.80 0.50 0.10 NS 0.25

LSD (0.05) 2.17 0.32 102.9 1.98 0.24 98.2 8.80 1.61 0.87

*Subjective evaluation of leaf chiorosis on a scale of 0-5: 0 = no symptoms, 5 = very chiorotic.tSubjective evaluation of trunk defects on a scale of 0-2: 0 = all trees have straight stems and single tops, Ihave either split or crooked stems, 2 = more than half of the trees have either split or crooked stems.

= less than half of trees

500

C.)

G) 300

100 Y=286.52-25.91X iR2 = 0.22, P = 0.001

00 1 2 3 4 5

Subjective leaf chlorosis rating

Figure 4. Relationship between leaf chlorosis symptoms (0 = no symptoms, 5 = severechlorosis symptoms) and stem volume in September 2004 for hybrid poplar clonessensitive to soil pH, Malheur Experiment Station, Oregon State University, Ontario, OR.

500

0)Y 118.8 + 3.53X

400 R2 0.15, P = 0.01. .

100 S •

C/)

00 10 20 30 40 50 60

Leaf chlorophyll content, %

Figure 5. Relationship between relative leaf chlorophyll content and stem volume inSeptember 2004 for hybrid poplar clones sensitive to soil pH, Malheur ExperimentStation, Oregon State University, Ontario, OR.

105

MICRO-IRRIGATION ALTERNATIVES FOR HYBRID POPLARPRODUCTION 2004 TRIAL



Summary

Hybrid poplar (cultivar OP-367) was planted for sawlog production in April 1997 at theMalheur Experiment Station. Five irrigation treatments were established in 2000 andwere continued through 2004. Irrigation treatments consisted of three water applicationrates using microsprinklers and two water application rates using drip tape. Irrigationscheduling was by soil water potential at 8-inch depth with a threshold for initiatingirrigations of -50 kPa in 2000 through 2002 and -25 kPa in 2003 and 2004. Increasingthe water application rate increased the annual growth in stem volume for themicrosprinkler-irrigated treatments. There was no significant difference between themicrosprinkler treatment irrigated at the highest rate and the drip-irrigated treatments interms of height, DBH, or stem volume growth in 2000 and 2001. In 2002 and 2003, dripirrigation with two tapes per tree row resulted in higher tree growth than microsprinklerirrigation. In 2004, the microsprinkler and the drip-irrigated treatments irrigated at thehighest rate had among the highest stem volume growth.

Introduction

With timber supplies from Pacific Northwest public lands becoming less available,sawmills and timber products companies are searching for alternatives. Hybrid poplarwood has proven to have desirable characteristics for many nonstructural timberproducts. Growers in Malheur County, Oregon have made experimental plantings ofhybrid poplars for saw logs and peeler logs. Clone trials in Malheur County during 1996demonstrated that the clone OP-367 (hybrid of Populus deltoides x P. nigra) grew wellon alkaline soils. Over the last 8 years OP-367 has continued to grow well on alkalinesoils. Some other clones have higher productivity on soils with nearly neutral pH.

Hybrid poplars are known to have high growth rates (Larcher 1969) and transpirationrates (Zelawski 1973), suggesting that irrigation management is a critical culturalpractice. Research at the Malheur Experiment Station during 1997-1999 determinedoptimum microsprinkler irrigation criteria and water application rates for the first 3 years(Shock et al. 2002). These results showed that tree growth was maximized by irrigatingat -25 kPa, but 38 irrigations were required for 3-year-old trees, and more wereanticipated for larger trees. Based on simplicity of operations, we decided to use anirrigation criterion of -50 kPa for the wettest treatments starting in 1998. In 2000 wenoticed that the rate of increase in annual tree growth started to decline in the wettest

106

treatment. One of the causes probably was the use of an irrigation criterion of -50 kPa.Starting in 2003 the irrigation criterion was changed to -25 kPa for the wettesttreatment. The objectives of this study were to evaluate poplar water requirements andto compare microsprinkler irrigation to drip irrigation.


Establishment. The trial was conducted on a Nyssa-Maiheur silt loam (bench soil)with 6 percent slope at the Malheur Experiment Station. The soil had a pH of 8.1 and0.8 percent organic matter. The field had been planted to wheat for the 2 years prior topoplar and to alfalfa before wheat. In the spring of 1997 the field was marked using atractor, and a solid-set sprinkler system was installed prior to planting. Hybrid poplarsticks, cultivar OP-367, were planted on April 25, 1997 on a 14-ft by 14-ft spacing. Thesprinkler system applied 1.4 inches on the first irrigation immediately after planting.Thereafter the field was irrigated twice weekly at 0.6 inches per irrigation until May 26.A total of 6.3 inches of water was applied in 9 irrigations from April 25 to May 26, 1997.

In late May 1997, a microsprinkler system (R-5, Nelson Irrigation, Walla Walla, WA)was installed with the risers placed between trees along the tree row at 14-ft spacing.The sprinklers delivered water at 0.14 inches/hour at 25 psi with a radius of 14 ft. Thepoplar field was used for irrigation management research (Shock et al. 2002) andgroundcover research (Feibert et al. 2000) from 1997 through 1999.

Procedures common to all treatments. In March 2000 the field was divided into 20plots, each of which was 6 tree rows wide and 7 trees long. The plots were allocated tofive treatments arranged in a randomized complete block design and replicated fourtimes (Table 1). The microsprinkler-irrigation treatments used the existing irrigationsystem. For the drip-irrigation treatments, either one or two drip tapes (NelsonPathfinder, Nelson Irrigation Corp., Walla Walla, WA) were laid along the tree row inearly May 2000. The plots with 2 drip tapes per tree row had the drip tapes spread 2 ftapart, centered on the tree row. The drip tape had emitters spaced 12 inches apart anda flow rate of 0.22 gal/min/100 ft at 8 psi. Each plot had a pressure regulator (set to 25psi for the microsprinkler plots and 8 psi for the drip plots) and a ball valve allowingindependent irrigation. Water application amounts were monitored daily by watermeters in each plot.

Soil water potential (SWP) was measured in each plot by 6 granular matrix sensors(GMS; Watermark Soil Moisture Sensors model 200SS; Irrometer Co. Inc., Riverside,CA); 2 at 8-inch depth, 2 at 20-inch depth, and 2 at 32-inch depth. The GMS wereinstalled along the middle row in each plot and between the riser and the third tree.The GMS were previously calibrated (Shock et al. 1998) and were read at 8:00 a.m.daily starting on May 2 with a 30 KTCD-NL meter (Irrometer Co. Inc., Riverside, CA).The daily GMS readings were averaged separately at each depth within each plot andover all plots in a treatment. Irrigation treatments were started on May 2.

107

The five irrigation treatments consisted of three water application rates for themicrosprinkler-irrigated plots and two water application rates for the drip-irrigated plots(Table 2). From 2000 through 2002, all plots in the 3 microsprinkler-irrigatedtreatments were irrigated whenever the SWP at 8-inch depth, averaged over all plots intreatment 1, reached -50 kPa. The plots in each drip-irrigated treatment were irrigatedwhenever the SWP at 8-inch depth, averaged over all plots in the respective treatment,reached -50 kPa. Irrigation treatments were terminated on September 30 each year.

Soil water content was measured with a neutron probe. Two access tubes wereinstalled in each plot along the middle tree row on each side of the fourth tree betweenthe sprinklers and the tree. Soil water content readings were made twice weekly at thesame depths as the GMS. The neutron probe was calibrated by taking soil samplesand probe readings at 8-inch, 20-inch, and 32-inch depth during installation of theaccess tubes. The soil water content was determined gravimetrically from the soilsamples and regressed against the neutron probe readings, separately for each soildepth. The regression equations were then used to transform the neutron probereadings during the season into volumetric soil water content. Coefficients ofdetermination (r2) for the regression equations were 0.89, 0.88, and 0.81 at P = 0.001for the 8-inch, 20-inch, and 32-inch depths, respectively.

The heights and diameter at breast height (DBH, 4.5 ft from ground) of the central threetrees in the two middle rows in each plot were measured monthly from May throughSeptember. Tree heights were measured with a clinometer (model PM-5, Suunto,Espoo, Finland) and DBH was measured with a diameter tape. Stem volumes(excluding bark and including stump and top) were calculated for each of the central sixtrees in each plot using an equation developed for poplars that uses tree height andDBH (Browne 1962). Growth increments for height, DBH, and stem volume werecalculated as the difference in the respective parameter between October of the currentyear and October of the previous year. Curves of current annual increment (CAl) andmean annual increment (MAI) over the 8 years for the treatment 1microsprinkler-irrigated trees and for the 2 drip tape configurations were used to assessthe growth stage of the plantation. The CAl is the current increment in stem volumeand the MAI is the CAl divided by the tree age.

2000 Procedures. The side branches on the bottom 6 ft of the tree trunk had beenpruned from all trees in February, 1999. In March of 2000, another 3 ft of trunk werepruned, resulting in 9 ft of pruned trunk. The pruned branches were flailed on theground and the ground between the tree rows was lightly disked on April 12. On April24, Prowl® at 3.3 lb ai/acre was broadcast for weed control. The microsprinkler-irrigatedplots received 0.7 inch of water to incorporate the Prowl. To control the alfalfa andweeds remaining from the previous years' groundcover trial in the top half of the field,Stinger® at 0.19 lb ai/acre was broadcast between the tree rows on May 19, andat 0.23 lb ai/acre was broadcast between the tree rows on June 1. On June 14,Stinger at 0.19 lb ai/acre and Roundup® at 3 lb ai/acre were broadcast between the treerows on the whole field.

108

On May 19 the trees received 50 lb nitrogen (N)/acre as urea-ammonium nitratesolution injected through the microsprinkler system. Due to deficient levels of leafnutrients in early July, the field had the following nutrients in pounds per acre injected inthe irrigation systems: 0.4 lb boron (B), 0.6 lb copper (Cu), 0.4 lb iron (Fe), 5 lbmagnesium (Mg), 0.25 lb zinc (Zn), and 3 lb phosphorus (P). The field was sprayedaerially for leafhopper control with Diazinon AG500® at 1 lb ai/ac on May 27 and withWarrior® at 0.03 lb al/acre on July 10.

2001 Procedures. In March of 2001, another 3 ft of trunk were pruned, resulting in 12ft of pruned trunk. The pruned branches were flailed on the ground on April 2. On April4, Roundup at 1 lb ai/acre was broadcast for weed control. On April 10, 200 lb N/acre,140 lb P/acre, 490 lb Sulfer (S)/acre, and 14 lb Zn/acre (urea, monoammoniumphosphate, zinc sulfate, and elemental sulfur) were broadcast. The ground betweenthe tree rows was lightly disked on April 12. On April 13, Prowl at 3.3 lb al/acre wasbroadcast for weed control. The microsprinkler-irrigated plots received 0.8 inch of waterto incorporate the Prowl.

A leafhopper, willow sharpshooter (Graphocephala con fluens, Uhier), was monitored bythree yellow sticky traps attached to the lower trunk of selected trees. Traps werechecked weekly. From mid-April to early June only adults were observed in the traps.A willow sharpshooter hatch was observed on June 6 as large numbers of nymphswere noted in the traps and on the lower trunk sprouts. The field was sprayed aeriallywith Warrior at 0.03 lb al/acre on June 11 for leafhopper control.

2002 Procedures. In March of 2002, another 3 ft of trunk were pruned, resulting in 15ft of pruned trunk. The pruned branches were flailed on the ground on April 12. OnApril 23, 80 lb N/acre, 40 lb Potassium (K)/acre, 150 lb S/acre, 20 lb Mg/acre, 6 lbZn/acre, 1 lb Cu/acre, and 1 lb B/acre (urea, potassium/magnesium sulfate, elementalsulfur, zinc sulfate, copper sulfate, and boric acid) were broadcast and the field wasdisked. On April 24, Prowl at 3.3 lb al/acre was broadcast for weed control. Themicrosprinkler-irrigated plots received 0.7 inch of water to incorporate the Prowl.

The willow sharpshooter was monitored by three yellow sticky traps attached to thelower trunk of selected trees. Traps were checked weekly. The field was sprayedaerially with Warrior at 0.03 lb ai/acre on June 10 for leafhopper control.

2003 Procedures. In March of 2003, another 3 ft of trunk were pruned, resulting in 18ft of pruned trunk. The pruned branches were flailed on the ground on March 31. OnApril 23, 80 lb N/acre as urea and 167 lb S/acre as elemental sulfur were broadcast andthe field was disked. On April 16, Prowl at 3.3 lb ai/acre was broadcast for weedcontrol. The microsprinkler-irrigated plots received 0.4 inch of water to incorporate theProwl.

Starting in 2003 the irrigation criterion was changed to -25 kPa and the water applied ateach irrigation was reduced accordingly (Table 2). All plots in the threemicrosprinkler-irrigated treatments were irrigated whenever the SWP at 8-inch depth,

109

averaged over all plots in treatment 1 reached -25 kPa. The plots in each drip-irrigatedtreatment were irrigated whenever the SWP at 8-inch depth, averaged over all plots inthe respective treatment, reached -25 kPa. Irrigation treatments were terminated onSeptember 30.

The drip tape needed to be replaced because iron sulfide plugged the emitters. Thedrip tape was replaced with another brand (T-tape, T-systems International, San Diego,CA) in mid-April because Nelson Irrigation discontinued production of drip tape. Thedrip tape specifications were the same.

The willow sharpshooter was monitored by three yellow sticky traps attached to thelower trunk of selected trees. Traps were checked weekly. The field was sprayedaerially with Warrior at 0.03 lb ai/acre on June 5 for leafhopper control.

2004 Procedures. On March 31, 2004, N at 80 lb/acre, S at 250 lb/acre, P at 50lb/acre, K at 50 lb/acre, Cu at 1 lb/acre, Zn at 4 lb/acre, and B at I lb/acre were

broadcast. The field was lightly disked on April 1. On April 13, Prowl at 3.3 lb ai/acre

was broadcast for weed control. The microsprinkler-irrigated plots received 0.4 inch ofwater to incorporate the Prowl. On June 12 the field was sprayed with Warrior at 0.03lb ai/acre for leafhopper control. A leaf tissue sample taken on July 7 showed a Pdeficiency. On July 9, P at 10 lb/acre as phosphoric acid was injected through thesprinkler and drip systems.


In 2004, the microsprinkler-irrigated treatment with 1 inch of water applied at eachirrigation received 51.7 acre-inch/acre of water in 43 irrigations (Table 1). The driptreatment with 1 inch of water applied with 2 tapes received 56 acre-inch/acre applied in38 irrigations. The drip treatment with 0.5 inch of water applied with 1 tape received 34acre-inch/acre in 44 irrigations. The large discrepancies between the number ofirrigations applied and the actual amount of water applied can be explained byinefficiencies in the irrigation system, such as leaks caused by rodent damage. Thetree squirrel population in an adjacent walnut orchard was inadvertently allowed toincrease, resulting in extensive damage to the drip and microsprinkler irrigation systemsin the spring of 2004. Repairs to the irrigation system and squirrel control measuresbrought the situation under control by mid-June.

In November 2004 (eighth year), trees in the wettest sprinkler-irrigated treatment andthe 2-drip-tape configuration had the highest stem volume (Table 2). In November2004, trees in the wettest sprinkler-irrigated treatment averaged 67 ft in height, 9 inch inDBH, and 2,459 ft3/acre in stem volume (Table 2). In November 2004, trees in thedrip-irrigated treatment with 2 drip tapes per tree row averaged 70 ft in height, 9.6 inchin DBH, and 2,653 ft3/acre in stem volume. Trees in the wettest sprinkler-irrigatedtreatment and the 2 drip-tape configuration had among the highest accumulated treegrowth from 2000 through 2004.

110

Comparing all treatments, drip irrigation with two tapes per tree row or the wettestsprinkler-irrigated treatment (water application rate of 1 inch) resulted in among thehighest stem volume growth in 2004, although the differences in tree growth during2004 were not statistically significant (Table 2).

Although tree growth increased with increasing applied water up to the highest amounttested, tree growth was not maximized in this study (Fig. 1). There were similar linearrelationships, with similar slopes, between total water applied and stem volume growthfor the drip and microsprinkler systems in 2004 (Y = -245.37 + 16.56X, R2 = 0.91, P =0.05 for the drip and Y = -393.37 + 20.14X, R2 0.91, P = 0.05 for the sprinkler).

For the period of 2000 through 2004, there were distinctively different linearrelationships, with similar slopes, between total water applied and the accumulatedstem volume growth for the drip and microsprinkler systems (Fig. 2). The greater stemvolume growth for the drip system reflected the higher water use efficiency of the dripsystem.

The soil water potential at 8-inch depth was maintained above the criterion of -25 kPa,except for brief periods during the season for microsprinkler irrigation with 1 inch ofwater applied and for drip irrigation with 2 tapes (Fig. 3). The soil water potential at8-inch depth was reduced, as expected, with the reductions in the water application ratein the sprinkler treatments (Fig. 3, Table 3). During irrigations the soil water potential at8-inch depth in the drip treatments was greater than in the sprinkler treatments, asexpected, since the wetted area was smaller with drip irrigation (Fig. 3). It was difficultto maintain the irrigation criterion with the one drip tape configuration because of thesmaller amount of water applied at each irrigation. With 1 drip tape, it takes 33 hours toapply 0.5 inch of water at each irrigation and usually about 30 hours later (the secondmorning after) the soil water potential would be equal to or considerably drier than -25kPa.

The rate of increase in annual stem volume growth increased (growth approximatelydoubled every year) up to 2001, when the stem volume growth for themicrosprinkler-irrigated trees started to decline (Table 4, Fig. 4). In 2002 the stemvolume growth for the drip-irrigated trees started to decline. The decline in annualgrowth was not expected until later, when the trees approach harvest size. Thereduction of the soil water potential from -25 to -50 kPa in 2000 might be associatedwith the decline in annual stem volume growth. Tree growth was substantially greaterin 2003 and was approximately double the growth in 2002; this could have been due tothe change to a wetter irrigation threshold from -50 to -25 kPa. In 2004, tree growthwas less than in 2003 for the microsprinkler-irrigated and drip-irrigated trees forunexplained reasons. There were fewer growing degree days (50-86°F) from Aprilthrough October in 2004 than in 2003 (Table 4).

Both the current annual increment (CAl) and the mean annual increment (MAI) continueto increase over time for the trees in treatment 1 (microsprinkler) and treatment 4 (drip,2 tapes)(Fig. 4). Typically, both the CAl and MAI initially increase, reach a culmination

111

point and then decline. The CAl will culminate before the MAI. The intersection of thetwo curves is termed the economic rotation and indicates the harvest stage of theplantation.

References


Feibert, E.B.G., C.C. Shock, and L.D. Saunders. 2000. Groundcovers for hybrid poplarestablishment, 1997-1999. Oregon State University Agricultural Experiment StationSpecial Report 1015:94-103.

Larcher, W. 1969. The effect of environmental and physiological variables on thecarbon dioxide exchange of trees. Photosynthetica 3:167-1 98.

Shock, C.C., J.M. Barnum, and M. Seddigh. 1998. Calibration of Watermark SoilMoisture Sensors for irrigation management. Pages 139-146 in Proceedings of theInternational Irrigation Show, Irrigation Association, San Diego, CA.


Wright, J.L. 1982. New evapotranspiration crop coefficients. J. Irrig. Drain. Div., ASCE108:57-74.

Zelawski, W. 1973. Gas exchange and water relations. Pages 149-165 in S. Bialobok(ed.) The poplars-Populus L. Vol. 12. U.S. Dept. of Comm., Nat. Tech. Info. Serv.,Springfield, VA.

112

Table 1. Irrigation rates, ato five irrigation regimes inOntario, OR.

mounts, and water use efficiency for hybrid2004, Malheur Experiment Station, Oregon

poplar submittedState University,

Water IrrigationTotal

number of Total water Water useTreatment Irrigation threshold application system irrigations applied* efficiency

kPat inch acre-inch!acre

ft3 ofwood!acre-inch of

water1 -25 1 Microsprinkler 43 51.7 12.92 coincide with trt #1 0.77 Microsprinkler 43 43.1 8.53 coincide with trt #1 0.39 Microsprinkler 43 26.4 6.74 -25 1 Drip, 2 tapes 38 56.3 12.05 -25 0.5 Drip, 1 tape 44 33.9 9.6

LSD (0.05) 1 9.4 NS

*lncludes 2.39 inches of precipitation from May through September.tSoil water potential at 8-inch depth.

Table 2. Height, diameter at breast height (DBH), and stem volume i2004, and 2004 growth in height, DBH, and stem volume for hybrid pfive irrigation treatments, Maiheur Experiment Station, Oregon State

n early Novemberoplar submitted toUniversity, Ontario,

OR.November 2004 2004 growth increment 2000-2004 growth

Treatment measurements incrementStem Stem Stem volume

Height DBH volume Height DBH volume

ft inch ft3/acre ft inch ft3!acre ft3!acre1 67.2 9.0 2,458.6 4.4 0.82 512.3 1,977.92 50.2 7.9 1,381.1 4.7 0.77 365.5 1,181.13 38.0 5.5 493.5 4.5 0.83 177.0 416.74 70.1 9.6 2,652.5 5.5 0.82 679.4 2,596.75 55.1 8.3 1,692.9 3.4 0.59 323.3 1,510.1

LSD (0.05) NS 1.0 583.4 NS NS NS 730.1

113

Table 3. Avesubmitted toUniversity, 0

rage soil water pfive irrigation treantario, OR.

otential and volumetric soil water content fortments, Malheur Experiment Station, Oregon

hybrid poplarState

TreatmentAverage soil water potential

1St ft 2nd ft 3rd ftkPa

1 22.2 21.6 19.12 32.9 33.1 30.43 99 58.9 72.44 20.2 22 22.85 30 16.7 20.6

LSD (0.05) 35.0* 13.0 6.5*significant at P = 0.10.

Table 4. Annual stem volume growth, seasonal average soil water potential at 8-inchdepth, and growing degree days for the drip and microsprinkler treatments receiving themost water, Malheur Experiment Station, Oregon State University, Ontario, OR.

Annual stem volume Seasonal average soil watergrowth potential at 8-inch depth April - Oct. Growing degree

Year Drip Microsprinkler Drip Microsprinkler days (50 - 86°F)ft3/acre ---- ---- kPa

1997 1.3 -21.4 3,0491998 78.5 -20.0 2,9681999 177.7 -22.2 2,8462000 387.9 401.5 -24.2 -37.9 3,0672001 479.9 354.7 -26.4 -33.9 3,1182002 440.1 256.8 -31.3 -35.8 3,0232003 737.9 450.7 -21.8 -26.9 3,3542004 679.4 512.3 -20.2 -22.2 3,106

114

0 10 20 60

Figure 1. Response of stem volume growth to water applied in 2004 for the drip andmicrosprinkler systems combined, Malheur Experiment Station, Oregon StateUniversity, Ontario, OR.

0 100 200 300

Water applied, inch

Figure 2. Response of stem volume growth to water applied from March 2000 throughNovember 2004 for the drip and microsprinkler systems. Malheur Experiment Station,Oregon State University, Ontario, OR.

115

2004

U)

C)Co

4-'a)

0I—0)U)

E

0>EU)4-'(I)

800

600

400

200

0

Y = -162.20 + 13.49XR2= 0.65, P= 0.01

S

S

S

S

30 40 50

Water applied, inch

ci)

C-)

CO

4-'ci)

00)a)E

0>EU)4-'

C')

3000 -

2000

1000

0

DripY=-24.05+1089X

R2= 0.94, P= 0.05+

+ #S #

+

a-p.

MicrosprinklerY = -792.29 + 12.63X

R2= 0.73, P= 0.05

0

0

0 -

20-inch 32-inch

microsprinkler, -25 kPa, 1 inch

microsprinkler, 0.77 inch

microsprinkler, 0.39 inch——..

———S.

-25

-500

-25

-500

-25

-50

-75

-1000

-25

-50

0

-25

-50172 260

Day of 2004

Figure 3. Soil water potential at three depths using granular matrix sensors in a poplarstand submitted to five irrigation regimes, Maiheur Experiment Station, Oregon StateUniversity, Ontario, OR.

116

194 216 238

0)0('3

Cci)

Eci)

0

a)E

0>Eci)

(I)

a)(-)('3

Ca)Ea)0C

ci)

E

0>Ea)

4—(I)

CAl - MAI

CAl MAI

Drip

1997 1998 1999 2000 2001 2002 2003 2004

Year

800

600

400

200

0

800 - -

Sprinkler

600

1997 1998 1999 2000 2001 2002 2003 2004

Year

Figure 4. Current annual increment (CAl, annual stem volume growth) and meanannual increment (MAI, mean annual stem volume growth) starting at planting in 1997through the eighth year for hybrid poplar irrigated with two drip tapes per tree row andwith microsprinklers. Data are from plots receiving the highest irrigation rates, MalheurExperiment Station, Oregon State University, Ontario, OR.

117

EFFECT OF PRUNING SEVERITY ON THE ANNUAL GROWTHOF HYBRID POPLAR

Clinton Shock, Erik Feibert, and Jake EatonMalheur Experiment Station


Summary

Hybrid poplar (clone OP-367) planted at 14-ft by 14-ft spacing was submitted to 5pruning treatments. Pruning treatments consist of the rate at which the side branchesare removed from the tree to achieve an 18-ft branch-free stem. Starting with a 6-ft(from ground) pruned trunk, 3-year-old trees are pruned to 18 ft in either 3, 4, or 5years. Starting in March 2000, the side branches on the trunk were pruned to a heightof 6, 9, or 12 ft. In subsequent years, the trees were pruned in 3-ft increments annually.A check treatment where trees were pruned only to 6 ft was included. In 2004 thepercentage of the total tree height that was pruned ranged from 12 percent for thecheck treatment to 35 percent. Stem volume growth in 2004 and over the previous 5seasons was not affected by pruning up to 23 percent of the total tree height.

Introduction

With reductions in timber supplies from Pacific Northwest public lands, sawmills andtimber products companies are searching for alternatives. Hybrid poplar wood hasproven to have desirable characteristics for many timber products. Growers in MaiheurCounty, Oregon have made experimental plantings of hybrid poplar and demonstratedthat the clone OP-367 (hybrid of Populus deltoides x P. nigra) performs well on alkalinesoils for at least 7 years of growth. Research at the Maiheur Experiment Station during1997-1999 determined optimum irrigation criteria and water application rates for the first3 years (Shock et al. 2002).

Pruning the side branches of trees allows the early formation of clear, knot-free wood inthe trunk and increases the trees' value as saw logs and peeler logs. The amount oflive crown removed might have an effect on tree growth. More severe pruning mightimprove the efficiency of the pruning operation (fewer pruning operations to reach thefinal pruning height), but could reduce growth excessively. The timing of pruning couldalso affect the amount of epicormic sprouting (sprouts forming on pruned stem) duringthe season, wound healing, and insect damage at wound sites. The objective of thisstudy was to evaluate the effect of pruning severity and timing on tree growth andhealth.

118


The trial is being conducted on a Nyssa-Malheur silt loam (bench soil) with 6 percentslope at the Maiheur Experiment Station. The soil had a pH of 8.1 and 0.8 percentorganic matter. The field had been planted to wheat for the 2 years prior to 1997 andbefore that to alfalfa. Hybrid poplar sticks, cultivar OP-367, were planted on April 25,1997 on a 14-ft by 14-ft spacing. The field was used for irrigation managementresearch (Shock et al. 2002) and groundcover research (Feibert et al. 2000) from 1997through 1999. All side branches on the lower 6 ft of all trees had been pruned inFebruary 1999.

In March 2000, the field was divided into 20 plots that were 6 rows wide and 7 treeslong. The plots were allocated to five irrigation treatments that consisted ofmicrosprinkler irrigation with three irrigation intensities and drip irrigation. Themicrosprinkler-irrigated plots used the existing irrigation system. For the drip-irrigatedplots, either one or two drip tapes (Nelson Pathfinder, Nelson Irrigation Corp., WallaWalla, WA) were laid along the tree row in early May 2000. The management of theirrigation trial is discussed in an accompanying article (see "Mircro-irrigation Alternativesfor Hybrid Poplar Production, 2004 Trial" in this report).

For the pruning study, only plots in the two wetter microsprinkler-irrigated treatmentsand the drip-irrigated treatments were used. The trees in the two wettermicrosprinkler-irrigated treatments and the drip-irrigated treatments averaged 26 ft inheight and 4.2 inches diameter at breast height (DBH) in March 2000. The middle 2rows in each irrigation plot were assigned to pruning treatment 3 (Table 1). Theremaining 2 pairs of border rows in each plot were randomly assigned to pruningtreatments 2, 4, and 5. The pruning treatments were replicated eight times. The treesin treatments 2, 3, and 4 were pruned on March 27, 2000; March 14, 2001; March 12,2002; March 12, 2003; and March 19, 2004. Trees in treatment 5 were pruned on May16, 2000; May 21, 2001; May 15, 2002; and May 14, 2003. Trees were pruned bycutting all the side branches up to the specified height on the trunk, measured fromground level. The side branches were cut using loppers and pole saws. An additional4 plots, in which the trees would remain pruned only to 6 ft, were selected for a checktreatment (treatment 1).

The five central trees in the middle two rows and the five central trees in each insiderow of each border pair in each plot were measured monthly for DBH and height. Trunkvolumes were calculated for each of the measured trees in each plot using an equationdeveloped for poplars that uses tree height and DBH (Browne 1962). Growthincrements for height, DBH, and stem volume for 2004 were calculated as thedifference in the respective parameter between October 2003 and October 2004.Growth increments for the five seasons (2000-2004) were calculated as the differencein the respective parameter between October 1999 and October 2004. Regressionanalyses were run for the percent of total tree height that was pruned trunk against treegrowth. The maximum percent of total trunk height pruned that would not reduce treegrowth was calculated by the first derivative (maximum = -b/2c) of the regression

119

equation Y = a + b • X + c • X2, where Y is the trunk volume increment and X is thepercent of the total height pruned.


In 2004, the trees in the least intensive pruning treatment (treatment 2) were pruned to18-ft height, completing the pruning treatments. In October 2004 the trees in the leastsevere pruning treatment (treatment 2) averaged 65.2 ft in height and 9.3 inches DBH.In 2003 the percentage of the total tree height that was pruned ranged from 12 percentfor the check treatment to 35 percent for treatment 5 (Table 1). The differences in thepercentage of the total tree height that was pruned trunk between treatments 2, 3, 4,and 5 was not significant in 2004, as all trees in these treatments were branch-free to18 ft.

Tree growth increased, reached a maximum, and then decreased with increasingpruning severity, both in 2004 and over the 4 years (Figs. I and 2). The response oftree growth to pruning suggests that pruning up to a certain severity is beneficial for treegrowth. Pruning removes branches from the lower canopy that might not contributemuch to the photosynthetic capacity of the tree due to shading. Pruning also changesthe trunk shape, with greater diameter growth occurring higher on the trunk than inunpruned trees. The maximum trunk volume growth was achieved by limiting thelength of pruned stem to 22 percent of the total tree height in 2004 and to 23 percent ofthe total tree height over the 4 years. Future tree measurements will determine if treessubjected to the most severe pruning will eventually reach the same size as lessseverely pruned trees. Tree growth reductions that occurred when trunks were prunedabove 25 percent of total tree height, as shown in this study, are inconsistent with theOregon State University Extension recommendation to limit pruning to 50 percent oftotal height (Hibbs 1996).

Lower intensity pruning might increase pruning costs, because there will be morepruning events before an 18-ft branch-free trunk is achieved than with higher intensitypruning. Lower intensity pruning will also result in larger branches being pruned, whichincreases labor costs and results in less clear wood.

References


Feibert, E.B.G., CC. Shock, and L.D. Saunders. 2000. Groundcovers for hybrid poplarestablishment, 1997-1999. Oregon State University Agricultural Experiment StationSpecial Report 1015:94-103.

120

Hibbs, D.E. 1996. Managing hardwood stands for timber production. The WoodlandWorkbook, Oregon State University Extension Service, Oregon State University,Corvallis.


Table I. Poplar pruning treatments and actual percentage of total height pruned(percentage of total height that is branch-free stem after pruning) in successive years.The amount of sprouting for trees pruned in winter is compared to spring. Trees wereplanted in April 1 997, Malheur Experiment Station, Oregon State University, Ontario,OR.

Actual percentage of total tree heightPruning height* (ft from ground) that was pruned trunk in March

Treatment 1999 2000 2001 2002 2003 2004 2000 2001 2002 2003 20041 Check 6 6 6 6 6 6 24.3 15.7 13.7 12.9 11.7

2 6 6 9 12 15 18 22.2 22.9 26.1 28.1 30.53 6 9 12 15 18 18 33.7 29.3 32.0 35.3 32.24 6 12 15 18 18 18 47.3 39.4 35.2 33.5 30.0

6 9 12 15 18 18 33.7 31.5 34.8 38.7 35.0LSD (0.05) 2.7 2.1 3.5 3.0 3.4*Trunk height to which all side branches were removed in March of the respective year.

in May. All others were pruned when trees were dormant.

121

15

12

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3I0

0 10 20 30 40 50

C-)

-I-i

05.-C)I

cU

0o0 10 20 30 40 50

(Y)

05.-0)4U)

E

0>

0

Percent of total trunk height pruned

Figure 1. Poplar tree annual growth increment in 2004 in response to pruning severity,Maiheur Experiment Station, Oregon State University, Ontario, OR.

122

Y=-318+0.819X-0.0175X2r2 = 0.19, P = 0.001

• S• •• •. •SS S •S.

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• .s) 's

10 20 30 40 50

-C

00)

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Percent of total trunk height pruned

Figure 2. Poplar tree 5-year (2000-2004) growth in response to pruning severity,Maiheur Experiment Station, Oregon State University, Ontario, OR.

123

S

jS.

.1S.S

S S.

Y = -2.45 + 3.61X - 0.0785-- r2 = 0.54, P = 0.0001

10 20 30 40

S. S

0

S

0C

0C)Ia

50

40

30

20

10

0

8

6

4

2

0

16

14

12

10

8

6

4

2

0

S

S

Y=3.35+0.2197X+0.0054X2r2 = 0.37, P 0.00 1

S

0 10 20 30 40 50

Y -2.40 + 1.17X + 0.0256X2= 0.42, P 0.0010

0)0)E

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=

F-

S.S. S

•SS•5

S

S

0 10 20 30 40 50

SOYBEAN PERFORMANCE IN ONTARIO IN 2004

Erik B.G. Feibert, Clinton C. Shock, and Lamont D. SaundersMalheur Experiment Station


Introduction

Soybean is a potentially valuable new crop for Oregon. Soybean could provide a highquality protein for animal nutrition and oil for human consumption, both of which are inshort supply in the Pacific Northwest. In addition, edible or vegetable soybeanproduction could provide a raw material for specialized food products. Soybean isvaluable as a rotation crop because of the soil-improving qualities of its residues and itsN2 -fixing capability. Because of the high-value irrigated crops typically grown in theSnake River Valley, soybeans may be economically feasible only at high yields.

Soybean varieties developed for the midwestern and southern states are notnecessarily well adapted to Oregon's lower night temperatures, lower relative humidity,and other climatic differences. Previous research at Ontario, Oregon has shown that,compared to the commercial cultivars bred for the Midwest, plants for eastern Oregonneed to have high tolerance to seed shatter and lodging, reduced plant height,increased seed set, and higher harvest index (ratio of seed to the whole plant).

M. Seddigh and G.D. Jolliff at Oregon State University, Corvallis identified a soybeanline that would fill pods when subjected to cool night temperatures. This line wascrossed at Corvallis with productive lines to produce OR 6 and OR 8, among others. Atthis point, the development moved to Ontario, Oregon. The later two lines werecrossed at our request for several years with early-maturing high-yielding semi-dwarflines by R.L. Cooper (USDA, Agriculture Research Service, Wooster, OH) to producesemi-dwarf lines with potential adaptation to the Pacific Northwest. Selection criteria atthe Malheur Experiment Station (MES) included high yield, zero lodging, zero shatter,low plant height, and maturity in the available growing season. In 1992, 241 singleplants were selected from 5 F5 lines that were originally bred and selected foradaptation to eastern Oregon. Seed from these selections was planted and evaluatedin 1993; 18 selections were found promising and selected for further testing in largerplots from 1994 through 1999. Of the 18 lines, 8 were selected for further testing. In1999, selections from one of the MES lines were made by P. Sexton at the CentralOregon Agricultural Research and Extension Center (COAREC) in Madras, Oregon.Sixteen of these Madras selections were chosen for further testing. In 2000, selectionswere made from six of the 1992 MES lines and from OR-6. This report summarizeswork done in 2004 as part of the continuing breeding and selection program to adaptsoybeans to eastern Oregon.

124

Methods

The trial was conducted on a Greenleaf silt loam previously planted to wheat. Forty lbsof nitrogen, 100 lb of sulfur, 2 lb of copper, and 1 lb of boron were broadcast in the fallof 2003. The field was then disked twice, moldboard plowed, groundhogged twice, andbedded to 22-inch rows.

Five commercial cultivars, 5 older lines selected at MES in 1992, 9 lines selected in1999 at the COAREC from a MES line, and 24 lines selected in 2000 at MES wereplanted in plots 4 rows by 25 ft. The plots were arranged in a randomized completeblock design with four replicates. The seed was planted on May 20 at 200,000seeds/acre in rows 22 inches apart. Rhizobiumjaponicum soil implant inoculant wasapplied in the seed furrow at planting. Emergence started on June 1. The field wasfurrow irrigated as necessary. The field was sprayed on August 3 and August 11 withdimethoate at 0.5 lb ai/acre for lygus bug and stinkbug control.

Plant height and reproductive stage were measured weekly for each cultivar. Prior toharvest, each plot was evaluated for lodging and seed shatter. Lodging was rated asthe degree to which the plants were leaning over (0 = vertical, 10 = prostrate). Themiddle two rows in each four-row plot were harvested on October 8 using aWintersteiger Nurserymaster small plot combine. Beans were cleaned, weighed, and asubsample was oven dried to determine moisture content. Dry bean yields werecorrected to 13 percent moisture. Variety lodging, plant population, yield, and seedcount were compared by analysis of variance. Means separation was determined bythe protected least significant difference test.


Yields in 2004 ranged from 44.2 bu/acre for 'OR-8' to 70.5 bu/acre for 'M12' (Table 1).Several of the lines had seed counts sufficient for the manufacturing of tofu (<2,270seeds/Ib). Several lines combined high yields, little lodging, and early maturity.Considerable yield advantages were obtained through continued selection.

125

Table 1. Performance of soybean cultivars ranked by yield in 2004, MalheurExperiment Station, Oregon State University, Ontario, OR. Cultivars M92-085 throughM92-350 are from single plant selections made at the Malheur Experiment Station in1992. Cultivars Ml through M16 are from single plants selected from M92-330.

Cultivar Origin Days to maturity Days to harvest Lodging Height seeds/lb Yieldmaturity

days from emergence 0-10 cm seeds/lb bu/acreM12 M92-330 91 101 1.5 90 1,974 70.5M3 M92-330 91 101 2.5 103 2,052 68.7M9 M92-330 78 88 2.3 105 2,100 68.2108 M92-085 78 88 0.5 91 2,090 66.9104 M92-085 91 101 1.5 98 2,066 65.8312 M92-220 98 108 1.3 82 2,519 64.7303 M92-220 98 108 2.8 88 2,572 63.0309 M92-220 98 108 1.0 83 2,617 62.8M92-085 91 101 0.8 101 2,056 62.5M16 M92-330 91 101 1.0 94 2079 62.2601 M92-314 98 108 0.8 82 2,459 61.9M13 M92-330 91 101 1.5 105 2,119 61.8M15 M92-330 91 101 0.5 95 2,198 61.8107 M92-085 78 88 0.5 98 2,142 61.5106 M92-085 78 88 0.3 84 2,012 60.9103 M92-085 78 88 0.5 100 2,104 60.6Ml M92-330 91 101 0.8 97 2,123 60.3M2 M92-330 91 101 1.5 90 1,952 60.1311 M92-220 98 108 1.0 68 2,530 59.9101 M92-085 78 88 2.0 89 2,003 59.7313 M92-220 98 108 2.3 85 2,459 59.5308 M92-220 98 108 0.8 75 2,681 59.4M4 M92-330 91 101 1.3 89 2,081 58.1511 M92-237 98 108 1.5 81 2,666 58.0Korada 98 108 2.5 77 2,422 57.7M92-220 98 108 2.0 100 2,569 57.0M92-225 78 88 0.5 88 2,307 56.5608 M92-314 91 101 0.3 90 2,237 56.4307 M92-220 98 108 1.0 85 2,752 55.1905 OR-6 78 88 5.3 105 2,453 55.1514 M92-237 91 101 0.5 82 2,423 54.9305 M92-220 98 108 0.8 61 2,630 54.8909 OR-6 78 88 5.5 97 2,251 53.0Gnome 85 98 108 6.3 120 2,072 52.9Lambert 98 108 7.0 98 2,220 52.7Evans 98 108 8.0 111 2,072 50.9OR-6 91 101 5.3 101 2,309 50.1Sibley 98 108 8.8 115 1,946 49.0OR-8 98 108 7.8 106 1,894 44.2LSD (0.05) 1.5 244 8.4

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Table 2. Performance of soybean varieties over years, Malheur Experiment Station,Oregon State University, Ontario, OR.

Yield Averages 2002-2004

Cultivar 2002 2003 2004 Average Days tomaturity

Lodging Height Seedcount

bu/acre 0-10 cm seeds/lb

M12 65.7 56.1 70.5 64.1 94 3.5 86.0 2,071

M9 66.3 55.4 68.2 63.3 90 4.1 89.3 2,191

104 66.3 57.5 65.8 63.2 92 3.8 91.3 2,173

106 72.9 55.4 60.9 63.1 90 2.9 85.0 2,056

108 68.1 54.3 66.9 63.1 90 2.7 85.3 2,113

M92-085 64.1 61.6 62.5 62.7 97 3.0 90.3 2,121

M15 73.8 52.4 61.8 62.7 94 3.3 89.3 2,199

107 66.9 59.5 61.5 62.6 87 3.0 86.0 2,159

Ml 65.7 59.7 60.3 61.9 92 3.0 85.3 2,224

M13 70.4 53.2 61.8 61.8 92 3.3 89.0 2,250103 69.6 55.3 60.6 61.8 90 3.0 89.3 2,081

601 68.5 54.4 61.9 61.6 99 1.4 88.0 2,393M3 63.7 52.1 68.7 61.5 94 3.6 91.0 2,221

M16 65.7 55.6 62.2 61.2 92 2.3 92.3 2,155M2 65.0 57.9 60.1 61.0 97 3.6 87.3 2,093312 64.7 53.1 64.7 60.8 101 1.1 87.7 2,436303 64.2 54.7 63.0 60.6 101 2.7 89.0 2,465305 68.8 57.4 54.8 60.3 101 1.5 78.0 2,458Korada 67.2 55.2 57.7 60.0 101 4.1 80.0 2,410M4 66.1 55.3 58.1 59.8 94 2.7 83.7 2,198511 67.2 53.8 58.0 59.7 99 1.9 84.7 2,505307 69.1 54.5 55.1 59.6 99 1.7 86.3 2,528101 68.6 49.5 59.7 59.3 92 3.5 86.0 2,027313 63.6 53.8 59.5 59.0 103 3.5 88.7 2,445309 65.3 48.4 62.8 58.8 101 2.2 88.7 2,519M92-220 69.4 49.5 57.0 58.6 101 3.2 96.0 2,556308 65.7 49.4 59.4 58.2 103 0.7 83.7 2,539Lambert 62.9 58.6 52.7 58.1 103 7.8 88.3 2,355608 68.2 49.5 56.4 58.0 92 2.8 86.7 2,117514 66.4 52.5 54.9 57.9 89 0.9 83.3 2,264311 60.4 51.1 59.9 57.1 101 0.4 81.7 2,403M92-225 58.9 50.1 56.5 55.2 87 3.0 86.0 2,277Gnome 85 60.0 48.7 52.9 53.9 101 7.5 89.0 2,193909 53.3 53.2 53.0 53.2 90 6.8 89.0 2,271

905 48.6 50.3 55.1 51.3 90 7.0 88.3 2,361

OR-6 51.5 49.6 50.1 50.4 94 7.4 88.3 2,323Evans 51.3 41.0 50.9 47.7 103 8.7 91.7 2,214Sibley 51.0 40.5 49.0 46.8 108 8.8 91.3 2,156OR-8 45.3 39.4 44.2 43.0 103 8.4 86.0 2,123Average 63.9 52.8 59.0 58.5 96 3.7 87.4 2,273LSD (0.05) 10.1 10.7 8.4

127

POTATO VARIETY TRIALS 2004

Eric P. Eldredge, Clinton C. Shock, and Lamont D. SaundersMalheur Experiment Station


Introduction

New potato varieties were evaluated for their productivity and usefulness forprocessing. Potatoes are grown under contract in Malheur County, Oregon for potatoprocessors to produce frozen products for the food service industry. There is very littleproduction for fresh pack or open market, and very few growers have potato storagebuildings on their farms. There is also no production of varieties for making potatochips. Potato seed is not produced in Malheur County because high populations ofaphids result in virus infection in the tubers.

The varieties grown for processing are mainly 'Ranger Russet', 'Shepody', and 'RussetBurbank'. Harvest begins in July, and potatoes go to processing plants directly from thefield. Yields are limited by "early die" syndrome, which causes early senescence of thevines. Early die is caused by a complex of soil pathogens, including bacteria,nematodes, and fungi, and is worse when crop rotations between potato crops areshort.

Small acreages of new varieties or advanced selections are sometimes contracted tostudy the feasibility of expanding their use. To displace an existing processing variety, anew potato variety needs to have several outstanding characteristics. The yield shouldbe at least as high as the yield of Russet Burbank. The tubers need to have lowreducing sugars for light, uniform fry color, and high specific gravity. A new varietyshould be resistant to tuber defects or deformities caused by disease, water stress, orheat. It should begin tuber bulking early if it is a variety for early harvest. Or, if it is alate-harvest variety, it should be resistant to early die.

Potato variety development trials at Malheur Experiment Station (MES) in 2004included the Western Regional Early Harvest Trial with 20 entries, the WesternRegional Late Harvest Trial with 20 entries, the Oregon Statewide Trial with 29 entries,the Oregon Preliminary Yield Trial with 131 entries, a Malheur Preliminary Yield Trial of6 strains selected in previous 8-Hill trials at MES, and an 8-Hill trial of 84 clones fromthe USDA Agricultural Research Service (ARS) potato breeding program at Aberdeen,Idaho. Through these trials and active cooperation with other scientists in Idaho,Oregon, and Washington, promising new lines are bred, evaluated, and eventuallyreleased as new varieties.

128


Six potato variety trials were grown under sprinkler irrigation on Owyhee silt loam,where winter wheat was the previous crop in a potato, wheat, corn, wheat, potatorotation. The wheat stubble was flailed and the field was irrigated and disked. A soil testtaken on September 16, 2003 showed 37 lb nitrogen (N)/acre in the top 2 ft of soil, and102 lb available phosphate (P205), 851 lb soluble potash (1(20), 29 lb sulfate (SO4),1966 ppm calcium (Ca), 463 ppm magnesium (Mg), 87 ppm sodium (Na), 1.6 ppm zinc(Zn), 18 ppm iron (Fe), 4 ppm manganese (Mn), 0.7 ppm copper (Cu), 0.5 ppm boron(B), organic matter 3.5 percent, and pH 7.4 in the top foot of soil. Fall fertilizer wasspread to apply 60 lb N/acre, 50 lb P205/acre, 80 lb K20/acre, 57 lb sulfur (S)/acre, 8 lbZn/acre, 5 lb Cu/acre, and 1 lb B/acre. The field was ripped, Telone Il® soil fumigantwas injected at 25 gal/acre, and the field was bedded on 36-inch row spacing.

Seed of all varieties was hand cut into 2-oz seed pieces and treated with Tops-MZ®+Gaucho® dust one to two weeks before planting and placed in storage to suberize. OnMarch 22, 2004, the field was cultivated with a Lilliston rolling cultivator to reshape thehills and to control winter annual weeds and volunteer wheat. On April 2 a soil samplewas taken that showed 43 lb N/acre in the top 2 ft of soil, 83 lb available P205, 688 lbsoluble K2O, 26 lb SO4, 1,835 ppm Ca, 353 ppm Mg, 69 ppm Na, 1.1 ppm Zn, 5 ppmFe, 1 ppm Mn, 0.4 ppm Cu, 1.2 ppm B, pH 7.4, and 3.0 percent organic matter in thetop foot of soil.

Potato seed pieces were planted in single-row plots using a 2-row cup planter with9-inch seed spacing in 36-inch rows. Red potatoes were planted at the end of each plotas markers to separate the potato plots at harvest. After planting, hills were formed overthe rows with the Lilliston rolling cultivator. Prowl® at I lb/acre plus Dual® at 2 lb/acreherbicide was applied as a tank mix for weed control on May 7 and was incorporatedwith the Lilliston. Matrix® herbicide was applied at 1.25 oz/acre on May 17 and wasincorporated with 0.41 inch of rain on the next day, followed by 0.89 inch of additionalrain through the end of May.

The Western Regional Early Harvest Trial was planted on April 13, 2004. The WesternRegional Late Harvest and the 8-Hill Trial were planted on April 19. The Statewide Trialand the Preliminary Yield Trials were planted on April 26. The Malheur Preliminary YieldTrial, planted on April 26, consisted of 2 entries with sufficient seed available to plant 4replicates of 30 seed pieces, and 4 entries with enough seed available to plant 2replicates of 20 seed pieces. The 8-Hill trial was unreplicated with plots 8 seed pieceslong, the Oregon Preliminary Yield Trial had 2 replicates with plots 20 seed pieces long,and the Statewide, Western Regional Early Harvest, and Western Regional LateHarvest Trials each had 4 replicates with plots 30 seed pieces long.

Irrigation was applied 21 times (Fig. 1), from June 4 to August 30, with schedulingbased on soil water potential. The average readings of 6 Watermark soil moisturesensors (model 200 SS, lrrometer Co. Inc., Riverside, CA) were monitored every 8hours by a Hansen model AM400 datalogger (M. K. Hansen Co., East Wenatchee,

129

WA). Sensors were installed in the potato row at the seedpiece depth, 10 inches fromthe top of the hill. The AM400 unit was read frequently through the summer to predictcrop water needs; the objective was to apply an irrigation just before the average soilmoisture in the potato root zone at the seed piece depth reached -60 kPa (Fig. 2). Waterapplied was estimated by recording the sprinkler set duration at 55 psi, and using thenominal sprinkler head output. Crop evapotranspiration (ETa) was estimated by the U.S.Bureau of Reclamation based on data from an AgriMet weather station at MES.

Fungicide applications to control early blight and prevent late blight infection startedwith an aerial application of Ridomil Gold® and Bravo® at 1.5 pint/acre on June 12. OnJune 25, Headline® fungicide was applied; on July 17, Topsin-M® fungicide plus liquidsulfur with 1.5 lb P2O5/acre and 0.2 lb Zn/acre was applied by aerial applicator. OnAugust 8, Headline plus 6 lb S/acre was applied to prevent two-spotted spider miteinfestation and powdery mildew infection.

Petiole tests were taken every 2 weeks from June 14, and fertilizer was injected into thesprinkler line during irrigation to supply the crop nutrient needs. A total of 103 lb N/acre,44 lb P205/acre, 140 lb K2O/acre, 100 lb SO4/acre, 0.3 lb Mn/acre, 5 lb Mg/acre, 0.1 lbCu/acre, 0.1 lb Fe/acre, and 0.5 lb B/acre were applied.

Vines were flailed in the Western Regional Early Harvest Trial on August 16. WesternRegional Early Harvest Trial potatoes were lifted August 27 with a two-row digger thatlaid the tubers back onto the soil in each row. Visual evaluations included observationsof desirable traits, such as a high yield of large, smooth, uniformly shaped and sized,oblong to long, attractively russetted tubers, with shallow eyes evenly distributed overthe tuber length. Notes were also made of tuber defects such as growth cracks, knobs,curved or irregularly shaped tubers, pointed ends, stem-end decay, stolons thatremained attached, folded bud ends, rough skin due to excessive russetting, pigmentedeyes, or any other defect, and a note to keep or discard the clone based on the overallappearance of the tubers.

Tubers were placed into burlap sacks and hauled to a barn where they were kept undertarps until grading. After grading, a 20-tuber sample from each plot in the WesternRegional Early Harvest Trial was evaluated for tuber quality traits for processing.Specific gravity was measured using the weight-in-air, weight-in-water method. Tentubers per plot were cut lengthwise and the center slices were fried for 3.5 mm in 375°Fsoybean oil. Percent light reflectance was measured on the stem and bud ends of eachslice using a Photovolt Reflectance Meter model 577 (Seradyn, Inc., Indianapolis, IN),with a green tristimulus filter, calibrated to read 0 percent light reflectance on the blackstandard cup and 73.6 percent light reflectance on the white porcelain standard plate.

The vines were flailed on the late harvest trials on September 21. The vines of mostentries had died by the date of the last irrigation on August 30. Potatoes in the WesternRegional Late Harvest Trial were dug on October 5. The 8-Hill Trial tubers and thepotatoes in the Statewide Trial were dug on October 6-7, and the Preliminary Yield Trialtubers were dug on October 7-8. At each harvest, the potatoes in each plot were

130

visually evaluated as described above. Tubers were graded and a 20-tuber samplefrom each plot was placed into storage. The storage was kept near 90 percent relativehumidity and the temperature was gradually reduced to 45°F. Tubers were removedfrom storage November 19 through December 6 and evaluated for tuber quality traits,specific gravity, and fry color as described above. Data were analyzed with the GeneralLinear Models analysis of variance procedure in NCSS (Number Cruncher StatisticalSystems, Kaysville, UT) using the Fisher's Protected LSD means separation t-test atthe 95 percent confidence level.


At the Malheur Experiment Station in 2004, spring weather was cool and wet, followedby a summer without the usual extreme heat. Dry weather prevented late blight fromdeveloping in 2004. No powdery mildew or mite problems were observed in the field.Compared to the 2003 potato trials at this location, overall yields were lower by about17 percent, and specific gravity of the tubers was lower.

Precipitation during May 1 through September 30 was 2.55 inches, the cropevapotranspiration (EL) for the late-harvest trials totaled 26.19 inches, and the trialsreceived 22.15 inches of irrigation plus precipitation, or 84.6 percent of (Fig. 1). Thestep increases in the irrigation plus rainfall curve show the 21 sprinkler irrigationsapplied during the growing season.

The trend of soil moisture during the growing season is shown in Figure 2. The data donot show the individual irrigations because the sensors did not always respond to anirrigation. The irrigation plus rainfall was less than for the growing season, and thesensor data show that average root zone soil water potential became drier than -60 kPaat least four times during the growing season.

Soil water potential at the seed piece depth was allowed to become drier than -60 kPaat the end of the growing season, after the vines died on the early maturing entries, byapplying frequent sprinkler irrigations of short duration, as shown in Figure 1. This wasnecessary to avoid swollen lenticels and the associated possibility of rotting the tubersof the early entries, while continuing to apply a portion of the requirement for thelate maturing entries in shallow moisture increments.

Western Regional Early Harvest TrialIn the Western Regional Early Harvest Trial, among the highest in total yields were'A92294-6', 'Shepody', 'AC93026-9Ru', 'A93157-6LS', and 'TC1675-lRu' with totalyield ranging from 473 to 546 cwtlacre (Table 1). Of those clones, only TC1675-lRuhad specific gravity above 1.080 g cm3, a desirable level for processing. In productionof marketable tubers for processing (the total of U.S. No.1 pIus U.S. No. 2 grades),A92294-6, Shepody, AC93026-9Ru, A9305-10, TC1675-lRu, and A93157-6LS withmarketable yield from 423 to 499 cwt/acre were among the highest in marketable yield.

131

Western Regional Late Harvest TrialThe highest total yield In the Western Regional Late Harvest Trial was produced byA92294-6, with 658 cwt/acre, and it also produced the highest marketable yield, 632cwt/acre (Table 2). Among the highest producers of U.S. No. I tubers, on a percentagebasis, were 'AC92009-4Ru', 'ATX91137-lRu', and 'A096160-3', with ATX92230-lRu,'Russet Norkotah', and 'A95109-1', ranging from 84 to 94 percent. Among the highesttotal U.S. No. 1 tuber producers were ATX92230-lRu, A93157-6LS, A096160-3,A92294-6, A9305-10, 'A95074-6', and TC1675-lRu, ranging from 377 to 437 cwt/acre.Shepody, A92294-6, and Russet Burbank produced significantly more U.S. No. 2tubers than other clones in this trial. In this late-harvest trial, specific gravity ofA93157-6LS, AC92009-4Ru, A096160-3, Ranger Russet, A92294-6, A95074-6, andTC1675-lRu were among the highest, and acceptable for processing into frozen potatoproducts.

Oregon Statewide TrialIn the Oregon Statewide Trial, the six clones marked with an asterisk were retained bythe variety selection committee (Table 3). The clone AO96160-3 will stay in theStatewide Trial and in the Western Regional Trial, 'AO96164-1' will advance to theWestern Regional Trial, 'A096141-3' and 'A098133-2' will advance to the WesternRegional Russet Early and Late Harvest Trials, and 'A096162-1' and 'A099099-3' willbe maintained in the Statewide Trial in 2005. At this location in 2004, A096160-3,A096164-1, A096141-3, A098133-2, A096162-1, and AO99099-3 produced amongthe highest total yields, with a high percentage of U.S. No. I tubers, good specificgravity for processing, and light fry colors with no sugar ends. Russet Burbankproduced 102 cwt/acre U.S. No. 2 tubers, significantly more than any other entry, andhad 30 percent sugar ends.

Oregon Preliminary Yield TrialIn the Preliminary Yield Trial, 126 numbered clones were compared to Russet Burbank,Ranger Russet, Shepody, Russet Norkotah, and 'Umatilla Russet' (Table 4). TheOregon potato variety selection committee kept 11 clones, based on their performanceat Hermiston, Kiamath Falls, Powell Butte, and Ontario, to advance to the StatewideTrial for 2005. The clones that were advanced were 'AO96305-3' , 'A096365-2','A096370-2', 'AO98123-2', 'A098268-5', 'AO98282-5', 'A098307-6', 'A099065-2','A099081-1', 'AO99108-5', and 'A0991 11-9'. These clones yielded welt across the fourlocations (Hermiston, Klamath Falls, and Powell Butte data are not shown in thisreport), had a low incidence of undesirable characteristics, had high percentage of U.S.No. 1 tubers, and if selected as promising clones for processing, had high specificgravity, light fry color, and resistance to developing sugar ends in response to stress.

Malheur Preliminary TrialThis was the first year of a Malheur Preliminary Trial, a cooperative project by theMalheur Agricultural Experiment Station and the USDA-ARS. Six clones from previous8-Hill trials at Malheur were selected for their adaptation to the high early die pressure,heavy soil texture, and hot, dry climate of the Treasure Valley. These clones werecompared to Russet Burbank, Ranger Russet, and Umatilla Russet (Table 5). The

132

clones 'A98345-1', 'A91814-2', 'A961 12-20', produced a high percentage of U.S. No. Itubers, had specific gravity above 1.080 g cm3 (a level desirable for processing), andproduced no sugar ends. The clones 'A99133-6' and 'A99123-1' each produced 5percent sugar ends, and 'A96783-1O9LB', produced 15 percent sugar ends.

8-Hill TrialEight hills were grown of each of 84 clones selected for long, russet tubers from theAberdeen ARS potato breeding program, including 17 clones with the LB suffixsignifying that they were bred for resistance to late blight. The 84 clones were evaluatedfor tuber type, yield, grade, and processing quality (Table 6). Yield and grade data wereexamined for clones having total yield greater than 530 cwtlacre and U.S. No. 1 tubersat 93 percent or higher, without excessive U.S. No. 2, cull, or undersized (less than 4oz) tubers. Twenty-six of the clones had high yields and produced a high percentage ofU.S. No. 1 tubers. Samples of these clones were analyzed for processing quality. Theclone 'C0A00329-1' yielded a total of 695 cwt/acre, with 85 percent U.S. No. 1 tubers,specific gravity of 1.092 g cm3, and an average fry strip light reflectance of 47.8percent, which was acceptable for processing, with 0 percent sugar ends. The clone'A00345-3LB' yielded 644 cwt/acre total, with 91 percent U.S. No. I grade, specificgravity 1.085 g cm3, and fry strip light reflectance of 44.5 percent.

133

30

25 -

20

15

10

5

0

Figure 1. Crop evapotranspiration (EL) and sprinkler irrigation applied (plus rain) topotato variety trials, Malheur Experiment Station, Oregon State University, Ontario, OR,2004.

0

-10

-20

Co

-30Cci)

0

00)

-50

-60

-70

Figure 2. Soil moisture data for sprinkler-irrigated potato variety trials, MalheurExperiment Station, Oregon State University, Ontario, OR, 2004.

134

Accumulated ETc

Accumulated irrigation+rain

0 N- 0 N- Co Co 0) Co 0) Co 0) CD£3 £3

CC) Co Co Co Co N- N- N- Co 0)

Co

£3C) C) 0)

Table 1. Yield, grade, and processing quality of potato entries grown in the Western Regional Early Harvest Trial at MalheurExperiment Station, Oregon State University, Ontario, OR, 2003.

U.S. No. i Average

Total Percent Total >12 6 - 12 4 - 6 U.S. Marketable <4 Cull Length/ Specific Fry color, SugarVariety yield No. 1 No. 1 oz oz oz No. 2 oz width gravity light ends

reflectance

cwt/acre % cwtlacre ratio g cm3 % %

RangerRusset 431 74 325 113 182 30 76 401 18 8 2.1 1.075 49.9 0.0

Russet Burbank 446 49 228 24 162 42 128 356 34 52 2.3 1.063 45.1 5.0

Russet Norkotah 290 88 256 42 159 55 8 264 22 2 1.9 1.063 47.7 2.5

Shepody 499 54 268 90 141 38 189 457 19 19 1.7 1.072 52.5 0.0

A92030-5 314 90 281 154 104 23 15 296 10 5 1.8 1.077 55.1 0.0

A92294-6 546 74 402 144 221 36 98 499 40 5 2.2 1.076 56.4 0.0

A9304-3 435 84 366 232 118 16 45 411 13 12 2.2 1.080 55.5 0.0

A9305-10 496 81 400 267 113 19 47 447 14 21 2.0 1.070 53.4 0.0

A93157-6LS 480 85 406 185 186 35 17 423 36 16 1.9 1.074 47.6 0.0

A95074-6 454 81 369 101 214 55 28 397 50 5 1.8 1.076 52.2 0.0

A95109-1 383 92 354 155 174 24 8 362 12 1 1.9 1.068 51.8 0.0

AC92009-4Ru 367 95 348 140 177 31 3 352 15 0 2.0 1.078 55.1 0.0

AC93026-9Ru 496 68 337 140 160 37 121 457 35 2 2.2 1.072 53.8 0.0

A096160-3 416 90 375 64 249 62 10 385 30 1 1.9 1.080 55.6 0.0

ATX91137-lRu 440 90 396 166 203 27 16 413 21 0 1.8 1.065 49.6 0.0

ATX92230-lRu 429 91 391 128 219 45 14 406 20 0 1.8 1.071 58.2 0.0

CO93001-llRu 415 76 318 19 203 96 30 348 59 0 1.7 1.064 49.9 0.0

CO94035-l5Ru 459 80 371 144 186 41 42 413 27 0 1.9 1.064 52.8 0.0

PA95AII-14 440 70 311 40 189 82 65 377 61 3 2.0 1.072 54.0 0.0

1C1675-lRu 473 85 405 109 229 67 27 432 33 6 1.9 1.081 54.7 0.0

Mean 436 80 345 123 179 43 49 395 28 8 1.9 1.072 52.6 0

LSD (0.05) 85 8 80 69 53 20 32 83 10 32 0.2 0.005 3.2 NSt

tNS= Not significant.

Table 2. Yield, grade, and processing quality of potato entries grown in the WesternExperiment Station, Oregon State University, Ontario, OR, 2003.

Regional Late Harvest Trial at Maiheur

TotalU.S. No. 1

Total >12 6 -12 4 - 6 U.S. Marketable <4 oz Cull Length! SpecificAverageFry color, SugarPercent

Variety

RangerRusset

yield

cwt/acre485

No.

%

66

1 No. 1 oz oz oz No. 2

cwt!acre319 178 113 28 147 466 16 3

width

ratio2.3

gravity

g cm31.084

lightreflectance

%

34.5

ends

%

18Russet Burbank 460 49 225 55 130 40 181 406 23 28 2.4 1.063 22.7 30Russet Norkotah 313 84 265 97 119 49 21 286 27 0 1.7 1.063 21.6 7Shepody 454 45 202 90 82 30 217 419 21 8 1.8 1.074 26.2 20A92030-5 342 83 285 171 85 28 39 323 17 0 1.8 1.077 42.2 0A92294-6 658 64 425 157 221 47 207 632 24 0 2.2 1.083 40.5 10A9304-3 422 74 312 174 114 23 85 397 11 13 2.2 1.080 38.2 0A9305-10 547 76 415 282 108 25 100 516 20 10 1.9 1.072 36.4 18A93157-6LS 567 76 435 241 143 51 87 522 34 1 2.0 1.088 46.2 0A95074-6 504 75 382 129 183 70 64 446 39 12 1.8 1.082 38.6 3A95109-1 404 84 339 172 141 27 50 389 12 0 1.9 1.078 30.9 8AC92009-4Ru 381 94 356 195 130 32 12 368 13 0 2.0 1.086 38.2 5AC93026-9Ru 466 61 282 152 97 33 145 427 37 2 2.2 1.074 29.9 23A096160-3 497 88 434 137 206 91 29 463 34 0 1.9 1.086 43.6 0ATX91137-lRu 477 92 437 213 176 48 18 455 17 5 1.9 1.069 25.8 15ATX92230-lRu 413 87 358 120 171 67 29 386 26 0 1.9 1.073 41.0 0C093001-llRu 373 78 292 40 161 91 36 328 46 0 1.7 1.065 31.2 10CO94035-l5Ru 459 73 344 151 151 42 80 423 27 0 1.8 1.071 33.7 13PA95AII-14 427 71 299 61 140 98 76 374 51 0 2.1 1.070 29.8 23TC1675-lRu 457 83 377 123 182 71 36 412 38 5 1.8 1.081 37.5 0Mean 455 75 339 147 143 49 83 422 27 4 2.0 1.076 34.0 10LSD (0.05) 66

tNS = Not significant.

10 68 51 44 20 43 60 14 13 0.2 0.008 4.1 NSt

Table 3. Yield, grade, and processing quality of potato entries grown in the Oregon Statewide Trial at Malheur Experiment Station,Oreqon State University, Ontario, OR, 2003.

TotalU.S. No. 1

U.S. Marketable <4 oz Cull Length! SpecificAverage

fry color, light SugarPercent Total >12 6-12 4-6Variety yield No. 1 oz oz oz No. 2 width gravity reflectance ends

gcm3 % %R. Burbank 389 60 234 29 139 66 102 336 45 8 2.2 1.060 29.4 30RangerR. 474 79 377 163 164 50 49 425 42 7 1.9 1.086 40.5 0R. Norkotah 282 84 237 41 142 54 4 241 39 2 2.0 1.060 30.7 0Umatilla R. 437 76 332 43 177 112 34 366 70 1 1.9 1.082 48.5 0

437 88 384 62 209 113 16 400 37 0 1.8 1.085 47.8 0399 83 331 93 173 65 29 360 36 3 2.0 1.077 51.1 0423 69 295 76 157 61 61 356 65 1 2.3 1.083 51.0 0

A096205-3 497 83 412 176 188 48 55 467 24 6 2.2 1.086 47.0 0398 96 380 238 117 25 9 389 9 0 1.7 1.093 48.0 0

A098133-4 356 79 284 47 163 74 16 300 55 1 1.6 1.084 38.7 0

A094006-4 381 91 347 104 183 59 4 351 28 3 1.9 1.069 27.7 3

A094007-1 424 88 373 91 224 59 17 389 35 0 2.2 1.067 48.3 0

A096047-2 308 84 258 10 130 118 2 259 49 0 1.5 1.088 42.1 0

A096073-2 467 84 389 121 216 53 20 410 40 18 2.0 1.069 30.6 28444 77 343 55 190 97 25 368 74 2 2.1 1.095 58.6 0

A098114-6 469 72 338 50 194 94 31 369 88 12 2.2 1.083 41.8 10

A098141-2 415 79 331 38 206 87 25 355 59 1 2.1 1.076 45.6 3

A099002-4 332 90 297 89 159 50 5 302 29 1 1.9 1.072 40.4 0

A099002-7 371 91 337 156 146 35 11 349 22 0 2.0 1.076 41.9 5

A099024-8 456 79 364 33 211 119 6 370 85 1 1.6 1.094 54.2 0

A099060-5 417 82 345 191 119 35 16 361 19 36 1.9 1.071 33.9 0

429 88 376 187 149 41 21 398 29 3 1.9 1.083 47.8 0

Umatilla4O7 474 71 338 57 181 100 53 391 80 3 1.9 1.084 43.6 0

Umatilla 418 422 78 329 34 175 121 29 358 63 1 2.0 1.079 45.2 3

Umatilla 432 429 78 332 45 181 106 42 374 52 3 2.0 1.078 46.2 0Umatilla 311 470 80 376 65 195 117 22 398 72 0 1.9 1.085 48.8 0

Norkotah 101 291 84 246 44 143 58 7 253 37 1 2.1 1.058 27.1 0Norkotah 206 288 88 253 57 136 60 4 257 30 0 2.0 1.059 25.7 5Norkotah 210 272 84 232 49 130 54 9 240 31 1 2.0 1.059 26.6 3

Mean 402 81 326 84 169 73 25 351 46 4.0 2.0 1.077 41.7 3LSD (0.05) 64 7 64 47 39 27 25 70 18 10 0.1 0.007 3.8 8

Table 4. Yield, grade, and processing quality of 11 early selections from the 131 entries in the Oregon Preliminarycompared to the 5 check entries, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

TotalU.S. No. 1

U.S. Marketable <4 Cull Length! SpecificAverage

fry color, light SugarPercent Total >12 6 - 12 4 - 6Variety yield No. I oz oz oz No. 2 oz width gravity reflectance ends

cwt/acre

Yield Trial,

R. Burbankcwtlacre

511%68 281 85 141 56 130 411 49 36

ratio2.5

g cm31.065

%28.9

%45

RangerR. 500 93 391 117 182 92 22 413 73 3 2.1 1.087 40.7 0Shepody 412 91 289 83 88 118 32 322 73 10 1.8 1.076 33.5 20Norkotah R. 494 97 449 323 80 47 9 459 28 2 2.0 1.059 26.3 5Umatilla R. 465 90 319 95 134 90 39 358 105 0 2.0 1.081 44.8 0A096305-3 386 99 339 88 188 64 2 341 44 0 2.4 1.080 44.3 0AO96365-2 472 94 395 198 131 66 26 420 52 0 1.9 1.080 32.3 5A096370-2 542 91 444 200 156 88 45 488 40 7 1.8 1.080 42.3 0A098123-2 604 100 547 269 200 78 0 547 57 0 1.7 1.093 58.4 0A098268-5 468 96 433 263 132 39 20 453 15 0 2.0 1.082 50.5 0AO98282-5 370 91 275 79 106 89 24 299 71 0 2.2 1.086 44.7 0A098307-6 538 99 480 238 164 78 8 487 44 0 2.3 1.098 52.1 0A099065-2 501 96 433 253 137 43 18 451 35 15 2.0 1.077 44.5 0A099081-1 370 99 334 240 69 24 6 340 17 13 2.0 1.087 51.7 0AO99108-5 583 96 511 349 120 42 18 530 41 0 2.0 1.081 45.3 0A099111-9 698 97 615 350 199 66 21 636 59 3 2.1 1.091 53.6 0Mean 427 96 355 150 143 63 15 371 512 2 1.9 1.078 40.4 6.1LSD (0.05) 180 11 172 170 88 53 39 180 44 NS 0.3 0.015 12.1 22

Table 5. Yield, grade, and processing quality of early selections from the Malheur Preliminary Trial (in bold) compared to severalcheck entries grown at Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

TotalU.S. No. 1

Total >12 6 - 12 4 - 6 U.S. Marketable <4 Cull Length! SpecificAverage

fry color, light SugarPercentVariety yield

cwt/acreNo.

%

I oz oz oz No. 2 oz widthratio

gravityg cm-3

reflectance%

ends%cwt!acre

Trial with 4 replicationsR. Burbank 389 60 234 29 139 66 102 336 45 6 2.2 1.060 29.4 30RangerR. 474 79 377 163 164 50 49 425 42 7 1.9 1.086 40.5 0

R. Norkotah 282 84 237 41 142 54 4 241 39 2 2.0 1.060 30.7 0

UmatillaR. 437 76 332 43 177 112 34 366 70 0 1.9 1.082 48.5 0Defender 407 79 325 91 172 62 36 361 46 0 1.7 1.089 42.1 3Gemstar 437 94 413 258 128 26 11 424 11 0 1.7 1.076 52.6 0A98345-1 506 68 335 154 117 63 112 446 55 1 1.8 1.086 42.9 0

A91814-2 622 85 527 55 285 188 18 546 74 2 1.1 1.087 50.3 0

Mean 444 78 347 104 165 78 46 393 48 2 1.8 1.078 42.1 4

LSD (0.05) 60 9 64 47 33 26 46 56 16 5 0.1 0.005 3.3 6

Trial with 2 replications

R.Burbank 511 68 281 85 141 56 130 411 49 36 2.5 1.065 28.9 45RangerR. 500 93 391 117 182 92 22 413 73 3 2.1 1.087 40.7 0

Norkotah R. 494 97 449 323 80 47 9 459 28 2 2.0 1.059 26.3 5

Umatilla R. 465 90 319 95 134 90 39 358 105 0 2.0 1.081 44.8 0

A99133-6 411 99 369 255 80 35 6 375 36 0 1.9 1.084 43.9 0

A96112-20 440 99 370 95 178 98 4 374 66 0 2.1 1.091 52.4 0

A99123-1 360 100 284 31 160 93 0 284 76 0 1.8 1.077 47.8 5

A96783-1O9LB 529 98 432 121 202 109 7 438 90 0 1.5 1.091 43.1 0

Meant 430 96 357 151 143 64 15 373 52 2 1.9 1.078 40.6 6.1

LSDt (0.05) 180 10 172 170 87 54 39 180 44 NSt 0.3 0.015 12.2 22

tstatjstjcs based on 135 entries.NS = Not significant.

Table 6. Yield, grade, and processing quality for 26 selectionsMalheur Experiment Station, Oreqon State University, 2004

from 84 potato clones entered in an Un replicated 8-Hill Trial at

TotalU.S. No. 1

Total >12 6 - 12 4 - 6 U.S. Marketable <4 Cull Length! SpecificAverage

fry color, light SugarPercentVariety yield No. 1 oz oz oz No. 2 oz width

ratio1.6

gravityg cm31.071

reflectance%

48.0

ends%0A99031-12

cwtlacre442

%95

cwtlacre420 347 61 13 8 428 14 0

A0012-2 552 88 487 251 140 96 7 494 57 0 1.7 1.071 50.2 0A0031-4 370 98 362 251 76 36 0 362 5 0 1.8 1.092 49.0 0A0036-2 487 95 462 307 129 26 9 470 16 0 1.8 1.077 45.8 0A0068-5 506 97 488 348 125 15 0 488 18 0 1.8 1.079 43.1 0A00138-1 403 95 382 230 102 50 0 382 21 0 1.4 1.074 40.3 0A00138-4 592 87 516 373 106 37 0 516 40 28 1.2 1.073 31.1 0A99074-9 545 82 448 180 208 60 27 475 70 0 1.6 1.073 34.7 0A99074-15 585 91 535 357 117 61 5 540 45 0 1.7 1.077 34.3 0A99134-1 329 99 326 268 50 8 0 326 3 0 2.1 1.079 43.1 0A97257-3 380 96 365 194 141 30 5 370 10 0 1.6 1.070 38.3 0A97320-1 487 95 465 287 101 76 0 465 22 0 1.7 1.074 35.9 0A97322-1 430 97 416 344 65 8 11 428 2 0 2.0 1.070 36.0 0C0A00295-1 533 88 467 348 75 45 0 467 40 0 1.6 1.088 39.5 10C0A00329-1 695 85 591 218 232 142 50 641 54 0 1.8 1.092 47.8 0C0A00369-4 659 93 616 229 261 125 3 619 40 0 1.9 1.064 34.0 0TXA000I1-1 381 95 361 298 63 0 0 361 20 0 2.0 1.074 21.2 0A00324-1 590 88 522 182 297 42 21 542 48 0 1.9 1.070 26.5 0A00345-3LB 644 91 588 347 121 119 2 590 49 0 1.6 1.085 44.5 0A00382-3LB 552 80 444 81 232 131 14 457 94 0 1.9 1.067 19.8 10A00487-22LB 690 81 560 124 323 113 8 568 122 0 1.7 1.076 37.8 10A00487-29LB 563 78 440 108 201 130 0 440 123 0 1.4 1.082 24.6 10A00538-52LB 574 74 424 59 220 144 12 436 138 0 1.7 1.079 39.6 0A00551-5OLB 536 93 500 308 124 68 0 500 36 0 1.8 1.071 40.9 10A00718-3 671 81 544 130 326 88 33 577 94 0 1.5 1.071 46.1 0A00645-1 581 89 518 358 106 54 40 558 23 0 1.9 1.065 28.4 10Overall Mean 451t 83t 375t 174t 12gt 72t 19t 394t 54t 2t

tMeans based on 84 entries.Means based on 26 entries.

TUBER BULKING RATE AND PROCESSING QUALITY OF EARLYPOTATO SELECTIONS

Clinton C. Shock, Eric P. Eldredge, and Monty D. SaundersMalheur Experiment Station


Introduction

Five potato cultivars 'Ranger Russet', 'Russet Burbank', 'Shepody', 'Umatilla Russet',and 'Wallowa Russet', and two early selections, 'A92294-6', and 'A93157-6LS' werecompared at six harvest dates in this trial. Ranger Russet, Russet Burbank, andShepody are currently grown in the Treasure Valley for processing and served as thecheck varieties. Umatilla Russet and Wallowa Russet are new releases from OregonState University (OSU) that have yield, grade, and processing quality generally superiorto Ranger Russet, Russet Burbank, and Shepody. The numbered clones haveperformed well in several previous variety trials at this location, including the WesternRegional Early Harvest Trial. The first objective of this study was to quantify the tuberbulking rate of potato cultivars that are currently grown, and some numbered clonesthat may soon be released, and to compare their suitability for production of earlyharvest potatoes for processing directly from the field. The second objective was todetermine which, if any, of these clones could continue to bulk tubers late in theseason.


The soil was Owyhee silt loam where the previous crop was winter wheat. The wheatstubble was flailed and the field was irrigated and disked. A soil test taken onSeptember 16, 2003 showed 37 lb nitrogen (N)/acre in the top 2 ft of soil, and 102 lbavailable phosphate (P205), 851 lb soluble potash (1<20), 29 lb sulfate (SO4), 1966 ppmcalcium (Ca), 463 ppm magnesium (Mg), 87 ppm sodium (Na), 1.6 ppm zinc (Zn), 18ppm iron (Fe), 4 ppm manganese (Mn), 0.7 ppm copper (Cu), 0.5 ppm boron (B),organic matter 3.5 percent, and pH 7.4 in the top foot of soil. Fall fertilizer was spread toapply 60 lb N/acre, 50 lb P2O5/acre, 80 lb K2O/acre, 57 lb sulfur (S)/acre, 8 lb Zn/acre, 5lb Cu/acre, and 1 lb B/acre. The field was ripped, Telone Il® soil fumigant was injectedat 25 gal/acre, and the field was bedded on 36-inch row spacing.

Potato seed was obtained from the OSU Potato Variety Development program atPowell Butte, and the USDA/Agricultural Research Service (ARS) potato program atAberdeen, Idaho. Seed of Ranger Russet was commercial certified seed from easternOregon, and seed of Umatilla Russet was commercial certified seed from centralOregon. Seed was cut by hand into approximately 2-oz pieces, treated with Tops-MZ®

141

plus Gaucho® seed treating dust, and counted into bags of 15 seed for each row of the2-row plots.

The potato clones were planted on April 13, with rows spaced 36 inches apart and

9-inch spacing between seed pieces in the row. The soil condition was excellent, withgood tilth and good soil moisture. The soil temperature at the seed piece depth,10-inches, was 56°F. The experiment was laid out in a split-plot design, with the harvestdates replicated four times as main plots within blocks and the varieties randomized ineach subplot. This was accomplished by planting the rows so that the six harvest datepasses through the four replicates would include all of the varieties.

A two-row per bed configuration was started at planting by leaving off the centerfurrowing shovel of the two-row planter. On May 6, the two-row beds were formed witha spike harrow pulling wide shovels to clean the furrows and form the shoulders of thebeds, and dragging a heavy chain to smooth and flatten the top of the bed. The tool baron back of the bed harrow also carried shanks and spools of drip tape to install a driptape at 2- to 3-inches depth directly above each potato row. The drip tape was 5/8-inchdiameter, with 5-mil wall thickness, 6-inch emitter spacing, 0.22 gal/mm/I 00-ft flow rate(T-tape, T-Systems International, San Diego, CA).

Soil water potential was measured with six Watermark sensors Model 200SS (IrrometerCo. Inc., Riverside, CA) installed in the potato row at the seed piece depth andconnected to an AM400 data logger (M.K. Hansen, East Wenatchee, WA) thatrecorded soil water potential every 8 hours. Water potential readings were alsorecorded manually from the data logger. Irrigations were scheduled to avoid soil waterpotential at the root zone dropping below -30 kPa. Crop evapotranspiration (EL) wasestimated by an automated AgriMet (U.S. Bureau of Reclamation, Boise, ID) stationlocated about 0.5 mile away on the Malheur Experiment Station.

Prowl® at 1 lb/acre plus Dual® at 2 lb/acre was applied on May 7, before any potatoplants had emerged, and was incorporated with the bed harrow. Matrix® herbicide wasapplied at 1.25 oz/acre on May 17, and was incorporated by 0.41 inch of rain on thenext day, followed by 0.89 inch additional rain through the end of May. Fungicideapplications to control early blight and prevent late blight infection started with an aerialapplication of Ridomil Gold® and Bravo® at 1.5 pint/acre on June 12. On June 25,Headline® fungicide was applied; on July 17, Topsin-M® fungicide plus liquid S with 1.5lb P205/acre and 0.2 lb Zn/acre was applied by aerial applicator. On August 8, Headlineplus 6 lb S/acre was applied to prevent two-spotted spider mite infestation and powderymildew infection. No fertilizer was applied to the field in the spring. Petiole tests weretaken every 2 weeks from June 11, and fertilizer was injected into the drip systemduring irrigation to supply the crop nutrient needs (Table 1).

Approximately 40 percent emergence was noted in the trial on May 12. On June 22, thefirst tubers were dug from one plot in each replicate. Tubers were sorted by weight andtubers in each weight category were counted and weighed. On July 13, tubers wereharvested from each replicate, and graded by the U.S. No. 1 and No. 2 for processing

142

standards, sorted by weight, and counted and weighed in each weight category.Specific gravity and length-to-width ratio were measured using a sample of 10 tubers,and fry color was measured on a sample of 20 tubers from each plot. The subsequentharvests, on August 3, August 24, September 14, and October 5, followed the sameprocedure as the second harvest.

Yield and quality results data were compared using analysis of variance (NumberCruncher Statistical Systems, Kaysville, UT). The tuber bulking rate over time wasevaluated using the equation: y = A+B / , where y is the tuber yield in cwt/acre,A, B, C, and D are the potato tuber bulking growth parameters, and t is the time in daysafter planting (DAP). A suitable value for the exponential variable D was found bypreliminary regressions on all the varieties. An average tuber initiation date for allclones was found by dividing the yield of the first harvest by the cwtlacre/day bulkingrate between the first and second harvests. The resulting tuber initiation (zero yield)date was 59.9 DAP.


The 2004 growing season was cool and rainy in April and May and lacked the usualprolonged heat in the summer months. The total amount of irrigation water appliedthrough the drip tape fell behind potato crop evapotranspiration (EL) through thegrowing season, with a total of 15.22 inches of applied irrigation plus rain, and a totalaccumulated of 27.60 inches (Fig. 1). The soil moisture sensors showed an earlyseason moisture deficit (Fig. 2). This was due to the early season water being onlysmall rainfall events and irrigation beginning June 4. Through the period from 56 to 113DAP, the sensors indicated wetter soil in the crop root zone than the optimum soil waterpotential for drip-irrigated potato of -30 kPa, despite the irrigations being less than theamount required to match ETC. The soil was intentionally allowed to become drier afterAugust 31, 140 DAP, to avoid rotting the tubers after vine senescence.

Because the crop root zone remained moist through the growing season, the plantswere not stressed and the fry color light reflectance was uniformly 40 percent or higher,except for the stem-end light reflectance of Russet Burbank from the final harvest(Table 2). Very few sugar ends were encountered in frying the samples. In the fourthharvest, 132 DAP, one sugar end was found in A93157-6LS out of 80 tubers fried, or1.25 percent. In the fifth harvest, 153 DAP, one sugar end was found in RussetBurbank. In the sixth harvest, 174 DAP, one sugar end was found in Russet Burbank,and one in Shepody.

Potato clones varied in yield and the size distribution of the tubers at the three latestharvest dates (Tables 2 and 3). Among the potatoes tested, A92294-6 was the heaviestbulking clone when harvested 132 DAP, with 466 cwtlacre total yield, and 90 percentU.S. No. 1 tubers. At 153 DAP, A93157-6LS with 512 cwt/acre and A92294-6 with 494cwt/acre were the highest in total yield.

143

Growers can only plant cultivars that have seed available and that have been acceptedby processing companies for contract production. Processors want specific gravityabove 1.080 to help assure quality products. Processors prefer tubers with alength/width ratio of about 1.8 to 2.0, so that French fry production is efficient. Atpresent, seed is available for Wallowa Russet, Umatilla Russet, Shepody, and RangerRusset. When the bulking rate of Wallowa Russet, Umatilla Russet, Shepody, andRanger Russet are compared at the three latest harvest dates, Wallowa Russet has ayield advantage, producing significantly more than the currently grown cultivars, exceptfor Ranger Russet at 153 DAP. Newer clones, which are not yet released and availableto growers, such as A92294-6 and A93157-6LS, had even higher productivity, with 568and 512 cwt/acre total yield, respectively, at 174 DAP (Table 2).

The tuber bulking rate for total yield, U.S. No. 1, and Marketable categories was plottedovertime and evaluated using the equation given above (Figs. 3-9). The U.S. No. 1category includes all smooth tubers, even undersized tubers less than 4 oz. TheMarketable category consists of the U.S. No. I and U.S. No. 2 tubers over 4 oz (Figs.3-9). Early in the growing season, from tuber initiation until tubers exceeded 4 oz, thetotal yield was the same as the U.S. No. I yield, and the bulking rate was generallylinear. Where the Marketable yield line crosses the U.S. No. 1 yield line indicates theDAP when U.S. No. 2 tubers outweighed the undersized tubers for each clone (Figs.3-9).

In previous work (Shock et al. 2002) we showed that early dying of potato vines inmid-August can be a major factor limiting potato productivity in Malheur County,because it limits the ability of tubers to continue to bulk late in the growing season. Inthe current work, the commercial varieties failed to have substantial marketable yieldincreases after mid-September, 153 DAP (Figs. 5-7, 9). The lack of increase inmarketable yield after 153 DAP was noted for Ranger Russet, Russet Burbank,Shepody, and UmatlIla Russet (Figs. 5-7, 9). In contrast, A92294-6, A93157-6LS, andWallowa Russet continued their upward trends in marketable yield to 174 DAP (Figs. 3,4, 8) finishing with 568, 512, and 482 cwt/acre, respectively. These clones deservespecial attention in future trials and possible tests for resistance to the componentpathogens of the early die disease syndrome.

Shepody and Ranger Russet are not especially suitable as early harvest cultivarsbased on yield. Other clones included in this trial bulked fairly early (Figs. 5-7, 9). Fromthe Western Regional Early Harvest potato variety trials in Ontario over the past fewyears, several other new clones have also shown promise (data not shown).

References

Shock, C.C., E.P. Eldredge, and L.D. Saunders. 2002. Tuber bulking rate of processingpotato clones in relation to planting date. Oregon State University AgriculturalExperiment Station, Special Report 1048:152-1 58.

144

Table 1. Fertilizer applied through the drip irrigation system in response to petiole testson potato clones and cultivars grown under drip irrigation, Malheur Experiment Station,Oregon State University, Ontario, OR, 2004.

N P205 K20 SO4 Zn Mn Cu Fe B

Date lb/acre6/8 15 20 20

6/15 20 10 10 0.257/3 20 107/4 20 0.25 0.25 0.1

7/5 20 107/15 20 20 20 0.05 0.05 0.05 0.1 0.027/17 1.5 0.27/27 20 108/8 18

total 115 51.5 60 48 0.5 0.55 0.05 0.1 0.12

145

Table 2. Tuber yield, grade, length-to-width ratio, specific gravity, and fry color of fivepotato clones and six potato varieties that grew until vine removal on August 24,September 13, or October 4, and subsequent harvest on August 24, September 14, orOctober 5 (Hrv 4, 5, 6), Malheur Experiment Station, Oregon State University, Ontario,OR, 2004.

Daysafter

planting

TotalTotal U.S.yield No. 1

PercentU.S.No. 1

Marketableyield Culls

Total 6-10 oz <4 ozLength!width

LightSpecific reflectancegravity stem bud Av.

Cultivar, clone Hrv DAP -cwt!acre- 0/ cwt!acre ratio gcm-3 o/

A92294-6 4 1325 153

6 174

466 420494 465

568 526

9094

92

444 196 23461 234 33

529 209 40

2.052.02

2.04

1.087 53 55 541.086 55 54 55

1.088 54 53 54A93157-6LS 4 132

5 153

6 174

422 403512 497

512 479

95

97

93

395 154 27

472 211 40

468 146 44

1.781.78

1.90

1.088 43 44 431.090 45 44 44

1.092 46 46 46

RangerR. 4 132

5 153

6 174

377 324400 363

438 394

86

91

90

362 159 15

376 160 24

406 134 31

1.94

1.89

2.02

1.086 45 49 471.087 46 47 47

1.090 50 50 50

R. Burbank 4 132

5 153

6 174

362 298356 292

419 324

83

82

77

339 152 23

331 172 25

385 157 34

2.07

2.02

2.07

1.073 45 42 441.074 40 44 42

1.071 37 44 41

Shepody 4 132

5 153

6 174

348 285344 288

413 338

81

84

82

334 115 15

331 136 13

385 113 28

1.55

1.63

1.66

1.076 47 51 491.079 52 48 50

1.078 46 45 46

WallowaR. 4 132

5 153

6 174

428 411

409 393

482 461

96

96

96

412 169 16

394 210 15

460 162 22

1.91

1.90

1.90

1.084 47 50 481.087 49 47 48

1.086 52 48 50

UmatillaR. 4 132

5 153

6 174

303 261

327 298

371 325

86

91

87

263 121 40282 143 44

306 141 65

1.92

1.97

2.02

1.081 49 52 51

1.079 50 48 49

1.082 50 49 50

Mean 4 132

5 153

6 174

387 343406 371

458 407

88

91

88

364 152 23

378 181 28

420 152 38

1.89

1.89

1.94

1.082 47 49 481.083 48 47 48

1.084 48 48 48

LSD (0.05) Hrv

CltrHrvXCltr

47.7 NS

23.8 27.1NS NS

NS

3.9

NS

NS NS 5.723.3 21.1 6.3

NS NS NS

NS

0.07

NS

NS NS NS NS

0.002 2.1 1.4 1.6

NS 3.7 2.5 2.7

146

Table 3. Tuber grade and size distribution of five potato clones and six potato varietiesthat grew until vine removal on August 24, September 13, or October 4, andsubsequent harvest on August 24, September 14, or October 5 (Hrv 4, 5, 6), MalheurExperiment Station, Oregon State University, Ontario, OR, 2004.

U.S. Number 1, oz sizes U.S. Number 2, oz sizes

4-6 6-8 8-10 10-12 12-16 >16 4-6 6-8 8-10 10-12 12-16 >16

Hrv DAP4 1325 153

6 174

4 1325 153

6 174

4 1325 153

6 174

4 1325 153

6 174

4 1325 153

6 174

4 1325 153

6 174

4 1325 153

6 174

Mean 4

5

6

56 93 83 65 80 21

59 128 97 64 58 26

76 100 99 75 83 54

80 78 72 62 61 2466 118 88 40 91 55

59 75 67 70 118 46

42 72 72 51 52 2247 74 77 50 52 40

42 65 62 62 70 63

72 88 53 37 26 2

76 94 58 22 15 4

56 73 64 50 39 10

30 48 51 39 53 5239 67 54 28 56 33

35 37 63 43 77 58

46 59 105 67 84 3542 98 106 46 62 26

48 72 85 80 112 44

80 65 41 21 14 2

56 76 58 33 28 4

64 70 58 43 28 4

7 13 7 6 7 6

3 4 4 4 7 7

6 5 4 8 9 9

2 4 1 0 4 8

1 1 3 0 3 6

3 3 1 5 7 14

6 13 4 4 10 16

3 4 6 7 7 9

5 4 4 6 6 19

3 8 3 6 22 21

5 15 5 12 14 10

5 9 11 10 18 40

4 5 11 10 13 184 6 9 8 13 13

6 6 8 11 22 20

2 2 3 1 8 01 2 4 0 5 2

2 4 2 3 7 3

10 11 4 2 9 42 5 4 5 3 9

5 7 7 3 10 8

Hrv NS 14.0 NS 12.5 16.0 9.2 1.3 NS 4.1 2.4 NS NS

CItr 14.2 15.6 12.5 11.8 13.3 15.5 NS 3.5 4.3 3.9 7.0 9.2

HrvXCItr NS NS NS NS 24.0 NS NS 6.1 NS NS NS NS

Cultivar, cloneA92294-6

A931 57-6LS

Ranger R.

R. Burbank

Shepody

Wallowa R.

Umatilla R.

LSD (0.05)

58 72 68 49 53 23 5 8 5 4 10 10

55 94 77 40 52 27 3 5 5 5 7 8

54 70 71 60 75 40 4 5 5 7 11 16

147

30

25

20

-c0C

15

10

5

0

Days after planting

Figure 1. Irrigation water applied through the growing season compared to cropevapotranspiration (ETa) estimated by an AgriMet weather station, Oregon StateUniversity, Malheur Experiment Station, Ontario, OR, 2004.

-10

-20

ca -30S

-40Ca>

a -50

U)

-60

0C/) -70

-80

-90

-100

Days after planting

Figure 2. Soil water potential (kPa) measured by Watermark sensors during theirrigation period of drip-irrigated potato clones, Oregon State University, MalheurExperiment Station, Ontario, OR, 2004.

148

U) C'l (D C/) 0 — CO U) N 0) (0 0 1-C/) U) CO 1- 0) 0) 0) 0 .- C'1 U) CO

C> N 0, (0 C, C p. —C> N cD p.> 0, (0 0, NN LU CD p.- CC Cc

U)

C-)CU

-oU)

>-

Figure 3. Tuber bulking over time for potato clone A92294-6, Oregon State University, Maiheur Experiment Station,Ontario, OR, 2004.

Total yield = -138 + 719 / (1+ 43.2.0.04t) R2 = 0.98U.S. No. One = -104 + 6491(1+ 50.70.04t) R2 = 0.97Marketable = -139 + 701 / (1 + 54.2 0.04t) R2 = 0.98

700

600

500

400

300

200

100

0

.

.A

48

Total

69 90 111

'•—'—'—'—'—'— Marketable

U.S. No. One

Days after planting, t

132 153 174

700

600

500

a)I—

400

300>-

200

100

048 132 153 174


Figure 4. Tuber bulking over time for potato clone A93157-6LS, Oregon State University, Maiheur Experiment Station,Ontario, OR, 2004.

Total yield = -132 + 691 / (1+ 48.9 o.o4t) R2 = 0.96U.S. No. One = -127 + 658/(1+ 48.3 0.04t) R2 = 0.96Marketable = -125 + 655 / (1+ 59.7 o.04t) R2 = 0.95

.4

$

..

SAI

.

TotalU.S. NJo. One

Marketable

69 90 111

ci)

C)C',

ci)

>-

Days after planting, tFigure 5. Tuber bulking over time for Ranger Russet, Oregon State University, Maiheur Experiment Station, Ontario, OR,2004.

Total yield = -170 + 617 / (1 + 28.0 o.04t) R2 = 0.98U.S. No. One = -166 + 562 I (1+ 25.0 0.04t) R2 = 0.97Marketable = -162+593/(1+ 35.30.04t) R2 0.97

700

600

500

400

300

200

100

0

....

A

A

.

I — — — — — —

A

Total— _ — _ _ _ _ _ _ _ — _

II — I — I — I — I — I —

48 69 90 111

U.S. No. One

Marketable

132 153 174

a)C)Co

0-o0)>-

Figure 6. Tuber bulking over time for Russet Burbank, Oregon State University, Maiheur Experiment Station, Ontario, OR,2004.

Total yield -482 + 888 / (1+ g.4o.o4t) R2 = 0.96U.S. No. One -553 + 875 / (1+ 6.40.04t) R2 = 0.93Marketable = -259+ 650 / (1+ 19.6 0.04t) R2 = 0.94

700

600

500

400

300

200

100

0

.

A

a a — — — . a a a — • — —

p

AA

48

TotalU.S. No. One

'——I—'—'—— Marketable

69 90 111 132 153


174

ci)

C)Co

-oU)

>-

Total yield -283 + 685 / (1+ 16.0 0.04t) R2 = 0.94U.S. No. One = -353 + 680 / (1+ 10.4 0.04t) R2 = 0.90Marketable = -239.+ 650 1(1+ 20.9 0.04t) R2 = 0.93

700

600

500

400

300

200

100

0

I

.

.A

— — — —_ S I — — — — — • —

A

AA

48 69 90 111

_. . — _ _ — _ — _..

II — I — I — I — I — I —

TotalU.S. No. One

Marketable

Days after planting, tFigure 7. Tuber bulking over time for Shepody, Oregon State University, Maiheur Experiment Station, Ontario, OR, 2004.

132 153 174

I—C)

ci)

>-


Figure 8. Tuber bulking over time for Wallowa Russet, Oregon State University, Maiheur Experiment Station, Ontario, OR,2004.

Total yield = -138 + 627 / (1+ 36.0 0.04t) R2 = 0.96U.S. No. One = -131 + 601 / (1+ 36.3 0.04t) R2 = 0.96Marketable = -144 + 628/(1+ 45.1 0.04t) R2 0.96

700

600

500

400

300

200

100

0

.4

.

I

48

Total

69 90 111

• — _ _ — _ _ — _ — _•

II — I — I — I — I — I —

U.S. No. One

Marketable

132 153 174

Total yield = -492 + 845/(1+ 7.9o.o4t) R2 = 0.95U.S. No. One = -589 + 900/(1+ 5.80.04t) R2 = 0.93Marketable = -198 + 512 / (1+ 20.1 0.04t) R2 = 0.95

Figure 9. Tuber bulking over time for Umatilla Russet,2004.

Oregon State University, Maiheur Experiment Station, Ontario, OR,

ci)

0

-oU)

>-

700

600

500

400

300

200

100

0

2*

.

48

A

—

U.S. No. One

'—'—'—u—'—'— Marketable

Total

69 90 111 132


153 174

PLANTING CONFIGURATION AND PLANT POPULATION EFFECTS ONDRIP-IRRIGATED UMATILLA RUSSET POTATO YIELD AND GRADE

Clinton C. Shock, Eric P. Eldredge, Andre B. Pereira,and Lamont D. Saunders

Malheur Experiment StationOregon State University

Ontario, OR, 2004

Introduction

Drip irrigation of potato for processing in the Treasure Valley of eastern Oregon andIdaho is not a standard production practice. However, drip irrigation could provideseveral advantages to growers, including no tailwater runoff from the field, the ability toapply fertilizer to the crop root zone, precise irrigation application, minimal leaching ofchemicals or salts to the groundwater, and reduced canopy moisture with reduced riskof fungal foliar diseases. Drip irrigation systems are costly to install and manage, andgrowers are reluctant to install them on fields where capital has already been spent toinstall furrow- or sprinkler-irrigation systems. To be profitable for potato production, dripirrigation should provide yield and quality above that obtainable with other irrigationmethods. This study was conducted to test modified planting configurations on thestandard 72-inch tractor wheel spacing used in Treasure Valley potato production, totest whether changes in the planting configuration could improve yield response to dripirrigation.

By placing two rows on a single bed, plants would be spread apart over the soil surface.They should not come immediately into competition with each other for sunlight duringJune, increasing yield potential. Spreading the plants across the bed could allow ahigher plant population, which might enhance yield and reduce the number of oversizepotatoes. Furthermore, the distribution of plants across the soil surface would providebetter soil shading during June, a factor that might result in better tuber quality.When potato seeds are planted directly in line with the drip tape, the roots and newtubers are directly in the most saturated part of the soil. By placing the drip tape offsetfrom the seed, roots and tubers would develop in a less saturated part of the potatobed, favoring tuber quality.

Methods

Both YearsThe treatments consisted of two populations, 18,150 and 24,200 plants per acre, witheach population planted in three configurations. Drip tapes were shanked into the bedson May 6. Configuration I was 2 rows 36 inches apart on a nominal 72-inch bed (72inches furrow to furrow) with a drip tape directly above each row of potatoes (Table 1).Configuration 2 was 2 rows 36 inches apart on a 72-inch bed with the drip tapes offset

156

7 inches to the inside of the bed from each potato row. Configuration 3 was 4 rows on a72-inch bed with 16 inches between the pairs of rows, and the paired rows 14 inchesapart, with the drip tape centered between the pairs of rows. Plants were staggered inthe paired rows. Plots were 20 ft long by 2 beds (12 ft) wide, replicated 4 times.

Irrigations were controlled by a CR10 data logger (Campbell Scientific, Logan, UT)connected to a multiplexer that provided connections for two Watermark (Irrometer Co.Inc., Riverside, CA) soil moisture sensors in each plot. The sensors were installed in aplant row at the seed piece depth. The data logger was connected through relays to a24VAC solenoid valve for each treatment. The drip tape on each set of 4 plots of atreatment was plumbed through 0.5-inch PVC pipe to 6 solenoid valves supplied withwater under constant pressure. The soil moisture sensors were read by the data loggerevery 3 hours. At midnight and noon the data logger calculated the average sensorreadings for each treatment. If the average soil water potential for a treatment wasbelow -30 kPa, the valve opened for 3 hours to apply a 0.2-inch irrigation. Cropevapotranspiration (EL) was estimated by an automated AgriMet (U.S. Bureau ofReclamation, Boise, ID) station located about 0.5 mile away on the Malheur ExperimentStation.

The vines were flailed from the potato plants on October 2, 2003, and on September21, 2004. The potatoes were dug on October 9, 2003 and on September 29, 2004. Thetubers from 15 ft of the center 2 rows of each 4-row plot were bagged and graded. Datawere statistically analyzed using the ANOVA procedure in NCSS (Number CruncherStatistical Systems, Kaysville, UT).

2003 TrialThe 2003 experiment was conducted on Owyhee silt loam, following winter wheat,where potato had not been planted for 3 years. In September 2002, after the wheatstubble had been chopped and irrigated, the field was disked. A soil test taken onSeptember 9, 2002 showed 18 ppm Nitrate (NO3), 18 ppm phosphorus (P), 306 ppmpotassium (K), organic matter 2.2 percent, and pH 7.6. Fall fertilizer was spread toapply 21 lb Nitrogen (N)Iacre, 100 lb phosphate (P205)/acre, 60 lb potash (K20)/acre,60 lb sulfur (S)/acre, 30 lb magnesium (Mg)/acre, 4 lb zinc (Zn)/acre, 2 lb copper(Cu)/acre, 1 lb manganese (Mn)/acre, and 1 lb boron (B)/acre. The field was deepripped, disked, and Telone Il® was applied at 25 gal/acre, and the soil was bedded on36-inch spacing. On April 4, 2003, Roundup® was applied at 1 qt/acre to control winterannual weeds and volunteer wheat.

Certified seed of 'Umatilla Russet' was cut by hand into 2-oz seed pieces and treatedwith Tops MZ + Gaucho® dust. On April 23 and 24, the cut seed was planted 8 inchesdeep using a custom-built potato plot planter. The planter used cups on chains drivenby a ground wheel, with interchangeable drive sprockets providing the adjustment ofseed spacing in the row. Four individual planter units could be slid to different positionson the frame so that two or four rows could be planted at various between-rowspacings. On April 28, the beds were shaped using a spike bed harrow pulling wide

157

shovels to maintain the wheel furrows and dragging a chain to pull soil into the center ofthe bed and smooth the top flat.

Prowl® at 1 lb/acre plus Dual® at 2 lb/acre was applied on May 1. On May 6 the driptape was installed in each plot using a pair of drip tape injectors and spools mounted ona tool bar and moved to the correct spacing for each treatment. The drip tape wasT-tape 0.22 gal/hour/I 00 ft, with 12-inch emitter spacing. Matrix® herbicide was appliedat 1.25 oz/acre on May 28. The first irrigation was applied on June 6. Bravo® plusRidomil Gold® was applied by aerial application on June 7 and again on June 25. Bravofungicide plus liquid sulfur was applied by aerial applicator on July 2, and again onAugust 8. Sulfur dust was applied by aerial applicator on July 20 at 40 lb S/acre.

2004 TrialThe procedures were similar for the 2004 trial. The soil was Owyhee silt loam where theprevious crop was winter wheat. The wheat stubble was flailed and the field wasirrigated and disked. A soil test taken on September 16, 2003 showed 37 lb N/acre inthe top 2 ft of soil, and 102 lb available P2O5, 851 lb soluble K20, 29 lb sulfate (SO4),1966 ppm Ca, 463 ppm Mg, 87 ppm Na, 1.6 ppm Zn, 18 ppm Fe, 4 ppm Mn, 0.7 ppmCu, 0.5 ppm B, organic matter 3.5 percent, and pH 7.4 in the top foot of soil. Fallfertilizer was spread to apply 60 lb N/acre, 50 lb P205/acre, 80 lb 1K20/acre, 57 lb S/acre,8 lb Zn/acre, 5 lb Cu/acre, and 1 lb B/acre. The field was ripped, Telone II soil fumigantwas injected at 25 gal/acre, and the field was bedded on 36-inch row spacing.

Potato seed of Umatilla Russet was commercial certified seed from central Oregon.Seed was cut by hand into approximately 2-oz pieces, treated with Tops MZ plusGaucho seed-treating dust. The potatoes in plots with four rows per bed were plantedon April 29, and the two-row beds were planted on April 30. On May 1, the beds wereformed with a spike harrow pulling wide shovels to clean the furrows and form theshoulders of the beds, and dragging a heavy chain to smooth and flatten the top of thebed. The drip tape was installed on May 5 and 6, at 2- to 3-inches depth. The drip tapewas 5/8-inch diameter, with 5-mil wall thickness, 6-inch emitter spacing, 0.22gal/mm/lOU ft flow rate (1-tape, 1-Systems International, San Diego, CA). Irrigationsbegan on June 16.

Prowl at 1 lb/acre plus Dual at 2 lb/acre was applied on May 7, 2004 before any potatoplants had emerged, and was incorporated with the bed harrow. Matrix herbicide wasapplied at 1.25 oz/acre on May 17, and was incorporated by 0.41 inch of rain on thenext day, followed by 0.89 inch of additional rain through the end of May. Fungicideapplications to control early blight and prevent late blight infection started with an aerialapplication of Ridomil Gold and Bravo at 1.5 pint/acre on June 12. On June 25,Headline® fungicide was applied, on July 17, Topsin-M fungicide plus liquid sulfur with1.5 lb P2O5/acre and 0.2 lb Zn/acre was applied by aerial applicator. On August 8,Headline pIus 6 lb S/acre was applied to prevent two-spotted spider mite infestation andpowdery mildew infection. No fertilizer was applied to the field in the spring. Petioletests were taken every 2 weeks from June 11, and fertilizer was injected into the dripsystem during irrigation to supply the crop nutrient needs.

158

Fertilizer solution was injected into the drip system in response to bi-weekly petioletests. The total fertilizer applied from June 19 to August 14, both through the dripsystem and by aerial application, was 108 lb N/acre, 28 lb P205/acre, 12 lb K20/acre, 14lb S04/acre, 40 lb S/acre, 0.03 lb Ca/acre, 0.5 lb Mg/acre, 0.61 lb Zn/acre, 1.15 lbMn/acre, 0.69 lb Cu/acre, 0.06 lb Fe/acre, and 0.01 lb B/acre.


2003 ResultsIn 2003, the low-population (18,150 plants/acre), 36-inch hills with drip tapeconfiguration yielded 556 cwt/acre, significantly more than the 470 cwt/acre total yield inthe high-population (24,200 plants/acre), 36-inch hills with drip tape configuration(Table 2).

For the marketable yield category, comprised of the U.S. No. 1 and No. 2 tubers over 4oz, there was a significant difference between the high and low plant population on thehills with drip tape configuration. The average marketable yield was higher with the lowplant population, and there was a significant interaction between population andconfiguration because the marketable yield of the standard configuration at the highplant population was 333 cwt/acre, which was significantly lower than all othertreatments.

There were no significant differences in percentage of U.S. No. 1 tubers among thetreatments. The overall average percentage of U.S. No. 1 tubers, 66 percent, was lowerthan usual for Umatilla Russet at this location. Percentage U.S. No. 1 tubers rangedfrom 70 percent for the staggered double row (configuration 3) at the low plantpopulation, to 63 percent for the 2 rows per bed with the drip tapes offset 7 inches(configuration 2) at the high population.

The high plant population produced significantly more small, 4- to 6-oz, U.S. No. Itubers, and undersized tubers. There were no significant differences in yield of 6- to12-oz U.S. No. 1 tubers. The high plant population produced a lower 12- to 16-oz andover 16-oz U.S. No. 1 yield. Total U.S. No. 1 yield was significantly higher at the lowplant population with configuration 1.

The yield of U.S. No. 2 tubers was significantly greater with the low plant population.The high plant population standard configuration produced the lowest U.S. No. 2 yield,but that treatment also produced the most undersize tubers of less than 4 oz.

2004 ResultsIn 2004, there was a significant interaction between population and configuration forpercentage of U.S. No. I tubers. There was a higher percentage of U.S. No. 1 in thelow population with 2 rows of potato plants on a 72-inch bed with 2 drip tapes offset 7inches inside the row, compared to the 2 rows with the drip tape above the row at thelow population and 4 rows in a staggered planting with tapes between pairs of rows at

159

the high population (Table 3). This interaction in production of U.S. No. 1 tubers alsowas seen in the total U.S. No. 1 production in 2004.

Both YearsThe averaged data from 2003 and 2004 showed significantly higher total yield forconfiguration 3 at the high population (Table 4). The high population producedsignificantly more 4- to 6-oz tubers, and there was a significant year by populationinteraction. The lowest yield of U.S. No. 2 tubers was produced by the high populationin two rows per bed with drip tape above the row (configuration 1).

The soil water remained adequate all season, since the soil water potential remained inthe ideal range for all treatments (Fig. 1).

The average water applied by the drip-irrigation systems is one of the interestingaspects of this trial. The total amount of water applied by the drip systems plus rainfallaveraged only 15.76 inches, 66.3 percent of the estimated potato evapotranspiration(23.78 inches) from May 25 to September 3 of 2004 (Fig. 2). This result suggests thatdrip irrigation is a very efficient method for applying limited amounts of water for potatoproduction.

160

a-

a)4-00.C)4-

0Cl)

Figure 1. Average soil water potential of six different drip-irrigation treatments forpotato, 2004, Malheur Experiment Station, Oregon State University, Ontario, OR.

30 50 70 90 110 130

Days after planting

Treat I

Treat 2

Treat 3

- Treat 4

Treat 5

Treat 6

ETc

Figure 2. Cumulative irrigation water plus rainfall for six different drip-irrigationtreatments for potato compared with the accumulated potato evapotranspiration fromMay 25 through September 3, 2004, Malheur Experiment Station, Oregon StateUniversity, Ontario, OR.

161

0

-10

-20

-30

-40

-50

Treat I

Treat 2

Treat 3

Treat 4

Treat 5

Treat 6

40 50 60 70 80 90 100 110 120 130

Days after planting

U)C).=C.)

C.)I-LU

a)4-CC

VC)

4-.CC

E

C)C.)

25

20

15

10

5

0

Table 1. Relationship of planting configuration treatments in the planting configurationtrial to a common potato production planting configuration, Malheur Experiment Station,Oregon State University, Ontario, OR, 2003 and 2004.

Rows and row widths Plant population Drip tapeConfiguration placement relative

to plant rowper 36-inch bed Plants/acre

Common grower 1 row 18,150 nonepractice

Treatments in this per 72-inch bedtrial

Treatment 1 2 rows 18,150 in row

Treatment 2 2 rows 18,150 offset 7 inchesfrom row

Treatment 3 2 double rows 18,150 between doublerows

Treatment 4 2 rows 24,200 in row

Treatment 5 2 rows 24,200 offset 7 inchesfrom row

Treatment 6 2 double rows 24,200 between doublerows

162

Table 2. Yield and grade of Umatilla Russet grown at two plant populations and three planting configurations with respectto the drip tape, Malheur Experiment Station, Oregon State University, Ontario, OR, 2003

. U.S.2003

Total MarketableU.S. No. 1 yield over 4 oz No. 2 Undersized

4 to 6 6 to 12 over 12 over 4Treatment

Population Configuration18,150 1

yield yieldcwt/acre

556.4 469.9

Percent%

67.9

oz oz oz Total oz under 4 ozcwt/acre

77.6 191.8 107.7 377.1 92.8 86.418,150 2 516.7 447.4 65.4 70.3 178.4 90.6 339.2 108.2 69.218,150 3 516.0 459.3 70.4 68.9 201.9 91.1 361.9 97.4 56.7Mean 529.7 458.9 67.9 72.3 190.7 96.5 359.4 99.5 70.8

24,200 1 469.7 333.3 63.4 113.3 155.1 29.2 297.6 35.7 136.424,200 2 530.9 424.8 62.7 91.8 169.3 74.5 335.6 89.2 106.124,200 3 533.0 447.2 67.0 98.4 200.7 58.5 357.6 89.6 85.8Mean 511.2 401.8 64.4 101.1 175.0 54.1 330.3 71.5 109.4

Average 1 513.0 401.6 65.6 95.4 173.4 68.5 337.3 64.3 111.4Average 2 523.8 436.1 64.1 81.0 173.8 82.5 337.4 98.7 87.7Average 3 524.5 453.3 68.7 83.7 201.3 74.8 359.8 93.5 71.3Overall mean 520.4 430.3 66.1 86.7 182.8 75.3 344.8 85.5 90.1

LSD (0.05) Population 22.5 31.8 NS 13.5 NS 13.4 13.3 19.2 22.7LSD (0.05) Configuration NS 39 NS 16.6 NS NS NS 23.2 27.8LSD (0.05) P x C 39 55.1 NS NS NS NS NS NS NSLSD (0.05) Replicate NS 45 NS NS 40.6 NS NS NS 32

Table 3. Yield and grade of Umatilla Russet grown at two plato the drip tape, Malheur Experiment Station, Oregon State

nt populations and three planting configurations with respectUniversity, Ontario, OR, 2004.

U.S.2004

Total MarketableU.S. No. 1 yield over 4 oz No. 2 Undersized

4 to 6 6 to 12 over 12 over 4Treatment yield yield

Population Configuration cwt/acrePercent oz oz oz Total oz under 4 oz

% cwt/acre18,150 1 344.4 254.9 55.0 54.5 124.2 12.7 191.5 63.4 86.818,150 2 384.7 325.8 75.2 59.7 178.6 52.9 291.2 34.6 58.918,150 3 373.5 281.5 63.5 84.5 130.5 20.2 235.2 46.3 90.4Mean 367.5 287.4 64.5 66.2 144.5 28.6 239.3 48.1 78.7

24,200 1 402.1 331.2 71.1 59.5 151.5 77.1 288.1 43.2 70.824,200 2 357.4 277.1 62.7 59.7 143.1 22.9 225.6 51.5 75.424,200 3 380.5 267.0 51.9 61.6 117.9 20.2 199.6 67.4 113.2Mean 380.0 291.7 61.9 60.3 137.5 40.0 237.8 54.0 86.4

Average 1 373.3 293.1 63.1 57.0 137.9 44.9 239.8 53.3 78.8Average 2 371.0 301.4 68.9 59.7 160.8 37.9 258.4 43.1 67.1Average 3 377.0 274.2 57.7 73.0 124.2 20.2 217.4 56.8 101.8Overall mean 373.8 289.6 63.2 63.2 141.0 34.3 238.5 51.1 82.6

LSD (0.05) Population NS NS NS NS NS NS NS NS NSLSD (0.05) Configuration NS NS NS NS NS NS NS NS NSLSD (0.05) P x C NS NS 16.6 NS NS NS 88.7 NS NSLSD (0.05) Replicate NS NS NS NS NS NS NS NS NS

Table 4. Yield and grade of Umatilla Russet grown at two plant populations and three planting configurations with respectto the drip tape, averaged over two years, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

2003 and 2004 Averaged

TreatmentPopulation Configuration18,150 1

18,150 218,150 3Mean

Total Marketableyield yield

cwt/acre450.4 362.4450.7 386.6444.7 370.4448.6 373.1

U.S. No.U.S. No. I yield over 4 oz 2 Undersized

Percentpercent

61.470.367.066.2

6 to 12 over 12 over 44 to 6 oz oz oz Total oz under 4 oz

cwt/acre66.1 158.0 60.2 284.3 78.1 86.665.0 178.5 71.7 315.2 71.4 64.176.7 166.2 55.7 298.6 71.8 73.669.2 167.6 62.5 299.3 73.8 74.8

24,200 1

24,200 224,200 3Mean

435.9 332.3444.1 350.9456.8 357.1445.6 346.8

67.362.759.563.1

86.4 153.3 53.1 292.8 39.4 103.675.7 156.2 48.7 280.6 70.3 90.780.0 159.3 39.3 278.6 78.5 99.580.7 156.2 47.0 284.0 62.8 97.9

Average 1

Average 2Average 3Overall mean

443.1 347.3447.4 368.8450.7 363.7447.1 359.9

64.366.563.264.7

76.2 155.6 56.7 288.5 58.8 95.170.3 167.3 60.2 297.9 70.9 77.478.4 162.7 47.5 288.6 75.2 86.575.0 161.9 54.8 291.7 68.3 86.3

LSD (0.05) YearLSD (0.05) PopulationLSD (0.05) YearxPopulationLSD (0.05) ConfigurationLSD (0.05) YearxConfigurationLSD (0.05) Population xConfig.

19.34 32.10NStNS (6%)

NS NSNS NS

NS NS

NSNSNS

NS(6%)

(8%)

5.89 NS 19.17 36.72 6.74 NS8.81 NS (9%) NS (8%) NS

12.46 NS 24.88 NS 17.56 (8%)

NS NS NS NS (9%) NS15.26 NS NS NS 21.51 30.01

NS NS NS NS 21.51 NS

tNot Significant at alpha = 0.05.Becomes significant at this alpha level.

A SINGLE EPISODE OF WATER STRESS REDUCES THE YIELD ANDGRADE OF RANGER RUSSET AND UMATILLA RUSSET POTATO

Andre B. Pereira, Clinton C. Shock, Eric P. Eldredge, and Lamont D. SaundersMalheur Experiment Station


Introduction

Deficit irrigation is a strategy where crops are allowed to sustain some degree ofwater deficit in order to reduce costs and potentially increase revenues. Englishand Raja (1996) described three deficit irrigation case studies where thereductions in irrigation costs are greater than the reductions in revenue due toreduced yields. In these case studies deficit irrigation can lead, in principle, toincreased profits when water supplies are limited.

Deficit irrigation has been used successfully with a number of crops. Shock et al.(1998) reported that deficit irrigation of potatoes could be difficult to managebecause reductions in tuber yield and quality can result from even brief periodsof water stress. However, in some circumstances potatoes can tolerate limiteddeficit irrigation before tuber set without significant reductions in tuber externaland internal quality.

It is generally recognized that some potato varieties are more drought tolerantthan others, that is, they give higher yields of tubers in dry years than othervarieties (Joyce et al. 1979). Nevertheless, there is not enough information onthe effects of slight or moderate water stress on yield of different varieties ofpotato. The adoption of new potato cultivars by growers and processors makes itdesirable to reexamine deficit irrigation, particularly during tuber development.

The objectives of this study were to 1) determine 'Umatilla Russet' and 'RangerRusset' potato responses to a single episode of water stress during tuberbulking, and 2) evaluate the potential for deficit irrigation to improve economicefficiency of potato production in the Treasure Valley under a sprinkler-irrigationsystem.


Two potato varieties (Umatilla Russet and Ranger Russet) were grown undersprinkler irrigation on Owyhee silt loam, where winter wheat was the previouscrop in a potato, wheat, corn, wheat, and potato rotation. The wheat stubble wasflailed and the field was irrigated and disked. A soil test taken on September 16,2003 showed 37 lb nitrogen (N)/acre in the top 2 ft of soil, and 102 lb available

166

phosphate (P205), 851 lb soluble potash (K20), 29 lb sulfate (SO4), 1966 ppmcalcium (Ca), 463 ppm magnesium (Mg), 87 ppm sodium (Na), 1.6 ppm zinc(Zn), 18 ppm iron (Fe), 4 ppm manganese (Mn), 0.7 ppm copper (Cu), 0.5 ppmboron (B), 3.5 percent organic matter, and pH 7.4 in the top foot of soil. Fertilizerwas spread in the fall to apply 60 lb N/acre, 50 lb P205/acre, 80 lb 1K20/acre, 57lb sulfer (S)Iacre, 8 lb Zn/acre, 5 lb Cu/acre, and 1 lb B/acre. The field wasripped, Telone Il® soil fumigant was injected at 25 gal/acre, and the field wasbedded on 36-inch row spacing.

Seed of the 2 varieties was hand cut into 2-oz seed pieces and treated withTops-MZ+ Gaucho® dust 1-2 weeks before planting and placed in storage tosuberize. On March 22 the field was cultivated with a Lilliston rolling cultivator toreshape the hills and to control winter annual weeds and volunteer wheat. OnApril 2 a soil sample was taken that showed 43 lb N/acre in the top two feet ofsoil, 83 lb available P205, 688 lb soluble K20, 26 lb SO4, 1,835 ppm Ca, 353 ppmMg, 69 ppm Na, 1.1 ppm Zn, 5 ppm Fe, I ppm Mn, 0.4 ppm Cu, 1.2 ppm B, pH7.4, and 3.0 percent organic matter in the top foot of soil.

Potato seed pieces were planted using a 2-row cup planter with 9-inch seedspacing in 36-inch rows. Umatilla Russet was planted on April 19 and RangerRusset was planted on April 26. After planting, hills were formed over the rowswith a Lilliston rolling cultivator. Prowl® at 1 lb/acre plus Dual® at 2 lb/acreherbicide was applied as a tank mix for weed control on May 7 and wasincorporated with the Lilliston. Matrix® herbicide was applied at 1.25 oz/acre onMay 17 and was incorporated by 0.41 inch of rain on the next day, followed by0.89-inch additional rain through the end of May 2004.

Under non-water stress conditions irrigation was applied 16 times from June 4 toAugust 30, with scheduling based on soil water potential (Fig. 1). The averagereadings of 6 Watermark soil moisture sensors model 200 SS (Irrometer Co.Inc., Riverside, CA) were monitored every 8 hours by a Hansen model AM400datalogger (M. K. Hansen Co., East Wenatchee, WA). Sensors were installed inthe potato row at the seedpiece depth, 10 inches from the top of the hill. TheAM400 unit was read daily through the summer to establish when to irrigate, withthe objective to apply water before the average soil moisture in the potato rootzone at the seedpiece depth exceeded -60 kPa (Fig. 2). Water applied wasestimated by recording the sprinkler set duration at 55 psi, and using the nominalsprinkler head output. Crop evapotranspiration (ETa) was estimated by the U.S.Bureau of Reclamation based on data from an AgriMet weather station on theMalheur Experiment Station.

For the water stressed treatment, a single irrigation was skipped on June 28during tuber bulking (Fig. 1). Eight rain shelters 21 ft long and 10 ft wide weremade from clear polyethylene sheets stretched over PVC pipe. These rainshelters were used to prevent sprinkler irrigation on four plots of Umatilla Russetand four plots of Ranger Russet. The area of each plot was 3 potato plant-rows

167

spaced 3 ft apart, 21 ft long, with only the center 15 ft of the middle rowharvested. The statistical design was a randomized complete-block design withfour replicates. After the 5-hour, 1 .5-inch irrigation, the plastic sheets wereremoved from the PVC frames.

Fungicide applications to control early blight and prevent late blight infectionstarted with an aerial application of Ridomil Gold® and Bravo® at 1.5 pint/acre onJune 12. On June 25, Headline® fungicide was applied; on July 17, Topsin-M®fungicide plus liquid sulfur with 1.5 lb P205/acre and 0.2 lb Zn/acre was appliedby aerial applicator. On August 8, Headline plus 6 lb S/acre was applied toprevent two-spotted spider mite infestation and powdery mildew infection.

Petiole tests were taken every 2 weeks from June 14, and fertilizer was injectedinto the sprinkler line during irrigation to supply the crop nutrient needs. A total of103 lb N/acre, 44 lb P2O5/acre, 140 lb K20/acre, 100 lb SO4/acre, 0.3 lb Mn/acre,5 lb Mg/acre, 0.1 lb Cu/acre, 0.1 lb Fe/acre, and 0.5 lb B/acre were applied.

Vines were flailed on September 21 and Umatilla Russet and Ranger Russettubers were dug on October 5 and 6 with a two-row digger that laid the tubersback onto the soil in each row. Visual evaluations included observations ofdesirable traits, such as a high yield of large, smooth, uniformly shaped andsized, oblong to long, attractively russetted tubers, with shallow eyes evenlydistributed over the tuber length.

Tubers from 15 ft of the middle row of the 3-row plot were picked up. Tuberswere placed into burlap sacks and hauled to a barn where they were kept undertarps until grading. Tubers were graded and a 20-tuber sample from each plotwas placed into storage. The storage was kept near 90 percent relative humidityand the temperature was gradually reduced to 45°F. Tubers were removed fromstorage December 7 and evaluated for tuber quality traits, specific gravity, andfry color. Specific gravity was measured using the weight-in-air, weight-in-watermethod. Ten tubers per plot were cut lengthwise and the center slices were friedfor 3.5 mm in 375°F soybean oil. Percent light reflectance was measured on thestem and bud ends of each slice using a Photovolt Reflectance Meter model 577(Seradyn, Inc., Indianapolis, IN) with a green tristimulus filter, calibrated to read 0percent light reflectance on the black standard cup and 73.6 percent lightreflectance on the white porcelain standard plate.

Data were analyzed with the General Linear Models analysis of varianceprocedure in NCSS (Number Cruncher Statistical Systems, Kaysville, UT) usingthe Fisher's Protected LSD means separation t-test at the 95 percent confidencelevel.

168


Precipitation for May 1 through September 30 was 2.55 inches and the cropevapotranspiration (ETa) totaled 26.19 inches. The potato plants received 22.15inches of irrigation plus precipitation throughout the full growing season, or 84.6percent of (Fig. 1). The step increases in the irrigation plus rainfall curve(control) show the 16 sprinkler irrigations applied during the growing season. Forthe water stress treatment, 15 irrigation episodes were applied, with a singledeficit imposed on June 28 as pointed out by the arrow in Figure 1. The previousirrigation was on June 22 and the first irrigation following stress was on July 4.Rainfall during this time interval was 0.07 inch on June 24 and 0.03 inch on June30.

The trend of soil moisture during the growing season is presented in Figure 2.The data do not show the individual irrigations because the water did not alwayspenetrate the soil to the sensors. The irrigation plus rainfall was less than forthe growing season, and the sensor data show that average root zone soil waterpotential became drier than -60 kPa at least four times during the growingseason.

Soil water potential at the seedpiece depth was allowed to become drier than -60kPa at the end of the growing season, due to the risk of tuber decay in this field.Frequent sprinkler irrigations of short duration were applied, as shown in Figure2. This was necessary to avoid swollen lenticels and the associated possibility ofrotting the tubers of the early maturity potato varieties planted in the same field,while continuing to apply a portion of the requirement for the late maturingentries in shallow moisture increments.

Although mean total yield for both cultivars was not influenced by watertreatments tested in this preliminary trial, marketable yield and total yield of U.S.No. 1 tubers were significantly affected by a single episode of water stress duringtuber bulking (Table 1). Deficit irrigation substantially reduced the percentage ofU.S. No. 1 and over-i 2-oz tubers, with Ranger Russet showing morepronounced response to water stress than Umatilla Russet.

In this preliminary trial, Umatilla Russet responded positively to applied water fortotal yield and was the most productive cultivar in total yield, besides thenon-significant differences among treatments; this agrees with the resultsobtained by Shock et al. (2003). However, Ranger Russet showed the highesttotal U.S. No. I and marketable yields under a non-limiting water supply.

Production of marketable tubers for processing (which comprises total U.S. No. 1plus U.S. No. 2 grades) was significantly affected by a single missed irrigation forboth potato cultivars. A single episode of water stress during tuber bulkingbrought about a reduction of 4.5 percent and 26.0 percent on marketable yield ofUmatilla Russet and Ranger Russet, respectively.

169

Shock et al. (2003) reported that well-watered potato subjected to irrigationdeficits during tuber bulking responded with reduced specific gravity. Althoughnonsignificant differences were found between cultivars under both irrigationtreatments for specific gravity in this preliminary study, a slight tendency towardreduced specific gravity was observed for Ranger Russet due to a single episodeof water stress during tuber bulking. The specific gravity ranged from 1.079 to1.084 g with Ranger Russet showing mean values above 1.080 g cm3when water was applied at a rate as close as possible to EL, a desirable levelfor processing into frozen potato products.

Length/width ratio was significantly affected by irrigation deficit, with a reductionof about 9 percent for the Ranger Russet potato cultivar.

Acknowledgements

We would like to thank Conselho de Desenvolvimento Cientifico e Tecnologico(CNPq) of Brazil for providing a Post-Doctoral scholarship and also for thesupport from Oregon State University that enabled this work.

References

English, M., and SN. Raja. 1996. Perspectives on deficit irrigation. AgriculturalWater Management 32:1-1 4.

Joyce, R., A. Steckel, and D. Gray. 1979. Drought tolerance in potatoes. J.Agric. Sci. (Cambridge) 92:375-381.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 1998. Potato yield and qualityresponse to deficit irrigation. HortScience 33:655-659.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2003. 'Umatilla Russet' and'Russet Legend' potato yield and quality response to irrigation. HortScience38:1117-1 121.

170

1..a)

Cs

0Ce

0C

ETC Check 1 Stress

25

20

15

10

5

0140 160 180 200 220 240 260

Day of the year

Figure 1. Crop evapotranspiration (ETa), sprinkler irrigation applied plus rainfall(control), and a single episode of water stress (arrow) during tuber bulking ofRanger Russet and Umatilla Russet potato, Malheur Experiment Station, OregonState University, Ontario, OR, 2004.

230 . -- ——

— —. ——.— — •

•70

•

Figure 2. Soil moisture data over time for a sprinkler-irrigated potato trial,Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

171

Table 1. Mean yield and grade of Ranger Russet and Umatilla Russetsprinkler-stressed potato trial, Maiheur Experiment Station, Oregon StateUniversity, Ontario, OR, 2004.

Variety + irrigation Yield Yield Yield Yield Yield Yieldtreatment <4oz 4-6oz 6-l2oz >l2oz No. 2 cull

cwt/acreUmatilla check 69.4 55.3 120.4 35.3 69.7 21.4Umatilla stress 84.6 50.2 107.7 15.9 94.4 6.1Ranger check 45.5 65.8 96.8 90.1 66.8 0.0Rangerstress 84.5 80.1 109.2 7.5 40.0 1.1LSD (0.05) var. NS 14.5 NS 17.2 17.6 NSLSD (0.05) stress 17.1 NS NS 17.2 NS NSLSD (0.05) var. x stress NS NS NS 24.3 24.9 NS

Variety + irrigation Rotten No. 1 Marketable Total Specific Lengthtreatment tubers yield yield yield gravity /width

cwtlacre gcm3 ratioUmatilla check 1.8 211.0 280.7 373.4 1.079 2.19Umatilla stress 0.7 173.8 268.2 359.7 1.079 2.15Ranger check 0.8 252.7 319.5 365.8 1.084 2.16Rangerstress 1.5 196.8 236.7 323.9 1.080 1.96LSD (0.05) var. NS 23.2 NS NS NS NSLSD (0.05) stress NS 23.2 37.9 NS NS 0.11LSD (0.05) var. x NS NS NS NS NS NSstressNS = Not significant.

172

IRRIGATION SYSTEM COMPARISON FOR THE PRODUCTION OF RANGERRUSSET AND UMATILLA RUSSET POTATO

Clinton C. Shock, Eric P. Eldredge, Andre B. Pereira,and Lamont D. Saunders


Ontario, OR, 2004

Introduction

Potato is most often produced using sprinkler irrigation. Over the past 5 years variousdrip-irrigation layouts have been tested for potato production at the Malheur ExperimentStation. One option for drip irrigation that we have not tested in recent years would beto plant potatoes in exactly the same way that potatoes are grown under sprinkler andfurrow irrigation in 36-inch beds. Since we were studying drip-irrigation designs, anadditional treatment was added to every replicate where potato was grown inconventional beds. Plots of all treatments were lengthened in 2004 so that both'Umatilla Russet' and 'Ranger Russet' could be grown in each planting configuration. Inaddition, sprinkler-irrigated Umatilla Russet and Ranger Russet potatoes were grownalongside the drip irrigation experiment. This allowed a comparison of sprinklerirrigation, drip with conventional 36-inch hilled beds, and drip irrigation with various flatbed configurations.

Methods

Umatilla Russet and Ranger Russet were grown using sprinkler irrigation and 4 dripirrigation layouts at 18,150 plants/acre (Table 1). The drip-irrigation cultural practicesare described in Shock et al. "Planting configuration and plant population effects ondrip-irrigated Umatilla Russet potato yield and grade" found in this report. Thesprinkler-irrigation cultural practices are described in Pereira et at. "A single episode ofwater stress reduces the yield and grade of Ranger Russet and Umatilla Russet potato"also found in this report.

Drip tapes were shanked into the beds on May 6. Treatment 2 had a single drip tapeshanked in over conventionally hilled potato in single rows in 36-inch beds (Table 1).Treatment 3 had 2 rows 36 inches apart on a nominal 72-inch bed (72 inches furrow tofurrow) with a drip tape directly above each row of potatoes (Table 1). Treatment 4 had2 rows of plants 36 inches apart on a 72-inch bed with the drip tapes offset 7 inches tothe inside of the bed from each potato row. Treatment 5 had 4 rows of plants on a72-inch bed with 16 inches between the pairs of rows, and the paired rows 14 inchesapart, with the drip tape centered between the pairs of rows. Plants were staggered inthe paired rows.

173

Planting dates and methods, irrigation management, cultural practices, harvest timingand methods, and grading and quality evaluations are all described in the twopreceding reports cited above.

The drip plots were in a completely randomized design with the two varieties as splitplots. The replicated sprinkler-irrigated plots were alongside the drip irrigationexperiment. For simplicity, data were handled as if the sprinkler-irrigated treatmentswere part of a completely randomized trial, which was not the design. Data wereanalyzed with the General Linear Models analysis of variance procedure in NCSS(Number Cruncher Statistical Systems, Kaysville, UT) using the Fisher's Protected LSDmeans separation t-test at the 95 percent confidence level.


The reports cited above describe the soil moisture and water applied. Irrigation plusrainfall varied from 22.15 inches for sprinkler irrigation to 12.59 inches for one of thedrip-irrigated treatments (Table 2). More water was applied to the sprinkler treatmentthan any of the drip treatments and the sprinkler-applied water treatment resulted in thelowest marketable yield per applied water, 13.4 cwt/acre-inch. The drip treatments withthe tape in line with the plant row (treatments 2 and 3) produced less marketable yieldper applied water than the treatments with the drip tape offset from the plant row(treatments 4 and 5). Averaging over production systems, Ranger Russet producedsignificantly more yield of applied water (19.98 cwtfacre-inch) than Umatilla Russet(15.88 cwt/acre-inch). There was no significant interaction between irrigation systemand variety for yield/water applied in terms of cwt/acre-inch.

The yields for all irrigation systems were relatively low in this trial, a reflection of thepoor quality of this site (Table 3). There was a strong interaction between variety andirrigation system. The greatest marketable yield occurred with Ranger Russet grown ona flat bed with a single drip tape for each row of plants (treatment 3). Overall RangerRusset was more productive under drip irrigation than Umatilla Russet. Ranger Russetwas not more productive than Umatilla Russet under sprinkler irrigation (Table 3).

Where the drip tape was shanked directly in line with the potato plants, the productionsystem on flat beds (treatment 3), was 26.7 percent more productive of marketabletubers than the production system with the drip tape in conventional beds (treatment 2).

174

Table 1. Irrigation systems compared for potato production, Maiheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

Treatment

ConfigurationPlant rows p

36-inch bed witbeds hilled

erh the

Plant rows per72-inch bed with

the beds flat

Drip tapeplacement relative

to plant row

1. Sprinkler irrigated 1 row of plants No drip tape,sprinkler irrigated

2. Drip in conventionalpotato hills I row of plants In plant row

3. Drip with flat beds 2 rows of plants In plant row4. Drip with flat beds,

drip tape offset 2 rows of plants Offset 7 inchesfrom plant row

5. Drip with flat beds, 2 double rows of Between doubledrip tape offset plants plant rows

Table 2. Marketable yield, water applied, and wcompared for potato production, Malheur ExperOntario, OR, 2004.

ater use efficiency for irrigation systemsiment Station, Oregon State University,

Treatment

1. Sprinkler irrigated

Marketable yield

cwt/acre300.1

Applied water,irrigation plusprecipitation

acre-inch/acre22.15

Marketable yieldper applied water

cwt/acre-inch13.4

2. Drip in conventionalpotato hills 255.4 14.41 17.7

3. Drip with flat beds 290.1 18.16 17.64. Drip with flat beds,

drip tape offset 309 15 19.8

5. Drip with flat beds,drip tape offset 278 12.59 20.9

LSD (0.05) 2.2

175

Table 3. Ranger Russet and Umatilla Russet performance under five irrigation systems, Maiheur Experiment Station,Oregon State University, Ontario, OR, 2004

Treatment Total TotalU.S.

yieldNo. 1

u•s•No. I

Marketable.yield

U.S. No. 1U.S.No. 2yield

Undersized<4 oz

>12 OZ6 to 12

oz4 to 6

oz

cwt/acre % cwtlacreVariety = Ranger Russet

1. Sprinkler check plots alongside 375.7 230 62.3 291.9 54.4 116.7 58.8 62 64.9 18.92. Hills with drip tape 345.3 249.3 72.2 289.9 30.6 159.6 59 40.7 53.2 2.13. Two row bed, tapes above rows 401.6 306.5 76.2 354.7 84.5 167.1 54.9 48.2 46.2 0.74. Two row bed, tapes offset 7" 385.7 288 74.7 329.3 38.6 187.9 61.4 41.3 55.3 1.15. Four row bed, tapes between pairs of 367.1 252.8 68.7 300.3 33.6 160.8 58.3 47.6 65.5 1.3rowsMean 375.1 265.3 70.8 313.2 48.4 158.4 58.5 47.9 57 4.8

Variety = Umatilla Russet1. Sprinklercheck plots alongside 363.5 233.7 63.6 308.3 70.9 100.5 62.3 74.6 50 5.22. Hills with drip tape 290.1 141.5 48.9 218.8 5.9 88.4 47.2 77.3 64.1 7.23. Two row bed, tapes above rows 384.9 222.5 58.1 290.3 22.9 131.8 67.9 67.7 94.2 0.54. Two row bed, tapes offset 7" 357.6 204 56.8 263.2 20.4 115.6 68 59.2 91.7 2.75. Four row bed, tapes between pairs of 338.5 165.9 48.9 226.7 15 78.5 72.4 60.8 110.5 1.3rowsMean 346.9 193.5 55.3 261.5 27 103 63.6 67.9 82.1 3.4

Average of both varieties1. Sprinklercheck plots alongside 369.6 231.8 62.9 300.1 62.7 108.6 60.6 68.3 57.5 122. Hills with drip tape 317.7 195.4 60.5 254.4 18.3 124 53.1 59 58.6 4.73. Two row bed, tapes above rows 393.3 264.5 67.2 322.5 53.7 149.5 61.4 57.9 70.2 0.64. Two row bed, tapes offset 7' 371.7 246 65.8 296.3 29.5 151.8 64.7 50.3 73.5 1.95. Four row bed, tapes between pairs of 352.8 209.3 58.8 263.5 24.3 119.7 65.3 54.2 88 1.3rowsMean 361 229.4 63.1 287.4 37.7 130.7 61 57.9 69.6 4.1

LSD (0.05) treatment 42.8 44 NS NS (6%) 30.6 NS (6%) NS NS 20.9 NSLSD (0.05) variety 19.9 15.1 2.7 16.8 7.7 12 NS 8 9.8 NSLSD (0.05) treatment x variety NS 33.5 6.1 37.5 17.2 26.9 NS NS 22 NS

DEVELOPMENT OF NEW HERBICIDE OPTIONS FOR WEED CONTROL INPOTATO PRODUCTION



Introduction

Weed control in potatoes is essential for production of high yielding marketable tubers.Herbicide options in potato production are limited. Outlook®, Spartan®, and Chateau®(previously Valor®) demonstrate great promise for use in potato. Spartan and Chateaurepresent a mode of action that is not currently used in potatoes and offer excellenthairy nightshade control. Outlook (dimethenamid-p) has the same mode of action asDual® but controls a wider spectrum of weeds. Trials were conducted to evaluate newherbicides for weed control in potatoes. The results of our research have beenprovided to herbicide companies, the 1R4 program, and state regulators in support ofadditional herbicide registrations in potatoes. Spartan was registered for use in potatoin 2004 and Outlook is registered for use in potato in 2005. Chateau is also registeredfor use in potato and will be available in limited quantities for commercial evaluation for2005. The registration of these herbicides gives producers additional tools forcontrolling weeds and may increase economic returns through improved weed control.


Three trials were conducted at the Malheur Experiment Station to evaluate newherbicides for weed control efficacy and crop tolerance in potatoes: Spartan alone andin 2- and 3-way tank mixtures; comparisons of standard 2-way tank mixtures withChateau or Matrix® added in 3-way tank mixtures; and Outlook in 2- and 3-way tankmixtures. In fall 2003, 50 lb nitrogen (N) and 100 lb phosphorus was appliedprior to bedding in all trial areas. On October 17, 2003, Telone II" (20 gal/acre) andVapam® (20 gal/acre) were applied and the ground was bedded. Potatoes wereplanted April 27, 2004 in an Owyhee silt loam soil with pH 7.6, 2.7 percent organicmatter content, and a cation exchange capacity of 19. 'Russet Burbank' seed pieceswere planted 9 inches in 36-inch-wide rows. Seed pieces were treated with Tops-MZ® plus GauchoR. Experimental plots were 4 rows wide and 30 ft long. Plots weresidedressed with 102 lb N, 4 lb P, 9 lb potassium (K), 8 lb sulfate, 32 lb elemental sulfur(S), 5 lb zinc (Zn), and 1 lb boron (B)/acre on May 3 and rehilled on May 11.Preemergence herbicides were applied with a CO2-pressurized backpack sprayerdelivering 20 gal/acre at 30 psi and incorporated with approximately 0.5 inch of sprinklerirrigation on May 13. Petiole samples were taken and sent for nitrate analysis on July13. On July 16, 25 lb N/acre was applied through the sprinkler. Aerial fungicideapplications included Bravo® and Ridomil GOldR on June 12, Headline® (12 oz/acre) on

177

June 26, Topsin-M® (20 oz/acre) plus liquid sulfur (6 lb/acre) on July 17, and Headline(12 oz/acre) plus liquid sulfur (6 lb/acre) on August 8. In addition, 1.5 lb P and 0.2 lbZn/acre were added to the July 17 fungicide application.

Visual potato injury and weed control were evaluated throughout the growing seasonand tubers were harvested from the center two rows of each plot on September 13-15.Potatoes were graded for yield and size on September 20-27.

Herbicide screening for activity on dodderHerbicides were screened in a petri dish assay to determine effects on doddergermination and elongation. Dodder seeds were scarified using sandpaper and 10seeds were placed in each petri dish. Each dish was treated with 6 ml of watercontaining herbicides at rates equivalent to what would be applied in the field. Doddergermination was counted 4 and 5 days after treatment (DAT), and dodder shoot lengthwas measured 5 DAT.


Spartan alone and in 2- and 3-way tank mixturesControl of all weeds present in this trial was 93 percent or greater by treatments withSpartan alone or combined with other herbicides (Table 1). Spartan caused potatoinjury on June 9, consisting of interveinal chlorosis and necrosis on one set of leaves,and injury tended to be greater with higher rates of Spartan (Table 1). No differences inpotato yield were observed between herbicide treatments, suggesting that the injurywas transient (Table 2).

Comparisons of standard 2-way tank mixtures with Chateau or Matrix added in 3-way tank mixturesThe 2-way tank mixtures provided the same level of control as 3-way tank mixturesincluding either Chateau or Matrix (Table 3). The exception was the combination ofProwl® plus Eptam®, where pigweed control was increased with the addition of Matrix.The 3-way combination of Prowl, Eptam, and Chateau had lower pigweed andbarnyardgrass control than most other treatments. Plots treated with Chateau exhibitedsevere injury on May 26 (Table 3). Injury symptoms included stunting and crinkling ofnewly emerged shoots and leaves. Rainfall events at the time of potato emergencemay have increased the contact of Chateau with the emerging foliage. Sometreatments were still causing significant injury on June 9. In one instance, thecombination of Prowl, Eptam, and Chateau yielded lower than Prowl plus Eptam (Table4). This could have been a result of the early injury when Chateau was in the tankmixture.

Outlook in 2- or 3-way tank mixturesOutlook combined with Prowl or Sencor® in 2-way tank mixtures or with both in a 3-waytank mixture provided 96 percent or greater control of all weeds (Table 5). Potato yieldswere not different among herbicide treatments (Table 6).

178

Herbicide screening for activity on dodderOnly Nortron® suppressed dodder germination compared to the untreated check (Table7). However, all herbicides except Chateau shortened shoot length compared to theuntreated check. Nortron caused the greatest reduction followed by Kerb®, Prowl,Spartan, and Nortron and Kerb are not registered for use in potato. The factthat Prowl and Spartan reduced dodder shoot growth suggests they may be useful inmanaging dodder in potatoes. In this trial, both Prowl and Spartan rates were higherthan those registered for use in potato. Additional research needs to be done withProwl and Spartan rates that are used in potato production.

179

Table 1. Effect of Spartan® alone and in combinations on crop injury and weed controlin potato, Maiheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Treatment* Rate

Weed controlTPotato injury Common Hairy Barnyard5-26 6-9 Pigweed* lambsquarters nightshade Kochia grass

Untreated checkthai/acre

--

0/

- - - - - - -

Spartan 0.094 0 14 100 100 100 100 98

Spartan 0.14 5 20 100 100 100 100 94

Spartan 0.187 3 20 100 100 100 100 98

Spartan+Prowl 0.094+1.0 3 14 100 100 100 100 93

Spartan+ Prowl 0.14+1.0 6 18 100 100 100 100 100

Spartan+DualMagnum 0.094+1.33 0 11 100 100 100 100 100

Spartan+DualMagnum 0.14+ 1.33 6 21 100 100 100 100 100

Spartan+Outlook 0.094+0.84 3 11 100 100 100 100 100

Spartan+Outlook 0.14+0.84 11 15 100 99 100 100 100

Spartan+Eptam 0.094+3.94 3 13 100 100 100 100 97

Spartan+Eptam 0.14+3.94 4 21 100 100 100 100 99

Spartan+ Prowl

+ Eptam0.094+ 1.0

+ 3.943 7 100 100 100 100 99

Spartan+Prowl+ Dual Magnum

0.094+ 1.0+ 1.33

0 11 100 100 100 100 100

Spartan+Prowl+ Outlook

0.094+ 1.0+ 0.84

9 5 100 100 100 100 100

LSD (P = 0.05) -- NS 9 NS NS NS NS NS

13, 2004.*Herbicide treatments were applied preemergence on MaytWeed control evaluations were taken September 2.tPigweed species were a combination of Powell amaranth and redroot pigweed.

180

Table 2. Effect of Spartan® alone and in combinations on potato yield and quality,Maiheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Treatment* Rate

Potatoyieldt

U.S. No. 1 TotalNo. 2

Total Totalmarketable yield4-6 oz 6-12 oz >12 oz Total Percent

Untreated checklb al/acre

--

cwt/acre106 113 15 234

%

65 5

cwt/acre239 359

Spartan 0.094 90 316 62 467 75 70 537 616

Spartan 0.14 102 293 79 474 78 58 532 606

Spartan 0.187 87 316 86 488 77 70 558 623

Spartan+Prowl 0.094+1.0 91 289 46 427 73 71 497 583

Spartan +Prowl 0.14+ 1.0 91 298 69 457 74 87 544 609

Spartan + Dual Magnum 0.094 + 1.33 91 287 51 429 72 88 516 584

Spartan + Dual Magnum 0.14 + 1.33 77 306 65 447 75 71 518 592

Spartan + Outlook 0.094 + 0.84 81 290 65 435 74 76 511 586

Spartan + Outlook 0.14 + 0.84 85 295 64 444 73 82 525 601

Spartan + Eptam 0.094 + 3.94 93 296 54 443 74 80 522 598

Spartan + Eptam 0.14 + 3.94 81 319 85 484 78 68 552 617

Spartani-Prowl+ Eptam

0.094+1.0+ 3.94

102 311 64 476 76 71 547 624

Spartan + Prowl+ Dual Magnum

0.094 + 1.0+ 1.33

97 275 39 411 72 83 493 572

Spartan+Prowl+ Outlook

0.094+1.0+ 0.84

90 290 66 446 75 67 513 590

LSD (P = 0.05) -- NS 53 37 74 6.8 26 72 63

*Herbicide treatments were applied preemergence on May 13, 2004.were harvested September 13 to 15. Total marketable yield = total number ones + total number twos.

181

Table 3. Comparison of standard 2-way tank mixtures with Chateau® or Matrix® addedin 3-way tank mixtures for potato crop injury and weed control, Maiheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

Weed controlTPotato injury Common Hairy Barnyard

Treatment* Rate 5-26 6-9 Pigweedt lambsquarters nightshade Kochia grass

lbai/acre 0/

Untreated check -- - - - - - - -

Dual Magnum + Sencor 1.33 + 0.5 3 3 99 100 96 100 100

Prowl+Sencor 1.0+0.5 0 0 100 100 100 100 100

Dual Magnum + Prowl 1.33 + 1.0 0 0 97 99 99 100 100

Prowl + Eptam 1.0 + 3.94 0 3 93 100 97 100 97

DualMagnum+Sencor 1.33+0.5 35 15 100 100 100 100 100+ Chateau + 0.048

Sencor+Prowl 0.5+1.0 32 8 99 100 100 100 98+ Chateau + 0.048

Dual Magnum+ Prowl 1.33+ 1.0 34 11 99 99 100 100 100+ Chateau + 0.048

Prowl + Eptam 1.0 + 3.94 33 6 93 100 100 100 92+ Chateau + 0.048

Dual Magnum + Sencor 1.33 + 0.5 1 0 100 100 94 100 100+ Matrix + 0.0234

Sencor+ Prowl 0.5+ 1.0 0 0 100 100 98 100 100+ Matrix + 0.0234

Dual Magnum+ Prowl 1.33+ 1.0 3 3 100 100 100 100 100+ Matrix + 0.0234

Prowl + Eptam 1.0 + 3.94 0 0 100 100 100 100 100+ Matrix + 0.0234

LSD (P = 0.05) -- 4 5 5 NS NS NS 4

2004.*Herbicide treatments were applied preemergence on May 13,tWeed control evaluations were taken September 2.tpigweed species were a combination of Powell amaranth and redroot pigweed.

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Table 4. Effect of standard 2-way tank mixtures with Chateau® or Matrix® added in 3-way tank mixtures on potato yield and quality, Maiheur Experiment Station, OregonState University, Ontario, OR, 2004.

Treatment* Rate

Potat o yieldt

U.S. No. 1 Total TotalNo. 2 marketable

Totalyield4-6 oz 6-12 oz >12 oz Total Percent

Untreated checklbai/acre

--cwtlacre

90 154 4 247%65

cwt/acre20 268 380

Dual Magnum + Sencor 1.33 + 0.5 93 290 69 450 75 76 526 602

Prowl + Sencor 1.0 + 0.5 88 303 68 459 76 67 526 606

Dual Magnum + Prowl 1.33 + 1.0 84 285 87 457 77 70 527 596

Prowl + Eptam 1.0 + 3.94 88 319 87 493 79 64 557 625

Dual Magnum + Sencor+ Chateau

1.33 + 0.5+ 0.048

94 290 63 447 74 53 501 602

Sencor+ Prowl+ Chateau

0.5+ 1.0+ 0.048

103 275 68 445 75 64 509 597

Dual Magnum + Prowl+ Chateau

1.33 + 1.0+ 0.048

90 268 66 424 73 60 484 583

Prowl+Eptam+ Chateau

1.0+3.94+ 0.048

99 272 49 419 74 47 467 568

Dual Magnum + Sencor+ Matrix

1.33 + 0.5+ 0.0234

87 294 81 462 74 81 543 624

Sencor + Prowl+ Matrix

0.5 + 1.0+ 0.0234

92 306 76 473 76 64 537 625

Dual Magnum+Prowl+ Matrix

1.33+ 1.0+ 0.0234

78 315 116 508 78 65 574 649

Prowl + Eptam+ Matrix

1.0 + 3.94+ 0.0234

101 284 50 437 72 76 514 603

LSD (P = 0.05) -- NS 36 28 47 5 30 50 44

2004.*Herbicide treatments were applied preemergence on May 13,tpotatoes were harvested September 13 to 15. Total marketable yield = total number ones + total number twos.

183

Table 5. Potato injury and weed control with Outlook®, Prowl H20®, and Sencor®

combinations, Malheur Experiment Station, Oregon State University, Ontario, OR,2004.

Treatment* Rate

Weed control7Potato injury Common Hairy Barnyard5-26 6-9 Pigweedt lambsquarters nightshade Kochia grass

lbai/acre 0/

Untreated check -- - - - - - - -

Prowl H20 + Outlook 1.0 + 0.656 6 0 98 100 98 100 100

ProwlH2O+Outlook 1.0+0.84 6 0 100 100 100 100 100

Outlook + Sencor 0.656 + 0.5 0 0 100 100 97 100 100

Outlook + Sencor 0.84 + 0.5 1 0 100 100 96 100 100

Prowl H2O + Outlook+ Sencor

1.0 + 0.656+ 0.5 1 0 100 100 1100 00

Prowl H2O + Outlook+Sencor

1.0 + 0.84+0.5 1 0 100 100 97 100 100

LSD (P = 0.05) -- 5 NS NS NS NS NS NS

*Herbicide treatments were applied preemergence on May 13, 2004.TWeed control evaluations were taken September 2.

species were a combination of Powell amaranth and redroot pigweed.

®Table 6. Influence of Outlook®, Prowl H20®, and Sencor combinations on potato yieldand quality, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Potato yieldt

U.S. No. 1 TotalNo. 2

Totalmarketable

TotalyieldTreatment* Rate 4-6 oz 6-12 oz >12 oz Total Percent

lbai/acre cwt/acre % cwtlacre

Untreated check -- 98 146 9 252 66 16 268 380

Prowl H2O + Outlook 1.0 + 0.656 91 302 74 467 77 67 534 606

Prowl H2O + Outlook 1.0 + 0.84 98 304 67 470 75 73 543 628

Outlook + Sencor 0.656 + 0.5 74 316 84 474 77 71 545 619

Outlook + Sencor 0.84 + 0.5 98 280 57 45 75 56 490 575

Prowl H2O + Outlook 1.0 + 0.65690 279 56 425 72+ Sencor + 0.5 72 497 589

Prowl H2O + Outlook 1.0 + 0.8490 288 59 437 75+ Sencor + 0.5 64 501 584

LSD (P = 0.05) -- NS 55 30 64 6 26 61 54

*Herbicide treatments were applied preemergence on May 13, 2004.tpotatoes were harvested September 13 to 15. Total marketable yield = total number ones + total number twos.

184

Table 7. Doddscreening trial,2004.

er germination and shoot length in response to herbicides in aMalheur Experiment Station, Oregon State University, Ontario,

petri-dishOR,

Treatment*

DodderGermination

Equivalent rate Rate 4 DAT 5 DATShootlengtht

Untreatedlb al/acre mg al/liter %

-- 85 88----mm----

58

Prowl 1.5 170 73 73 16

Kerb 2.0 227 90 93 12

Dacthal 5.0 567 83 85 32

Chateau 0.096 11 80 83 61

Matrix 0.0234 2.7 68 75 46

Spartan 0.25 28 87 87 24

Nortron 3.0 340 0 10 1.3

LSD(P=0.05) -- -- 15 16 3.8

*Herbicide treatments were applied in 5 ml of water on August 12, 2004.tDodder shoot length was measured only on shoots that had emerged by 4 DAT.

185

SUGAR BEET VARIETY 2004 TESTING RESULTS

Eric Eldredge, Clinton Shock, and Monty SaundersMalheur Experiment Station


Introduction

The sugar beet industry, in cooperation with Oregon State University, tests commercialand experimental sugar beet varieties at multiple locations each year to identifyvarieties with high sugar yield and root quality. A seed advisory committee evaluatesthe data each year to select the best varieties for sugar beet production. This reportprovides the agronomic practices, experimental procedures, and sugar beet root yieldand quality for the Maiheur Experiment Station location of the 2004 trials.

Methods

Sugar beet varieties were entered by ACH Seeds, Betaseed, Hilleshog/Syngenta, HollyHybrids, and Seedex in 2004. Twenty-nine varieties were tested in the CommercialTrial, and 31 varieties (including the 4 commercial check varieties) were tested in theExperimental Trial. Seed for the Commercial Trial was organized by AmalgamatedSugar Company. Seed of Experimental varieties was sent by the seed companies.

The sugar beet trials were grown on an Owyhee silt loam that had grown winter wheatthe year before. The grain stubble was chopped and the field was irrigated and disked,then 60 lb nitrogen (N)/acre, 50 lb phosphate (P205)/acre, 80 lb potash (K2O)/acre, 57lb sulfur (S)/acre, 8 lb zinc (Zn)/acre, 5 lb copper (Cu)/acre, and 3 lb boron (B)/acrewere applied according to fall soil sampling results. The field was then disked, ripped,plowed, and groundhogged. On November 7, the soil was fumigated with Tetone C17®at 15 gal/acre, and fall bedded on 22-inch rows.

On March 30, the beds were dragged off using a spike-tooth bed harrow with 3.75-inchangle iron furrow slickers. Preplant herbicide Nortron® at 6 pint/acre was applied andincorporated using the bed harrow. Both the Experimental Trial and the CommercialTrial were planted on April 1. Seeds were planted in four-row plots with John Deeremodel 71 flexi-planter units with double disc furrow openers and cone seeders fed froma spinner divider that uniformly distributed the seed. Plots of each variety were 4 rowswide (22-inch row spacing) by 23 ft long, with a 4-ft alley separating each tier of plots.The seeding rate was 12 viable seed/ft of row. Each entry was replicated eight times ina randomized complete block design.

A soil test taken on April 4, 2004, showed pH 7.8, 2.9 percent organic matter, 32 lbnitrate (N03)/acre available in the top 2ft of soil, 20 ppm extractable phosphorus (P),

186

256 ppm exchangeable potassium (K), 10 ppm sulfate (SO4), 433 ppm magnesium(Mg), 82 ppm sodium (Na), 4.1 ppm Zn, 5 ppm iron (Fe), 1 ppm manganese (Mn), 0.6ppm Cu, and 0.8 ppm B.

On April 5 Counter 2OCR® was applied in a band over the row at 7.4 lb/acre (5 oz/1 ,000ft of row). The first irrigation was applied on April 9, for 24 hours. A 44.5-hour irrigationon April 12 that was applied to wet the seed rows for more uniform germination wasfollowed by 0.9 inch of rain April 19-21. On April 27, Poast® herbicide was applied at2pint/acre to control grasses and volunteer wheat. On May 4, a tank mix of BetamixR at32 oz/acre, UpbeetR at 0.5 oz/acre, and Stinger® at 3 oz/acre was applied for weedcontrol. Seedlings were thinned by hand to 1 plant every 6.4 inches on May 10 and 11.On May lithe plots of two entries in the Experimental Trial that failed to emerge werereplanted with the border variety, PM21.

The field was sidedressed with Temik 15G® at 10 lb/acre on May 13 to control sugarbeet root maggot, and the field was irrigated for 24 hours to move the insecticide withthe wetting front into the sugar beet seedlings' root zone. On May 25, urea wassidedressed to supply 182 lb N/acre. On May27 the field was cultivated and

with 9-inch sweeps ahead of 6-inch angle iron furrow slickers. On June 1,TreflanR herbicide was applied at 1.5 pint/acre and incorporated with the samecultivator.

The field was furrow irrigated with surge irrigation from gated pipe. Irrigation wasmonitored with Watermark soil moisture sensors Model 200SS (Irrometer Co. Inc.,Riverside, CA) connected to an AM400 Hansen datalogger (M.K. Hansen Co.,Wenatchee, WA) to maintain the soil water potential wetter than -70 centibar (kPa) at10-inch depth in the beet row.

A petiole test was taken on June 14, and Thio-SuI® was applied in the irrigation wateron June 21 to supply 25 lb N plus 33 lb SO4/acre. Headline® fungicide was applied at12 oz/acre by aerial applicator on June 25 for control of powdery mildew. On June 28, asecond petiole test was taken and the field was recorrugated the final time. On July 6,20 lb N/acre, 10 lb P2O5/acre, 10 lb SO4/acre, 0.25 lb Zn/acre, and 0.2 lb B/acre wereapplied in the irrigation water. A third petiole test was taken on July 12, and on July 15,5 lb Mg/acre, 7 lb SO4/acre, and 0.5 lb B/acre were applied in the irrigation water. OnJuly 17, Topsin-M® fungicide at 20 oz/acre was applied by airplane in a spray mixturethat included S at 6 lb/acre, P205 at 1.5 lb/acre, and Zn at 0.2 lb/acre. An aerialapplication of Headline fungicide at 12 oz/acre plus sulfur at 6 lb/acre was applied onAugust 8.

The final irrigation was applied on September 2. Visual estimates of curly top virus andpowdery mildew foliar symptoms were recorded for each plot in the Experimental Trialon September 10, and for each plot in the Commercial Trial on September 16. Boltedbeets were counted when the disease ratings were made.

187

Sugar beets were harvested from the Experimental Trial on October 13 and 14, andfrom the Commercial Trial on October 14 and 15. The foliage was flailed and thecrowns were removed with rotating knives. All sugar beets in the center two rows ofeach plot were dug with a two-row wheel-lifter harvester and weighed, and two eight-beet samples were taken from each plot. Samples were delivered each day to theSnake River Sugar factory in Nyssa for laboratory analysis of percent sucrose, nitrateconcentration, and conductivity.

The root weight data were examined for outliers as is customary for calculations ofsugar beet variety data by Amalgamated in these trials. Observations more than twostandard deviations from the mean for each variety were deleted. Sugar sample datawere checked for errors in sugar percentages and conductivity. Any erroneous samplereadings were deleted from the data set. The companion samples of all missing ordeleted sugar data were good, so no plots were lost due to sugar sample errors.

The weight of sugar beets from each plot was multiplied by 0.90 to estimate tare. Sugarconcentrations were "factored" by multiplying measured sucrose by 0.98 to estimate thesugar that would have been lost to respiration if the beets had been stored in a pile.The data for each plot with two samples were averaged for analysis. The percentextraction was calculated using the formula:

Ext = 250 + [(1,255.2 * Cond) -(15,000 * Sug) -6,185]! Sug * (98.66- 7.845 * Cond)

where Ext is percent extraction, Cond is the electrical conductivity in mm ho, and Sug isthe sugar concentration in percent.

Variety differences in yield, sucrose content, conductivity, percent extraction, andestimated recoverable sugar were calculated using least-squares means analysis.Sugar beet performance in both trials was compared to the check varieties ACH Seeds'Crystal 217R', Betaseed 'Beta 4490 R', Hilleshog/Syngenta 'HM2986 Rz', and Seedex'Raptor Rz'. Reports of previous years' Oregon State University variety trials areavailable online at www.cropinfo.net.

Results

Early stand establishment was slow and erratic. The sixth irrigation, on June 29 (thefirst irrigation in the wheel furrows), was effective in wetting the soil and the soilmoisture sensors responded to the irrigation (Fig. 1). Surge irrigation approximatelyonce a week maintained soil water potential wetter than -60 kPa through most of thegrowing season.

Powdery mildew infection developed on sugar beet foliage in these trials and inneighboring growers' fields. Curly top virus foliar symptoms were more severe in thebeets this year than is usually seen (Table 1). In the Experimental Trial, Beta'3YK0019', Beta '4YK0023', Crystal '318R', and Beta '4YK0024' were among thevarieties showing the most severe curly top virus foliar symptoms. SX Raptor RZ, SX

188

'1522', Crystal 217R, and 'O4HX431RZ' were among the varieties showing the mostsevere powdery mildew symptoms in the Experimental Trial. In the Commercial Trial,Beta '4035R', Crystal '9906R', Beta '4490R', and Beta '4614R' were among thevarieties showing the most severe curly top virus foliar symptoms. Beta '4614R', Crystal217R, Crystal '333R', and 'Beta '4773R' were among the varieties showing the mostsevere powdery mildew symptoms in the Commercial Trial.

Variety results were grouped by seed company for the Commercial Trial (Table 2) andthe Experimental Trial (Table 3). Within each seed company's varieties, the varietiesare ranked in descending order of estimated recoverable sugar in pounds per acre. Theroot weights were tared 10 percent in 2004; in previous years, a root tare of 5 percenthad been applied. The truck loads of border row beets delivered to the Nyssa factory in2004 from the same field, dug with the same harvester, ranged from 5 to 7.9 percenttare, and averaged 6.5 percent tare.

Root yield in the Commercial Trial averaged 42.98 tared ton/acre, average sugarcontent was 17.95 percent, and average estimated recoverable sugar was 13,345lb/acre. The varieties yielding among the highest estimated recoverable sugar in theCommercial Trial were 'Beta 8600', with 14,867 lb/acre, Holly Hybrids 'Acclaim R' with14,217 lb/A, and Seedex 'Cascade' with 14,192 lb/acre.

Data for the Experimental Trial are reported in Table 3. Root yield in the ExperimentalTrial averaged 43.37 tared ton/acre, average sugar content was 17.64 percent, andaverage estimated recoverable sugar was 13,144 lb/acre. The varieties yielding amongthe highest estimated recoverable sugar in the Experimental Trial were 'HMPM9O' with14,228 lb/acre, 'HM2993Rz' with 13,933 lb/acre, '04HX422 R' with 13,920 lb/acre, 'Beta4YK0024' with 13,760 lb/acre, '04HX438 R' with 13,733 lb/acre, 'HM 2995Rz' with13,680 lb/acre, 'Beta 2YK0016' with 13,607 lb/acre, and 'HM 2992Rz' with 13,572lb/acre.

189

-20

0C,)

Figure 1. Sugar beet trials average soil water potential of six Watermark soil moisturesensors read by an AM400 Hanson datalogger, Oregon State University, MalheurExperiment Station, Ontario, OR, 2004.

190

Date, 2004

-0

-10

(C

0(0

(N(0 N- N-

aD IC)

N- CO (0

IC)

(0

(\)

CO

C)

(C(0a)

-60

-70

-80

Table 1. Visual evaluations of foliar disease symptoms and bolting in sugar beetvarieties, Oregon State University, Malheur Experiment Station, Ontario, OR, 2004.

tAverage curly top virus symptom severity rating from 0 (none) to 10.powdery mildew fungus symptom severity rating from 0 (none) to 10.

§Average number of bolted beets per 4-row plot, 23 feet long.

191

Experimental Trial

10 September CTt

Commercial Trial

16 September CTt BolP

HM2986RZ 1.8 1.6 0.0 HM1642 2.3 2.3 0.0

HM2991 RZ 4.0 1.8 0.0 HM298ORZ 4.1 1.8 0.0

HM2992 RZ 3.9 1.5 0.0 HM2984RZ 1.9 2.4 0.0

HM2993 RZ 0.9 1.4 0.0 HM2986RZ 1.9 2.2 0.0

HM2994 RZ 0.9 1.9 0.0 HM2988RZ 3.8 1.6 0.0HM2995 RZ 2.9 1.9 0.0 HM2989RZ 2.4 2.3 0.0

HM PM9O 0.8 1.5 0.0 HMAlliance 1.4 2.4 0.4

PM21 replant 1.9 1.2 0.0 HM Oasis 0.9 1.5 0.0

PM21 replant 1.5 1.1 0.0 HM Owyhee 1.2 2.4 0.003HX353RZ 1.2 1.8 0.0 HM PM21 0.8 1.4 0.004HX422RZ 1.9 1.8 0.4 Acclaim RZ 1.8 1.4 0.0O4HX431RZ 1.3 2.3 7.4 Eagle RZ 2.5 2.0 0.004HX434RZ 1.8 1.8 0.4 HH142 RZ 4.3 1.1 0.004HX436RZ 2.3 2.0 0.0 Meridian RZ 1.9 1.9 0.004HX437RZ 1.6 1.3 1.3 PhoenixRZ 3.3 2.1 0.004HX438RZ 2.2 1.9 0.0 Cascade 0.9 0.9 0.0SX Raptor RZ 3.6 3.0 0.0 Puma 1.2 2.5 0.0SX1 521 2.7 2.1 0.0 Raptor RZ 4.8 2.5 0.0SX1 522 2.6 2.7 0.0 ACH Mustang 2.0 2.5 0.0Crystal 217R 1.8 2.3 0.8 Crystal 217R 2.3 3.3 0.0Crystal 316R 1.1 2.0 0.0 Crystal333R 3.5 3.0 0.0Crystal 318R 4.5 1.4 0.0 Crystal99O6R 5.8 2.9 0.0Crystal4llR 1.4 1.8 0.0 Beta4O35R 6.4 2.8 0.0Crystal4l2R 1.3 1.4 0.0 Beta4l99R 5.0 2.5 0.0Beta449OR 3.6 1.6 0.0 Beta 4490R 5.8 2.3 0.0Beta2YKOOl6 1.4 1.6 0.0 Beta46l4R 5.1 3.8 0.0Beta3YKOOl9 5.8 1.9 0.0 Beta4773R 1.8 3.0 0.0Beta 3YK0020 1.5 1 .4 0.0 Beta 8220B 2.9 2.4 0.0Beta 4YK0023Beta4YKOO24

5.34.5

1.8

1.1

0.0

0.0Beta 8600 2.3 1.1 0.0

Mean 2.9 2.2 0.0Beta 4YK0025 3.6 1.5 0.0 LSD (0.05) 1.3 0.8 0.1

MeanLSD (0.05)

2.4 1.7 0.31.3 0.9 0.8

Table 2. Commercial sugar beet variety root yield, sugar content, root quality,recoverable sugar, and nitrate content from varieties entered in the trial at MalheurExperiment Station, Oregon State University, Ontario, OR, 2004.

Root Sugar Gross Conduc- Extrac- Estimated Nitrateyield

Variety ton/acrecontent sugar tivity tion recoverable content

% lb/acre mmho %

sugarlb/ton lb/acre ppm

ACH SeedsACH Mustang 44.83 17.79 15,931 0.701 85.79 305.1 13,666 119Crystal 9906R 40.09 17.99 14,415 0.571 8751 314.8 12,614 102Crystal 217R 39.05 18.44 14,417 0.661 86.41 318.8 12,457 136Crystal 333R 36.93 18.34 13,546 0.691 86.00 315.4 11,647 95BetaseedBeta 8600 47.71 17.99 17,158 0.638 86.65 311.8 14,867 106Beta4l99R 42.97 18.21 15,650 0.678 86.16 313.8 13,482 110Beta 8220B 43.14 18.19 15,687 0.721 85.59 311.6 13,430 112Beta 4035R 44.19 17.50 15,459 0.633 86.62 303.2 13,392 126Beta 4490R 41.52 18.60 15,436 0.662 86.43 321.5 13,340 85Beta 4773R 39.51 18.53 14,654 0.649 86.59 321.0 12,691 112Beta 4614R 41.92 17.15 14,374 0.611 86.83 297.8 12,481 110Hilleshog/SyngentaHM1642 42.24 18.81 15,887 0.578 87.55 329.3 13,908 111HM Owyhee 43.73 18.19 15,910 0.613 87.00 316.6 13,842 113HM 2989Rz 43.32 18.43 15,962 0.661 86.42 318.6 13,794 149HM PM21 42.88 18.29 15,680 0.579 87.45 319.9 13,711 110HM 2986Rz 42.13 18.46 15,550 0.597 87.25 322.2 13,569 104HMAlliance 42.07 18.26 15,365 0.554 87.76 320.5 13,486 108HM Oasis 42.68 17.93 15,316 0.593 87.21 312.8 13,359 123HM 2980Rz 42.59 18.00 15,310 0.678 86.12 310.1 13,183 131HM2984Rz 42.73 17.77 15,192 0.630 86.70 308.2 13,173 141HM2988Rz 40.56 18.24 14,798 0.562 87.66 319.7 12,971 144Holly HybridsAcclaim R 48.63 17.13 16,662 0.727 85.32 292.4 14,217 146PhoenixR 47.30 17.11 16,174 0.678 85.96 294.1 13,900 138Meridian R 46.49 17.28 16,063 0.676 86.02 297.3 13,817 162EagleR 45.93 17.18 15,763 0.704 85.62 294.1 13,497 123HH 142 R 42.53 17.28 14,681 0.708 85.59 295.8 12,567 151SeedexSX Cascade 45.69 17.71 16,178 0.550 87.72 310.8 14,192 101SX Puma 41.40 18.04 14,932 0.588 87.29 315.0 13,032 123SX Raptor Rz 42.04 17.77 14,927 0.665 86.25 306.5 12,873 150Mean 42.98 17.95 15,412 0.640 86.60 311.0 13,345 122LSD (0.05) 2.51 0.50 914 0.040 0.55 9.6 792 43LSD (0.10) 2.11 0.42 766 0.034 0.46 8.1 664 36CV (%) 5.9 2.8 6.0 6.3 0.6 3.1 6.0 35.6

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Table 3. Experimental sugar beet variety root yield, sugar content, root quality,recoverable sugar, and nitrate content from varieties entered in the trial at MalheurExperiment Station, Oregon State University, Ontario, OR, 2004.

Variety

Rootyield

Sugarcontent

Grosssugar

Conduc-tivity

Extrac-tion

Estimatedrecoverable sugar

Nitratecontent

ton/acre % lb/acre mmho % lb/ton lb/acre ppm

ACH SeedsCrystal 316R 45.29 17.39 15,720 0.710 85.59 297.7 13,450 168

Crystal 318R 43.00 17.61 15,144 0.513 88.17 310.5 13,354 144

Crystal4llR 44.28 17.44 15,443 0.768 84.85 296.0 13,101 166

Crystal 412R 42.71 17.50 14,951 0.759 84.96 297.4 12,705 170

Crystal 217R 41.28 17.48 14,440 0.721 85.46 298.8 12,344 233BetaseedBeta 4YK0024 45.03 17.79 16,021 0.693 85.89 305.6 13,760 126

Beta 2YK0016 45.61 17.55 15,993 0.751 85.09 298.8 13,607 223Beta 4YK0023 42.19 18.37 15,467 0.656 86.46 317.7 13,367 137Beta 3YK0019 43.72 17.78 15,532 0.706 85.71 304.8 13,312 177Beta 4490R 42.59 18.06 15,377 0.714 85.65 309.4 13,170 163Beta 4YK0025 42.19 17.94 15,129 0.681 86.08 308.9 13,021 158Beta 3YK0020 43.67 17.13 14,958 0.711 85.53 293.1 12,793 170HilleshoglSyngentaHM PM9O 44.48 18.38 16,354 0.616 87.00 319.9 14,228 190HM 2993Rz 47.33 17.25 16,328 0.728 85.33 294.5 13,933 219HM 2995Rz 44.86 17.68 15,846 0.657 86.34 305.2 13,680 176HM 2992Rz 44.71 17.64 15,773 0.680 86.03 303.5 13,572 176HM2986Rz 42.87 17.90 15,342 0.646 86.52 309.8 13,274 149HM2991Rz 40.99 18.22 14,931 0.547 87.85 320.2 13,116 138HM2994Rz 39.69 17.88 14,199 0.715 85.61 306.2 12,157 189Holly Hybrids04HX422 R 49.51 16.46 16,286 0.706 85.46 281.4 13,920 20904HX438 R 48.02 16.68 16,017 0.688 85.74 286.1 13,733 191

04HX437 R 45.70 17.11 15,627 0.759 84.90 290.5 13,266 25004HX434 R 43.06 17.70 15,245 0.613 86.92 307.7 13,251 20104HX436 R 44.39 17.26 15,316 0.733 85.26 294.4 13,061 21703HX353 R 40.12 17.93 14,384 0.602 87.10 312.3 12,528 141

04HX431 R 38.44 17.43 13,385 0.649 86.39 301.1 11,561 205SeedexSX Raptor Rz 43.03 17.43 14,992 0.697 85.77 299.1 12,853 206SX1522 39.54 18.37 14,526 0.634 86.76 318.8 12,601 172SX1521 39.71 18.15 14,408 0.663 86.34 313.5 12,441 187

Mean 43.37 17.64 15,280 0.680 86.03 303.6 13,144 181

LSD (0.05) 2.50 0.45 886 0.048 0.67 9.3 763 51

LSD (0.10) 2.10 0.38 742 0.040 0.56 7.8 639 43CV (%) 5.8 2.6 5.8 7.0 0.8 3.1 5.8 28.4

193

KOCHIA CONTROL WITH PREEMERGENCE NORTRON® IN STANDARD ANDMICRO-RATE HERBICIDE PROGRAMS IN SUGAR BEET



Introduction

The distribution of kochia resistant to UpBeet® (triflusulfuron) herbicide and otheracetolactate synthase (ALS) inhibitors (i.e., sulfonylureas, imidazolinones, andtriazolopyrimidines) has increased in recent years and poses a serious problem insugar beet production, as none of the currently registered postemergence herbicideseffectively control ALS-resistant kochia. In this trial, Nortron® (ethofumesate) wasevaluated for preemergence control of kochia in sugar beet. Nortron is a soil-activeherbicide used preemergence or early postemergence to control annual grasses andbroadleaf weeds.

Methods

This trial was established at the Malheur Experiment Station under furrow irrigation onApril 8, 2004. Sugar beets (Hilleshog 'PM-21') were planted in 22-inch rows at a 2-inchseed spacing. On April 9, the trial was corrugated and Counter 20 CR® was applied ina 7-inch band over the row at 6 oz/1 000 ft of row. Sugar beets were thinned to 8-inchspacing on May 10 to 13. Plots were sidedressed on June 2 with 175 lb nitrogen(urea), 30 lb potash (K2O), 35 lb sulfates (SO4), 38 lb elemental sulfur (S), 3 lbmanganese (Mn), 2 lb zinc (Zn), and 1 lb/acre boron (B). All plots were treated withRoundup® lb ai/acre) on April 13 prior to sugar beet emergence. On May 26,Temik 15GR (14 lb prod/acre) was applied for sugar beet root maggot control. Forpowdery mildew control, Headline® (12 fI oz/acre) was applied on June 25, Topsin M®(20 oz prod/acre) plus S at 6 lb/acre, phosphate (P205) at 1.5 lb/acre, and Zn at 0.2lb/acre were applied August 4, and Headline (12 fI oz/acre) plus S at 6 lb/acre wereapplied August 8. All fungicide treatments were applied by air. Herbicide treatmentswere broadcast-applied with a CO2-pressurized backpack sprayer calibrated to deliver20 gal/acre at 30 psi. Plots were 4 rows wide and 27 ft long and treatments werearranged in a randomized complete block design with 4 replicates.

The treatments in this trial consisted of both standard and micro-rate postemergenceweed control programs applied with or without a preemergence application of Nortron ateither 16, 24, or 32 oz ai/acre with and without postemergence UpBeet. For the micro-rate treatment without UpBeet, Nortron was also applied preemergence at 48 ozai/acre. UpBeet was omitted from selected treatments to simulate ALS resistance andto better evaluate preemergence Nortron efficacy on kochia. Nortron was applied

194

preemergence on April 13. The standard rate program included three applications, withthe first applied to full cotyledon sugar beets on April 26, the second to two- to four-leafsugar beets on May 3, and the third application to six- to eight-leaf sugar beets on May14. Progress (ethofumesate + phenmedipham + desmedipham) was applied at 4.0,5.4, and 6.7 oz ai/acre in the first, second, and third applications, respectively. UpBeetwas applied at 0.25 oz ai/acre in all three applications (excluding treatments whereUpBeet was omitted). Stinger® (clopyralid) was applied in the second and thirdapplications at 1.5 oz ai/acre. The micro-rate program consisted of four applicationswith the first applied to cotyledon sugar beets on April 23, the second to cotyledon to 2-leaf sugar beets on April 30, the third application was inadvertently delayed and wasapplied to 8-to 10-leaf sugar beets on May 15, and the fourth to 8-to 12-leaf sugarbeets on May 20. In the micro-rate program, Progress® was applied at 1.3 oz ai/acre inthe first two applications and at 2.0 oz ai/acre in the last two applications. All fourmicro-rate applications included UpBeet at 0.08 oz ai/acre (excluding treatments whereUpBeet was omitted), Stinger at 0.5 oz ai/acre, and a methylated seed oil (MSO) at 1.5percent v/v.

Sugar beet injury was evaluated May 10 and June 9 and weed control was evaluatedSeptember 3. Sugar beet yields were determined by harvesting the center two rows ofeach plot on October 8 and 9. Root yields were adjusted to account for a 5 percenttare. One sample of 16 beets was taken from each plot for quality analysis. Thesamples were coded and sent to Syngenta Seeds Research Station in Nyssa, Oregon,to determine beet pulp sucrose content and purity. Sucrose content and recoverablesucrose were estimated using empirical equations. Data were analyzed using analysisof variance procedures and means were separated using protected LSD at the 95percent confidence interval (P = 0.05). The untreated control was not included in theanalysis of variance for weed control or crop response.


Postemergence herbicides were very effective this year. Kochia control was greaterthan 98 percent with either the standard rate or micro-rate treatments containingUpBeet regardless of whether preemergence Nortron was applied (Table 1). RemovingUpBeet from the standard rate and the micro-rate resulted in a respective 18 and 58percent decrease in kochia control on July 17. For the standard rate treatments withoutUpBeet, the addition of Nortron at any rate provided kochia control similar to thestandard rate with UpBeet. For micro-rate treatments without UpBeet, the addition ofpreemergence Nortron, regardless of the rate, did not control kochia as well as themicro-rate with UpBeet. Increasing Nortron rates increased kochia control. Pigweedcontrol also was reduced when UpBeet was omitted from the micro-rate. The additionof Nortron at 16 or 24 oz ai/acre improved kochia control, but the 32- or 48- oz ai/acrerates were required to control kochia equal to the micro-rate with UpBeet. There wereno differences among treatments for common lambsquarters, hairy nightshade, orbarnyardgrass control. Common lambsquarters and hairy nightshade control was 98percent or higher while barnyardgrass control ranged from 87 to 99 percent.

195

Injury on May 10 was significantly higher for standard rate treatments with UpBeetcompared to standard rate treatments without UpBeet or compared to any of the micro-rate treatments (Table 2). Within the micro-rate treatments, the 48- oz al/acre rate ofNortron caused greater injury (23 vs 5-14 percent) than any of the other micro-ratetreatments with or without Nortron preemergence. On June 9, injury was similar amongall treatments. Sugar beet yields were not significantly different among any of thestandard rate treatments. Sugar beet yields were lowest with the micro-rate appliedwithout UpBeet. The addition of preemergence Nortron at 32 oz al/acre to the micro-rate without UpBeet was the only treatment that produced yields similar to the micro-rate with UpBeet. The lower Nortron rates had lower yields and the 48- oz al/acreNortron treatment also yielded less than the micro-rate with UpBeet. The lower yieldwith the high rate of Nortron may have been related to the increased sugar beet injury.

In areas where kochia has become resistant to UpBeet, a preemergence application ofNortron followed by postemergence herbicides at standard rates should provideeffective control. Removing UpBeet from the spray mixture may not be advisable sinceUpBeet would still be effective in controlling non-UpBeet-resistant kochia and also helpscontrol other weeds. The micro-rate should not be used in areas with UpBeet resistantkochia because even with high rates of preemergence Nortron, acceptable kochiacontrol cannot be achieved.

196

Table 1. Kochia control with preemergence Nortron® in standard and micro-rateherbicide programs, Maiheur Experiment Station, Oregon State University, Ontario, OR,2004.

Treatment* Rate Timingt

Weed control

K hioc a Pigweed Lambs-spp. quarters

Hairynightshade

Barnyard-grass

7-27 9-3 7-27 7-27 7-27 7-27

ozai/acre&%v/v 0/

Untreated control -- -- -- -- -- -- -- --

Standard Rate ProgramProgress + UpBeet 4.0 + 0.25 3 100 100 100 100 99 95Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5 5

Progress + UpBeet + Stinger 6.7 + 0.25 + 1.5 6

Micro-Rate ProgramProgress + UpBeet + Stinger + 1.3 + 0.083 + 0.5 + 24 98 98 97 100 100 97MSO 1.5% v/vProgress + UpBeet + Stinger + 2.0 + 0.083 + 0.5 ÷ 7,8MSO 1.5% v/v

Nortronfb 16.0 1 100 100 99 100 100 97Standard with Upbeet --- 3,5,6

Nortronfb 24.0 1 100 100 100 100 100 98Standard with UpBeet --- 3,5,6

Nortronfb 32.0 1 100 100 100 100 100 99Standard with UpBeet --- 3,5,6

Nortronfb 16.0 1 100 100 100 100 100 93Standard w/out UpBeet --- 3,5,6



Nortronfb 16.0 1 100 100 100 99 100 91Micro with UpBeet --- 2,4,7,8

Nortronfb 24.0 1 99 99 100 100 100 97Micro with UpBeet --- 2,4,7,8

Nortronth 32.0 1 100 100 100 100 100 95Micro with UpBeet

Nortronfb 16.0 1 62 58 91 100 100 93Micro w/out UpBeet --- 2,4,7,8



Standard w/out UpBeet --- 3,5,6 82 88 95 100 100 95

Micro w/out UpBeet --- 2,4,7,8 40 48 80 100 100 87

Nortron fb 48.0 1 84 86 98 98 100 97Micro w/out UpBeet --- 2,4,7,8

LSD ( 0.05) 8 8 6 NS NS NS

*fb = Followed by.tApplication timings were (1) April 13 preemergence, (2) April 23 to cotyledon beets, (3) April 26 to full cotyledon beets, (4) April 30to 2-leaf beets, (5) May 3 to 2- to 4-leaf beets, (6) May 14 to 6- to 8-leaf beets, (7) May 15 to 8- to 10-leaf beets, and (8) May 20 to8- to 12-leaf beets.tpigweed species included Powell amaranth and redroot pigweed.

197

Table 2. Sugar beet injury and yield with preemergence Nortron® in standard andmicro-rate herbicide programs, Maiheur Experiment Station, Oregon State University,Ontario, OR, 2004

Treatment* Rate Timingt

Sugar beet

Injury

5-10 6-9 Root yield Sucrose Extraction ER&0/ lbs/acreoz al/acre and % v/v 0/ ton/acre

Untreated control -- -- -- -- 6.1 16.6 93.5 1,958Standard Rate ProgramProgress + UpBeet 4.0 + 0.25 3 33 21 41.1 16.7 93.6 12,802Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5 5Progress + Upbeet + Stinger 6.7 + 0.25 + 1.5 6

Micro-Rate ProgramProgress + UpBeet + Stinger + 1.3 + 0.083 + 0.5 + 2,4 9 9 44.3 16.5 93.0 13,614MSO 1.5%v/vProgress + UpBeet + Stinger + 2.0 + 0.083 + 0.5 + 7,8MSO 1.5% v/v

Nortron fb 16.0 1 30 18 42.7 17.1 93.4 13,616Standard with UpBeet --- 3,5,6



Nortron fb 16.0 1 13 11 40.6 16.9 93.1 12,770Standard w/out UpBeet --- 3,5,6



Nortron fb 16.0 1 11 18 42.2 16.5 93.7 13,025Micro with UpBeet --- 2,4,7,8

Nortron fb 24.0 1 10 11 42.2 16.3 93.1 12,792Micro with UpBeet --- 2,4,7,8

Nortron fb 32.0 1 13 14 40.5 17.1 93.5 12,918Micro with UpBeet

Nortron fb 16.0 1 11 18 29.4 17.4 93.3 9,509Micro w/out UpBeet --- 2,4,7,8



Standard w/out UpBeet --- 3,5,6 19 13 38.8 17.0 93.4 12,345

Micro w/out UpBeet --- 2,4,7,8 6 6 29.3 17.7 93.9 9,786


LSD (0.05) -- 8 13 6.1 0.8 NS 1,937

*fb = Followed bytApplication timings were (1) April 13 preemergence, (2) April 23 to cotyledon beets, (3) April 26 to full cotyledon beets, (4) April 30to 2-leaf beets, (5) May 3 to 2 to 4-leaf beets, (6) May 14 to 6 to 8-leaf beets, (7) May 15 to 8 to 10-leaf beets, and (8) May 20 to 8to 12-leaf beets.tSugar beets were harvested October 8 and 9.

= estimated recoverable sucrose.

198

TIMING OF DUAL MAGNUM® AND OUTLOOK® APPLICATIONS FOR WEEDCONTROL IN SUGAR BEET



Introduction

Outlook® (dimethenamid-P) and Dual Magnum® (s-metolachlor) are soil-activeherbicides that are labeled for postemergence application in sugar beet. They can beapplied to two-leaf or larger beets. Outlook or Dual Magnum was applied at differenttimings as part of a standard rate herbicide program. The objectives of this trial were to1) determine if weed control can be improved with Outlook or Dual Magnum in thestandard rate program, and 2) determine if the application timing of these herbicidesinfluences weed control or crop response.

Methods

This trial was established at the Malheur Experiment Station under furrow irrigation onApril 8, 2004. Sugar beets (Hilleshog 'PM-21') were planted in 22-inch rows at a 2-inchseed spacing. On April 9, the trial was corrugated and Counter 20 CR® was applied ina 7-inch band over the row at 6 oz/l ,000 ft of row. Sugar beets were thinned to 8-inchspacing on May 10 to 13. Plots were sidedressed on June 2 with 175 lb nitrogen (N)(urea), 30 lb potash (1<20), 35 lb sulfates (SO4), 38 lb elemental sulfur (5), 3 lbmanganese (Mn), 2 lb zinc (Zn), and 1 lb/acre boron (B). All plots were treated withRoundup® lb ai/acre) on April 13 prior to sugar beet emergence. On May 26,Temik 15GR (14 lb prod/acre) was applied for sugar beet root maggot control. Forpowdery mildew control, Headline® (12 ft oz/acre) was applied on June 25, Topsin M®(20 oz prod/acre) plus S at 6 lb/acre, phosphate (P205) at 1.5 lb/acre, and Zn at 0.2lb/acre were applied on August 4, and Headline (12 fI oz/acre) plus S at 6 lb/acre wereapplied on August 8. All fungicide treatments were applied by air. Herbicide treatmentswere broadcast applied with a CO2-pressurized backpack sprayer calibrated to deliver20 gal/acre at 30 psi. Plots were 4 rows wide and 27 ft long and treatments werearranged in a randomized complete block design with 4 replicates.

Outlook, Dual Magnum, and Treflan® were applied at various timings as part of astandard rate herbicide program to evaluate the effect of application timing on weedcontrol and crop response. The standard rate program consisted of Progress® appliedat 4.0, 5.4, and 6.7 oz ai/acre in the first, second, and third applications,UpBeet® was applied at 0.25 oz ai/acre in all three applications and StingerR at 1.5 ozal/acre in the last two applications. Dual Magnum was applied preemergence only, orin the second or third postemergence application, or preemergence and in the second

199

application, or in the second and third applications. Outlook was applied in the secondor third applications. Both Dual Magnum and Outlook were applied in combination withTreflan in the second postemergence application. The preemergence treatments wereapplied April 13. The first, second, and third postemergence applications were madeon April 26, May 3, and May 14, to cotyledon, 2-to 4-leaf, and 6-to 10-leaf beets,respectively.

Sugar beet injury was evaluated on May 10 and June 9 and weed control wasevaluated on September 3. Sugar beet yields were determined by harvesting thecenter two rows of each plot on October 8 and 9. Root yields were adjusted to accountfor a 5 percent tare. One sample of 16 beets was taken from each plot for qualityanalysis. The samples were coded and sent to Syngenta Seeds Research Station inNyssa, Oregon, to determine beet pulp sucrose content and purity. Sucrose contentand recoverable sucrose were estimated using empirical equations. Data wereanalyzed using analysis of variance procedures and means were separated usingprotected LSD at the 95 percent confidence interval (P = 0.05). The untreated controlwas not included in the analysis of variance for weed control or crop response.


The addition of Outlook or Dual Magnum or combinations of Outlook or Dual Magnumwith Treflan improved barnyardgrass control compared to the standard postemergencetreatment alone (Table 1). For all other weeds, control was similar among treatments.There also were no differences in sugar beet injury (Table 2) or sugar beet stand (datanot shown) among treatments. All herbicide treatments had greater yields compared tothe untreated control, but yields did not differ among herbicide treatments.

This research suggests that both Dual Magnum and Outlook can be applied incombination with standard rate herbicides in sugar beets without significant sugar beetinjury. No injury was observed with preemergence applications of Dual Magnum in thistrial. However, in other sugar beet production regions, under extremely wet conditions,Dual Magnum has caused sugar beet injury when applied preemergence. In 2004,weather conditions were favorable and maximized the weed control provided bypostemergence herbicide treatments. Under different environmental conditions, DualMagnum or Outlook may have provided increased levels of broadleaf weed control.Besides helping control annual weeds, both Dual Magnum and Outlook are effective insuppressing yellow nutsedge in sugar beet.

200

Table 1postemStation,

Treatment

. WeedergenceOregon

control in sugar beet with standard rate herbicide treatments includingapplications of Outlook® and Dual Magnum®, Malheur ExperimentState University, Ontario, OR, 2004.

Weed controlt

Pigweed Lambs- Hairy Barnyard-Rate Timing* Kochia Spp. quarters nghtshade grass

oz ai/acre 0/

Untreated control

Progress + UpBeetProgress + UpBeet + StingerProgress + UpBeet + Stinger +Dual Magnum

Progress + UpBeetProgress + UpBeet + Stinger +OutlookProgress + UpBeet + Stinger

Progress + UpBeetProgress + UpBeet + Stinger +Outlook + TreflanProgress + UpBeet + Stinger

Progress + UpBeetProgress + UpBeet + StingerProgress + UpBeet + Stinger +Outlook

4.0 + 0.255.4+0.25+1.5

6.7 + 0.25 + 1.5 +15.3

23

4.0 + 0.25 1

5.4+0.25+1.5+ 213.4

6.7+0.25+1.5 3

4.0 + 0.25 1

5.4+0.25+1.5+ 213.4 + 8.0

6.7+0.25+1.5 3

4.0 + 0.25 1

5.4+0.25+1.5 26.7+0.25+1.5+ 3

13.4

100 100 100 100 98

Progress + UpBeetProgrees + UpBeet + Stinger +Dual Magnum + TreflanProgress + UpBeet + Stinger

LSD (0.05)

4.0 + 0.255.4 + 0.25 + 1.5 +

15.3 + 8.06.7 + 0.25 + 1.5

1

2

3

100 100 100 100 98

-- NS NS NS NS 6

201

Progress + UpBeet +Dual MagnumProgress + UpBeet + Stinger +Dual MagnumProgress + UpBeet + Stinger

4.0 + 0.25 +15.3

5.4 + 0.25 + 1.5 +15.3

6.7 + 0.25 + 1.5

1

2

3

100 100 100 100 100

Progress + UpBeetProgress + UpBeet + Stinger +Dual MagnumProgress + UpBeet + Stinger

4.0 + 0.255.4 + 0.25 + 1.5 +

15.36.7 + 0.25 + 1.5

1

23

100 100 100 100 97

Progress + UpBeetProgress + UpBeet + Stinger +Dual MagnumProgress + UpBeet + Stinger +Dual Magnum

4.0 + 0.255.4 + 0.25 + 1.5 +

15.36.7 + 0.25 + 1.5 +

15.3

1

2

3

100 100 100 100 100

Dual MagnumProgress + UpBeetProgress + UpBeet + Stinger +Dual MagnumProgress + UpBeet + Stinger

20.34.0 + 0.25

5.4 + 0.25 + 1.5 +15.3

6.7 + 0.25 + 1.5

PRE1

2

3

100 100 100 100 100

Progress + UpBeetProgress + UpBeet + StingerProgress + UpBeet + Stinger

4.0 + 0.255.4 + 0.25 + 1.56.7 + 0.25 + 1.5

1

23

99 100 100 100 84

Dual MagnumProgress + UpBeetProgress + UpBeet + StingerProgress + UpBeet + Stinger

20.34.0 + 0.25

5.4 + 0.25 + 1.56.7 + 0.25 + 1.5

PRE1

23

100 100 100 100 100

100 100 100 100 100

100 100 100 100 100

100 100 100 100 98

*Application timings were (PRE) April 13, (1) April 26 to cotyledon beets, (2) May 3 to 2- to 4-leaf beets, and (3) May 14 to 6- to 10-leaf beets.tWeed control was evaluated October 8 and 9. Pigweed species included Powell amaranth and redroot pigweed.

Table 2. SugarpostemergenceStation, Oregon

beet injury and yield with standardapplications of Outlook® andState University, Ontario, OR,

rate herbicideDual Magnum®,

2004.

treatments includingMalheur Experiment


oz ai/acre

Sugar beet

Injury Yieldt

5-10 6-9

0/

Rootyield

ton/acre

Sucrose Extraction

0/

ERS

lbs/acre

Untreated control -- -- -- -- 11.9 17.4 93.4 3,901

Progress + UpBeet + 4.0 + 0.25 + 1 24 9 46.0 17.5 93.6 15,019Dual Magnum 15.3Progress + UpBeet + Stinger + 5.4 + 0.25 + 1.5 + 2Dual Magnum 15.3Progress + UpBeet + Stinger 6.7 + 0.25 + 1.5 3

Progress + UpBeet 4.0 + 0.25 1 27 13 43.0 16.8 93.4 13,594Progress + UpBeet + Stinger + 5.4 + 0.25 + 1.5 + 2Dual Magnum 15.3Progress + UpBeet + Stinger 6.7 + 0.25 + 1.5 3

Progress + UpBeet 4.0 + 0.25 1 21 20 44.1 17.0 93.4 14,053Progress + UpBeet + Stinger + 5.4 + 0.25 + 1.5 + 2Dual Magnum 15.3Progress + UpBeet + Stinger + 6.7 + 0.25 + 1.5 + 3Dual Magnum 15.3Dual Magnum 20.3 PRE 35 20 41.8 17.3 93.7 13,506Progress + UpBeet 4.0 + 0.25 1

Progress + UpBeet + Stinger + 5.4 + 0.25 + 1.5 + 2Dual Magnum 15.3Progress + UpBeet + Stinger 6.7 + 0.25 + 1.5 3

Progress + UpBeet 4.0 + 0.25 1 25 11 44.3 17.8 93.7 14,717Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5 2Progress + UpBeet + Stinger 6.7 + 0.25 + 1.5 3

Dual Magnum 20.3 PRE 31 16 42.1 17.2 93.4 13,552Progress + UpBeet 4.0 + 0.25 1

Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5 2Progress + UpBeet + Stinger 6.7 + 0.25 ÷ 1.5 3

Progress + UpBeet 4.0 + 0.25 1 27 13 44.4 17.1 93.4 14,191Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5 2Progress + UpBeet + Stinger + 6.7 + 0.25 + 1.5 + 3Dual Magnum 15.3

Progress + UpBeet 4.0 + 0.25 1 30 24 43.0 17.3 94.5 13,902Progress + UpBeet + Stinger + 5.4 + 0.25 + 1.5 + 2Outlook 13.4Progress + UpBeet + Stinger 6.7 + 0.25 + 1.5 3

Progress + UpBeet 4.0 + 0.25 1 29 10 43.8 17.3 93.6 14,187Progress + UpBeet + Stinger + 5.4 + 0.25 + 1.5 + 2Outlook + Treflan 13.4 + 8.0Progress + UpBeet + Stinger 6.7 + 0.25 + 1.5 3

Progress + UpBeet 4.0 + 0.25 1 30 15 40.9 17.1 93.5 13,063Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5 2Progress + UpBeet + Stinger + 6.7 + 0.25 + 1.5 + 3Outlook 13.4

Progress + UpBeet 4.0 + 0.25 1 24 10 45.2 17.6 93.7 14,917Progrees + UpBeet + Stinger + 5.4 + 0.25 + 1.5 + 2Dual Magnum + Treflan 15.3 + 8.0Progress + UpBeet + Stinger 6.7 + 0.25 -I- 1.5 3

LSD (0.05) -- NS NS 6.6 NS NS 2,283

0Application timings were (PRE) April 13, (1) April 26 to cotyledon beets, (2) May 3 to 2-to 4-leaf beets, and (3) May 14 to 6-to 10-leaf beets.tSugar beets were harvested on October 8 and 9. ERS = estimated recoverable sucrose.

202

COMPARISON OF CALENDAR DAYS AND GROWING DEGREE-DAYS FORSCHEDULING HERBICIDE APPLICATIONS IN SUGAR BEET


Oregon State. UniversityOntario, OR, 2004

Introduction

Timely herbicide application is critical to achieve effective weed control in sugar beet.Often, the amount of time between sequential herbicide applications is based on agiven number of calendar days since the prior herbicide application. Under mostcircumstances this approach works well. When spring weather is cooler than normal,applying herbicides on a calendar day schedule may result in applications too closetogether. This can result in greater injury to the beets or herbicides being appliedbefore they are needed. Since weed and beet growth depend on temperature, it islogical that using accumulated growing degree-days (GDD) to schedule herbicideapplications may be superior to calendar days. GDD accounts for variations in theweather and gives a more accurate idea of how fast plants are growing. If the weatheris ideal for weed and beet growth, herbicide applications are made closer together; ifthe weather is cool, then applications are spaced further apart. Evaluation of a GDDmodel for timing herbicide applications may provide producers with a tool to improve theefficacy of the herbicides they are using.

Methods

A trial was established at the Malheur Experiment Station under furrow irrigation onApril 8, 2004. Sugar beets (Hilleshog 'PM-21') were planted in 22-inch rows at 2-inchseed spacing. On April 9, the trial was corrugated and Counter 20 CR® was applied ina 7-inch band over the row at 6-ozIl 000 ft of row. Sugar beets were thinned to an 8-inch spacing on May 10 to 13. Plots were sidedressed on June 2 with 175 lb nitrogen(N) (urea), 30 lb potash (1(20), 35 lb sulfates (SO4), 38 lb elemental sulfur (S), 3 lbmanganese (Mn), 2 lb zinc (Zn), and I lb/acre boron (B). All plots were treated withRoundup® lb ai/acre) on April 13 prior to sugar beet emergence. On May 26,Temik 15GR (14 lb prod/acre) was applied for sugar beet root maggot control. Poast®at 16 oz/acre plus crop oil concentrate at I qt/acre were applied to the trial area onJune 16. For powdery mildew control, Headline® (12 fI oz/acre) was applied on June25, Topsin M® (20 oz prod/acre) plus S at 6 lb/acre, phosphate (P205) at 1.5 lb/acre,and Zn at 0.2 lb/acre were applied on August 4, and Headline® (12 fI oz/acre) plus S at6 lb/acre were applied on August 8. All fungicide treatments were applied by air.Herbicide treatments were broadcast applied with a C02-pressurized backpack sprayercalibrated to deliver 20 gal/acre at 30 psi. Plots were 4 rows wide and 27 ft long andtreatments were arranged in a randomized complete block design with 4 replicates.

203

Standard rate, increased standard rate, and micro-rate treatments were comparedwhen applied on fixed calendar day schedules or when applied on different GDDaccumulation schedules. The standard and high-standard-rate treatments were appliedevery 7 or 10 days and these timings were compared to applications at 150, 175, or 225accumulated GDD since the previous application. The micro-rate treatments wereapplied on a 5- or 7-day schedule or at 150, 175, or 225 GDD since the previousapplication. Growing degree-days were calculated on a base of 34°F using theequation GDD = [(daily high temperature — daily low temperature)/2] — 34. GDD werecalculated beginning the day after each herbicide application. Herbicide applicationdates and GDD measured between applications are shown in Table 1.

Table 1. Application dates for herbicide treatments applied to sugar beet on calendarday or growing degree-day (GDD) schedules, Malheur Experiment Station, Ontario, OR,2004.

Treatment* TimingtApplication

PRE 1st 2nd 3rd 4thCalendar date (GDD since previous application)

Standard/High Rate 7 Day 4/13 4/26 5/3 5/10 --

Standard/High Rate 10 Day 4/13 4/26 5/6 5/16 --

Standard/High Rate 150 GDD 4/13 4/26 5/3 (151) 5/10 (199) --

Standard/ High Rate 175 GDD 4/13 4/26 5/4 (187) 5/12 (173) --

Standard/High Rate 225 GDD 4/13 4/26 5/6 (252) 5/17 (228) --

Micro-rate 5 Day 4/13 4/23 4/29 5/4 5/9Micro-rate 7 Day 4/13 4/23 5/1 5/8 5/15Micro-rate 150 GDD 4/13 4/23 5/1 (152) 5/7 (164) 5/15 (153)Micro-rate 175 GDD 4/13 4/23 5/2 (180) 5/9 (206) 5/22 (201)Micro-rate 225 GDD 4/13 4/23 5/4 (249) 5/12 (220) 5/26 (228)

*Standard and high-standard-rate treatments were applied on the same dates.tApplication timing based on GDD were determined by calculating the number of GDD beginning the dayafter the previous application, using the equation GDD = [(daily high temperature — daily lowtemperature)/2} — 34.

Sugar beet injury was evaluated on May 29 and June 9, and weed control wasevaluated on September 3. Sugar beet yields were determined by harvesting thecenter two rows of each plot on October 8 and 9. Root yields were adjusted to accountfor a 5 percent tare. One sample of 16 beets was taken from each plot for qualityanalysis. The samples were coded and sent to Syngenta Seeds Research Station inNyssa, Oregon, to determine beet pulp sucrose content and purity. Sucrose contentand recoverable sucrose were estimated using empirical equations. Data wereanalyzed using analysis of variance procedures and means were separated usingprotected LSD at the 95 percent confidence interval (P = 0.05). The untreated controlwas not included in the analysis of variance for weed control or crop response.

204


For the standard and high-rate herbicide treatments, the number of days betweenherbicide applications was the same for the 7-day schedule and the 1 50-GDDschedule. Applications on the 10-day schedule were within a day of the applicationsbased on 225 GDD. The 175-GDD-spray schedule was between the other schedules.The final application of the standard and high rate herbicide treatments varied by asmuch as 7 days between application schedules. For micro-rate treatments, the 5-dayapplication schedule was shorter than all other application schedules with the finalapplication made by May 9. The 7-day application timing was almost the same as thetiming based on 150-GDD. Applications based on 175 GDD were generally ito 7 dayslater than the I 50-GDD schedule and applications with the 225-GDD schedule werelikewise delayed 2 to 4 days compared to 175 GDD. The final application date amongthe different application schedules varied by as much as 17 days. In different years,the GDD application schedules could be significantly different from the fixed dayapplication timings, depending on the weather patterns.

Postemergence treatments were very effective this year and timing had little effect onweed control. Pigweed and common lambsquarters control were reduced when themicro-rate was applied on a 225-GDD interval compared to all other treatments (Table2). All other treatments and timings provided 94 percent or higher control of pigweed,common lambsquarters, hairy nightshade, kochia, and barnyardgrass. It is surprisingthat such a wide range of application timings could produce such complete control of allspecies. Since the standard rate was so effective, no differences were observedbetween the standard rate and the high-standard-rate treatments.

On May 24, injury from the standard or high-standard-rate treatments was among thegreatest with the I 75-GDD-application timing (Table 3). This does not appear to berelated to the interval between herbicide applications, but seems to be related to rainfallevents preceding those herbicide applications. There was no difference in sugar beetinjury among the micro-rate treatments. By June 9, there were no differences in sugarbeet injury between any of the herbicide treatments or application timings.

All herbicide treatments increased sugar beet root yield and estimated recoverablesugar compared to the untreated check (Table 3). There were no differences in percentextraction or sugar content for any treatment. Root yields were not different among theherbicide treatments and application timings. The high rate applied on a 10-day intervalproduced more estimated recoverable sucrose than the standard rate applied on thesame 10-day schedule or the micro-rate applied on the 225-GDD-application schedule.

This year application timing was not critical because the postemergence treatmentsworked very well. In addition, the initial postemergence applications were made at thecorrect time while weeds were small. If the initial timing is delayed, the time betweensubsequent applications may be much more critical.

205

Table 2. Weed control in sugar beet with standard rate, high-standard-rate, and micro-rate herbicide treatments applied on a calendar day schedule or at different growingdegree-day (GDD) intervals, Maiheur Experiment Station, Ontario, OR, 2004.

Treatment* Rate

Weed controlt

Pigweed Common Hairy BarnyardTimingt spp. lambsguarters nightshade Kochia -grass

ozai/acreor%v/v -- 0/

Standard RateProgress + UpBeet 4.0 + 0.25Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5Progress + UpBeet + Stinger 5.4 + 0.25 + 1.5

7 Day 99 100 100 100 96

Standard Rate Same as above

Standard Rate Same as above

10 Day 97 100 100 100 98

150 ODD 100 100 100 100 100

Standard Rate Same as above 175 GDD 100 100 100 100 100Standard Rate Same as above 225 ODD 99 100 100 100 97

Micro-RateProgress + UpBeet + Stinger 1.3 + 0.08 + 0.5+MSQ +1.5%v/vProgress + UpBeet + Stinger 1.3 + 0.08 + 0.5+MSO +15%v/vProgress + UpBeet + Stinger 2.0 + 0.08 + 0.5+MSO +15%v/vProgress + UpBeet + Stinger 2.0 + 0.08 + 0.5+MSO +15%v/v

5 Day 96 99 100 99 98

Micro-Rate Same as above 7Day 96 100 100 100 100Micro-Rate Same as above 150 ODD 94 98 100 98 100Micro-Rate Same as above 175 ODD 98 99 100 100 100Micro-Rate Same as above 225 ODD 86 93 100 98 99High RateProgress + UpSeet 4.0 + 0.25Progress + UpBeet ÷ Stinger 6.7 + 0.37 + 1.5Progress + UpBeet÷ Stinger 8.1 + 0.5 + 1.5

7 Day 100 100 100 100 98

High Rate Same as above 10 Day 98 100 100 100 98HighRate Same as above 150 ODD 100 100 100 100 100

HighRate Same as above 175 GDD 99 100 100 100 100HighRate Same as above 225 ODD 100 100 100 100 100LSD (P = 0.05) -- -- 4 2 NS NS NS

*Standard and high-standard-rate treatments were applied on the same dates.tApplication timing based on GDD were determined by calculating the number of ODD beginning the day after the previousapplication using the equation ODD = [(daily high temperature — daily low temperature)/21 —34.tWeed control was evaluated September 3. Pigweed species are a mixture of redroot pigweed and Powell amaranth.

206

Untreated control

Standard RateProgress + UpBeetProgress + UpBeet + StingerProgress + UpBeet + Stinger

Standard Rate

Standard Rate

Standard Rate

Standard Rate

Micro-RateProgress + UpBeet + Stinger+ MSOProgress + UpBeet + Stinger+ MSOProgress + UpBeet + Stinger+ MSOProgress + UpBeet + Stinger+ MSO

Micro-Rate

Micro-Rate

Micro-Rate

Micro-Rate

High RateProgress + UpBeetProgress + UpBeet + StingerProgress + UpBeet + Stinger

High Rate

High Rate

High Rate

High Rate

LSD (P = 0.05)

Table 3. Sugar beet injury and yield with standard rate, high-standard-rate, andrate herbicide treatments applied on a calendar day schedule or at differentdegree-day (GDD) intervals, Maiheur Experiment Station, Ontario, OR, 2004.

micro-growing

Sugar beets

Injury Yield

Treatment* Rate Timingt 5-24 6-9 Root yield Extraction Sucrose ERS

-- 0/oz ai/acre or % v/v ton/acre

6.6

7Day 14 11 45.2

0/

93.7 17.0

lbs/acre

2,119

93.1 16.6 14,001

10 Day 21 14

15OGDD 11 8

175GDD 26 11

225 GDD 14 10

93.4

93.4

93.4

93.3

16.9

16.6

16.4

16.8

13,422

14,822

14,141

14,409

42.6

47.7

46.0

46.0

8 11 46.9

15 13 46.6

17 11 45.6

11 9 44.3

9 10 42.5

4.0 + 0.255.4 + 0.25 + 1.55.4 + 0.25 + 1.5

Same as above

Same as above

Same as above

Same as above

1.3 + 0.08 + 0.5+ 1.5% v/v

1.3 + 0.08 + 0.5+ 1.5% v/v

2.0 + 0.08 + 0.5+ 1.5% v/v

2.0 + 0.08 + 0.5+ 1.5% v/v

Same as above

Same as above

Same as above

Same as above

4.0 + 0.256.7 + 0.37 + 1.58.1 + 0.5 + 1.5

Same as above

Same as above

Same as above

Same as above

93.2 16.7 14,5685 Day

7 Day

150 GDD

175 GDD

225 GDD

93.1

93.1

93.3

93.4

16.8

16.7

16.7

16.9

14,532

14,195

13,823

13,398

7Day 19 6 47.3 93.4 16.3 14,396

10 Day

150 GDD

175 GDD

225 GDD

21 10 47.1

20 13 46.5

34 19 44.3

11 3 46.4

9 NS 4.4

93.9

93.3

93.6

93.3

NS

17.2

17.1

16.9

16.6

NS

15,231

14,852

14,019

14,334

1,459

*Standard and high standard rate treatments were applied on the same dates.tApplication timing based on GDD were determined by calculating the number of GDD beginning the day after the previousapplication using the equation GDD = [(daily high temperature — daily low temperature)/2] — 34.tSugar beets were harvested October 8 and 9. ERS = estimated recoverable sucrose.

207

2004 WINTER ELITE WHEAT TRIAL

Eric P. Eldredge, Clinton C. Shock, and Lamont D. SaundersMalheur Experiment Station


Introduction

Maiheur Experiment Station provides one location for the Oregon State UniversityStatewide Winter Elite Wheat variety-testing program. This location compares cerealgrain variety performance in a furrow-irrigated, high potential yield environment. Plantbreeders can use information on variety performance to compare advanced lines withreleased cultivars. Growers can use this information to make decisions about which softwhite winter wheat varieties may perform best in their fields.

Methods

The previous crop was sweet corn. After harvest, the corn stalks were flailed, the fieldwas disked, and the soil was sampled and analyzed. The analysis showed 138 lbnitrogen (N), 80 lb available phosphate (P205), 1,478 lb soluble potash (1(20), and 70 lbsulfate (S04)/acre in the top 2 ft of soil, with 2,361 ppm calcium (Ca), 443 ppmmagnesium (Mg), 107 ppm sodium (Na), 1.7 ppm zinc (Zn), 26 ppm iron (Fe), 7 ppmmanganese (Mn), 0.6 ppm copper (Cu), 0.8 ppm boron (B), pH 7.6, and 3.2 percentorganic matter in the top foot of soil. Pre-plant fertilizer was a broadcast application onOctober 7, 2003 of 97 lb N/acre, 5 lb Cu/acre, and 1 lb B/acre. The soil was deepripped, plowed, and groundhogged to prepare the seedbed. The field was corrugatedinto 30-inch rows.

The Winter Elite Wheat Trial was comprised of 40 soft white winter wheat cultivars orlines, 3 of which were club head types. Seed of all entries was treated with fungicideand insecticide seed treatment prior to planting. Grain was planted at 30 live seed/ft2,corresponding to a seeding rate of approximately 110 lb/acre. The experimental designwas a randomized complete block with three replications. Grain was planted on October17, 2003, with a small plot grain drill, into plots 5 by 20 ft, and then the field wasrecorrugated. The field was partially furrow irrigated on November 11 to promoteemergence. The irrigation had to be stopped because the runoff water was interferingwith irrigation district repairs.

A soil sample was taken from the field on April 2, 2004. The soil analysis showedammonia and nitrate forms of N in the top 2 ft of soil totaled 86 lb N, with 38 lbextractable P2O5, 861 lb available 1(20, 83 lb S04/acre in the top 2 ft of soil, with 12ppm Ca, 370 ppm Mg, 108 ppm Na, 1.2 ppm Zn, 2 ppm Fe, 1 ppm Mn, 0.5 ppm Cu, Ippm B, pH 7.7, and 3.2 percent organic matter. Urea prills fertilizer (95.6 lb N/acre) was

208

broadcast over the trial on March 30, 2004. This application was an error. Broadleafweeds were controlled with Bronate® at lqt/acre applied on May 3. On May 20, fertilizerwas broadcast to supply 13 lb N/acre, 60 lb P205/acre, 3 lb Zn/acre, and 1 lb Cu/acre.The field was furrow irrigated for 24 hours on April 9, May 5, and June 3. Observationsof heading date were started on June 4, after 100 percent heading had alreadyoccurred in many varieties. Heading date observations should have started in May.Alleys 5 ft wide were cut with a Hege small plot combine on July 21. The length of eachplot was measured and recorded after the alleys were cut, and the plots were harvestedon July 21 with a Hege small plot combine.

Results

The grain plants in the Winter Elite Wheat Trial grew very lush, with lodging alreadyobserved on May 20, before heading. A thunderstorm brought 0.41 inch of rain andstrong winds on May 18, followed by 0.89 more inches of rain in storms with wind overthe following 10 days, contributing to the lodging that was observed. Plant height atmaturity could not be measured in the trial this year because of extensive lodging. Theresidual nitrate plus ammonium in the fall of 2003 was substantial, and the trial receivedtoo much N fertilizer during its growth and development.

Among the soft white winter wheat varieties, the highest yielding was 'ORHOIO918' at115 bushel/acre, which was not significantly (at LSD 0.05) higher than other entries inthis trial (Table 1). Due to the heavy lodging observed, the trial is useful to comparevariety resistance to lodging. 0RH010918 was the only entry to show no lodging atharvest, suggesting that it may have exceptional straw strength, similar to 'ORCF-lOt,'ORHOl 1483', '0RH010920', 'CODA', '0R12020015', '0R9901887', 'MEL1, 'SIMON','CLEARFIRST', and '0R9900513', which were among the least severely lodged entriesin this trial.

209

Table 1. Winter Elite Wheat Trial entries, market class, lodging, and yield,Maiheur Experiment Station, Oregon State University, Ontario, OR, 2005.

Market Origin orEntry Variety class develoDer %

37 ORHOIO918 SWW OSU 0 115.31 STEPHENS SWW OSU 57 114.3

31 OR9901887 SWW OSU 43 113.225 OR9801757 SWW OSU 97 107.423 0R3970965 SWW OSU 90 106.640 0RH011483 SWW OSU 17 106.339 0RH011481 SWW OSU 60 105.910 DUNE SWW Uofl 60 105.3

3 GENE SWW OSU 60 105.238 ORHO1O92O SWW OSU 30 103.8

9 SIMON SWW Uofl 47 102.436 OR2010353 SWW OSU 100 99.519 ORCF-101 SWW-Clearfield OSU 3 98.8

8 BRUNDAGE96 SWW U of I 67 98.626 OR9900553 SWW OSU 67 97.114 CODA Club ARS-WSU 37 96.633 OR2010239 SWW OSU 67 95.735 OR2010242 SWW OSU 90 95.0

7 ROD SWW WSU 97 94.621 0RI2020015 SWW-Clearfielcj OSU 40 93.420 OR12010007 SWW-Clearfjeld OSU 67 93.218 IDO587CL SWW-Clear-field U of I 70 91.811 SWW U of I 57 89.517 CLEARFIRST SWW-Clearfield Gen. Mills 50 89.334 OR2010241 SWW OSU 83 88.528 OR9900598 SWW OSU 90 88.0

4 WEATHERFORD SWW OSU 93 87.716 MEL Club-Clearfield Gen. Mills 43 87.26 FINCH SWW ARS-WSU 63 85.4

30 OR9900513 SWW OSU 50 85.424 OR9801695 SWW OSU 80 84.313 WESTBRD528 SWW Westbred 90 83.2

2 MADSEN SWW ARS-WSU 80 80.832 OR9901619 SWW OSU 90 80.1

5 TUBBS SWW OSU 97 78.229 0R9900547 SWW OSU 93 75.115 CHUKAR Club ARS-WSU 57 74.512 MOHLER SWW Westbred 100 64.427 OR9900548 SWW OSU 100 63.822 OR941611 SWW OSU 70 63.2

*Adjusted to 10% moisture,= Not Significant.

Mean 66.3 92.2LSD (0.05) 52.1

lb/bushel.

210

AUTOMATIC COLLECTION, RADIO TRANSMISSION, AND USE OFSOIL WATER DATA1

Clinton C. Shock, Erik B. G. Feibert, Andre B. Pereira,and Cedric A. Shock

Oregon State UniversityMalheur Experiment Station

Ontario, OR, 2004

Abstract

Precise scheduling of drip irrigation has become very important to help assure optimumdrip-irrigated crop yield and quality. Soil moisture sensors have often been adopted toassure irrigation management. Integrated systems for using soil moisture data couldenhance widespread applicability. An ideal system would include the equipment tomonitor field conditions, radios to transmit the information from the field because wiresimpede cultivation and can complicate cultural practices, interpretation of soil waterstatus, and the equipment to automatically control irrigation systems.Key words: automation, irrigation scheduling, onion, A/hum cepa

Introduction

Onions (All/urn cepa) require frequent irrigations to maintain high soil moisture. Dripirrigation has become popular for onion production because a higher soil moisture canbe maintained without the negative effects associated with furrow irrigation. Dripirrigation can also be automated. Automated drip irrigation of onions has been used forirrigation management research at the Malheur Experiment Station since 1995 (Feibertet al. 1996; Shock et al. 1996, 2002). However, the extensive wiring impedescultivation and can complicate cultural practices. Several companies manufactureautomated irrigation systems designed for commercial use that use radio telemetry,reducing the need for wiring. This trial tested three commercial soil moisture monitoringsystems and compared their irrigation on onion performance to the research systembased on Campbell Scientific (Logan, UT) components currently used (Shock et al.2002).


The onions were grown at the Malheur Experiment Station (MES), Ontario, Oregon, onan Owyhee silt loam previously planted to wheat. Onion (cv. 'Vaquero', Nunhems,Parma, ID) was planted in 2 double rows, spaced 22 inches apart (center of double rowto center of double row) on 44-inch beds on March 17, 2004. The 2 rows in the doublerow were spaced 3 inches apart. Onion was planted at 150,000 seeds/acre. Drip tape

1 This report is provided as a courtesy to onion growers. This work was supported bysources other than the Idaho-Eastern Oregon Onion Committee.

211

(T-tape, T-systems International, San Diego, CA) was laid at 4-inch depth between the2 double onion rows at the same time as planting. The distance between the tape andthe center of the double row was 11 inches. The drip tape had emitters spaced 12inches apart and a flow rate of 0.22 gal/mm/i 00 ft.

Onion emergence started on April 2. The trial was irrigated with a minisprmnkler system(RiO Turbo Rotator, Nelson Irrigation Corp., Walla Walla, WA) for even standestablishment. Risers were spaced 25 ft apart along the flexible polyethylene hoselaterals that were spaced 30 ft apart.

Weed and insect control practices were similar to typical crop production standards andfertilizer applications were similar to common practices and followed therecommendations of Sullivan et al. (2001).

The experimental design was a randomized complete block with three replicates. Eachirrigation system was tested in 3 zones that were 16 rows by 50 ft long. There werefour automated irrigation systems tested. Each integrated system contained severaldistinctive parts, some automated and some requiring human input: soil moisturemonitoring, data transmission from the field, collection of the data, interpretation of thedata, decisions to irrigate, and control of the irrigation. Additionally, all data weredownloaded for evaluation of the system.

Campbell ScientificThe system currently used for research at MES uses a Campbell Scientific Inc. (Logan,UT) datalogger (CR1OX). Each zone had four granular matrix sensors (GMS,Watermark Soil Moisture Sensor Model 200SS, Irrometer Co. Inc., Riverside, CA) usedto measure soil water potential (SWP) (Shock 2003). The GMS from all three zoneswere connected to an AM416 multiplexer (Campbell Scientific), which in turn wasconnected to the datalogger at the field edge. The soil temperature was also monitoredand was used to correct the SWP calibrations (Shock et al., 1998a). The dataloggerwas programmed to monitor the soil moisture and controlled the irrigations for eachzone individually. The Campbell Scientific datalogger was programmed to makeirrigation decisions every 12 hours: zones were irrigated for 8 hours if the SWPthreshold was exceeded. The Campbell Scientific datalogger used an average soilwater potential at 8-inch depth of-20 kPa or less as the irrigation threshold. Thedatalogger controlled the irrigations using an SDM 16 controller (Campbell Scientific) towhich the solenoid valves at each zone were connected. Data were downloaded fromthe datalogger with a laptop computer or with an SM192 Storage Module (CampbellScientific) and a CR1OKD keyboard display (Campbell Scientific). The datalogger waspowered by a solar panel and the controller was powered by 24 V AC. The CampbellScientific system was started on May 15, 2004.

AutomataAutomata, Inc. (Nevada City, CA) manufactures dataloggers, controllers, and softwarefor data acquisition and process control. Each one of the three zones had four GMSconnected to a datalogger (Mini Field Station, Automata). The dataloggers at each

212

zone were connected to a controller (Mini-P Field Station, Automata) at the field edgeby an internal radio; The controllers were connected to a base station (Mini-P BaseStation, Automata) in the office by radio. The base station was connected to a desktopcomputer. Each zone was irrigated individually using a solenoid valve. The solenoidvalves were connected to and controlled by the controller. The desktop computer ranthe software that monitored the soil moisture in each zone and made the irrigationdecisions every 12 hours: zones were irrigated for 8 hours if the SWP threshold wasexceeded. The irrigation threshold was the average SWP at 8-inch depth of -20 kPa orless. The Mini Field Stations were powered by solar panels and the Mini-P FieldStation was powered by 120 V AC. The Automata system was started on June 24,2004.

Watermark MonitorIrrometer manufactures the Watermark Monitor datalogger that can record data fromseven GMS and one temperature probe. The soil temperature is used to correct theSWP calibrations. Each of the three Watermark Monitor zones had seven GMSconnected to a Watermark Monitor. Data were downloaded from the WatermarkMonitor both by radio and with a laptop computer. The Watermark Monitors werepowered by solar panels. Irrigation decisions were made daily by reading the GMSdata from each Watermark Monitor. When the SWP reached -20 kPa the zone wasirrigated manually for 8 hours. The Watermark Monitors were started on May 15, 2004.

AcclimaAcclima (Meridian, ID) manufactures a Digital TDTTM that measures volumetric soilmoisture content. Each zone had one TDT sensor and four GMS. The TDT sensorswere connected to a model CS3500 controller (Acclima) at the field edge. Thecontroller monitored the soil moisture and controlled the irrigations for each zoneseparately using solenoid valves. The controller was powered by 120 V AC. Data wasdownloaded from the controller using a laptop computer. For comparison andcalibration, the GMS were connected to the Campbell Scientific datalogger whichmonitored the soil water potential as described above. The Acclima system was startedon May 16. The CS3500 controller was programmed to irrigate the zone when thevolumetric soil water content was equal to or lower than 27 percent. The soil waterpotential data was compared to the volumetric soil water content data to adjust theCS3500 controller to irrigate each zone in a manner equivalent to the irrigationscheduling using the GMS (Fig. 1). Due to excessive soil moisture, on June lithelower threshold at which irrigations were started was changed from 27 percent to 19percent, and 21 percent for Acclima zones one and two, respectively, to correspond to-20 kPa soil water potential. When installed, due to a software constraints, thecontroller could only water a maximum of 4 hours at each irrigation. On July 21 thesoftware was upgraded allowing irrigation durations to be increased to 8 hours. Giventhe flow rate of the drip tape, 8 hour irrigations applied 0.48 inches of water. Previousresearch indicates that the ideal amount of water to apply at each irrigation is 0.5inches (Shock et al., 2004).

213

All soil moisture sensors in every zone of the four systems were installed at 8-inchdepth in the center of the double onion row. The GMS were calibrated to SWP (Shocket al. 1998). The Campbell Scientific, Acclima, and Automata controllers wereprogrammed to make irrigation decisions every 12 hours: zones were irrigated for8hours if the soil moisture threshold was exceeded. The Campbell Scientific andAutomata dataloggers used an average soil water potential at 8-inch depth of -20 kPaor less as the irrigation threshold. The Irrometer zones also had a threshold of -20 kPa.The amount of water applied to each plot was recorded daily at 8:00 a.m. from a watermeter installed downstream of the solenoid valve. The total amount of water appliedincluded sprinkler irrigations applied after emergence and water applied with the dripirrigation system from emergence through the final irrigation.

Onion evapotranspiration (ETa) was calculated with a modified Penman equation(Wright 1982) using data collected at the Malheur Experiment Station by an AgriMetweather station (U.S. Bureau of Reclamation, Boise, Idaho). Onion was estimatedand recorded from crop emergence until the final irrigation on September 2.

On September 24 the onions were lifted to field cure. On September 27, onions in thecentral 40 ft of the middle four double rows in each zone were topped and bagged. OnSeptember 28 the onions were graded. Bulbs were separated according to quality:bulbs without blemishes (No. is), double bulbs (No. 2s), neck rot (bulbs infected withthe fungus Botrytis al/il in the neck or side), plate rot (bulbs infected with the fungusFusarium oxysporum), and black mold (bulbs infected with the fungus Aspergi//usniger). The No. 1 bulbs were graded according to diameter: small (<21,4 inch), medium(2% to 3 inch), jumbo (3 to 4 inch), colossal (4 to 4% inch), and supercolossal (>414inch). Bulb counts per 50 lb of supercolossal onions were determined for each zone ofevery variety by weighing and counting all supercolossal bulbs during grading.

Differences in onion performance and water application among irrigation systems weredetermined by protected least significant differences at the 95 percent confidence levelusing analysis of variance (Hintze, 2000).


Marketable onion yield was excellent, averaging 1,041 cwt/acre (116.6 Mg/ha) over the4 drip irrigation systems (Table 1). The average onion bulb yield in the Treasure Valleywas 625 cwt/acre (70.0 Mg/ha) in 2000, 630 cwt/acre (70.6 Mg/ha) in 2001, and 645cwt/acre (72.2 Mg/ha) in 2002 (USDA 2003). The excellent onion performance with allthe systems used was consistent with the maintenance of SWP within the narrow rangerequired by onion (Shock et al. i998b, 2000).

A comparison of the systems in terms of onion yield and grade is not completelyjustified because the systems were started at different times. In addition, the Acclimaand Automata systems required adjustments and modifications after the start ofoperation.

214

The Acclima system resulted in among the lowest marketable yield and yield of colossalbulbs. The Acclima system maintained the soil very wet at the beginning of the seasondue to our lack of knowledge of the appropriate volumetric soil water content thatcorresponded to ideal SWP (Figs. 2 and 3). After changes were made to the irrigationthreshold for each Acclima zone separately (Fig. 1), the soil volumetric water content(Fig. 3) was very stable with some seasonal deviations from the target SWP of -20 kPa(Fig. 2). Due to initial software limitations, the Acclima system had irrigation durationsof 4 hours until July 21. After July 21 the software was upgraded and the irrigationdurations were increased to 8 hours. Irrigation durations of less than 8 hours havebeen shown to reduce onion yield (Shock et al. 2004). Also, early heavy irrigation couldhave leached nitrate needed for optimal onion growth.

The Campbell Scientific and Automata maintained the SWP relatively constant andclose to the target of -20 kPa (Fig. 4). The lrrometer Watermark Monitors maintainedthe SWP on target, but with larger oscillations than the other systems, due to humancollection of the SWP data and human control of irrigation onset and duration (Fig. 4).

Water applications over time followed during the season (Fig. 5). The total waterapplied plus precipitation from emergence to the end of irrigation on September 2 was31.5, 40.0, 43.9, and 36.2 inches (800, 1,016, 1,115, and 919 mm) for the CampbellScientific, Irrometer, Automata, and Acclima systems, respectively. Precipitation fromonion emergence until irrigation ended on September 2 was 3.88 inches (99 mm).Onion evapotranspiration for the season totaled 30.9 inches (785 mm) from emergenceto the last irrigation. The Automata system used a new version of software that hadinitial bugs to work out. The Acclima system over-applied water when first installed,until the irrigation thresholds were adjusted downwards.

Conclusions

All the systems tested performed well in this preliminary evaluation. Onion yield, grade,and quality were excellent. Any small shortcomings in precise irrigation may have beendue to our unfamiliarity and inexperience using these systems.

References

Feibert, E.B.G., C.C. Shock, and L.D. Saunders. 1996. Plant population fordrip-irrigated onions. Oregon State University Agricultural Experiment Station SpecialReport 964:45-48.

Hintze, J.L. 2000. NCSS 97 Statistical System for Windows, Number CruncherStatistical Systems, Kaysville, Utah.

Shock, C.C., 2003. Soil water potential measurement by granular matrix sensors.Pages 899-903 in B.A. Stewart and l.A. Howell (eds.). The Encyclopedia of WaterScience. Marcel Dekker.

215

Shock, C.C., J. Barnum, and M. Seddigh. 1998a. Calibration of Watermark soilmoisture sensors for irrigation management. Pages 139-146 in Proceedings of theInternational Irrigation Show. Irrigation Association. San Diego, CA.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 1996. Nitrogen fertilization fordrip-irrigated onions. Oregon State University Agricultural Experiment Station SpecialReport 964:38-44.


Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2000. Irrigation criteria fordrip-irrigated onions. HortScience 35:63-66.

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2004. Irrigation frequency, drip tapeflow rate, and onion performance. Oregon State University Agricultural ExperimentStation Special Report 1055:58-66.

Shock, C.C., E.B.G. Feibert, L.D. Saunders, and E.P. Eldredge. 2002. Automation ofsubsurface drip irrigation for crop research. Pages 809-816 in American Society ofAgricultural Engineers, World Congress on Computers in Agriculture and NaturalResources. Iguacu Falls, Brazil.

Sullivan, D.M., B.D. Brown, C.C. Shock, D.A. Horneck, R.G. Stevens, G.Q. Pelter, andE.B.G. Feibert. 2001. Nutrient management for onions in the Pacific Northwest. PubI.PNW 546. Pacific Northwest Ext., Oregon State University, Corvallis, OR.

USDA. 2003. Vegetables 2002 Summary. Agricultural Statistics Board, NatI. Agric. Stat.Serv. Vg 1-2 (03): 32-34.

Wright, J.L.1982. New evapotranspiration crop coefficients. J. Irrig. Drain. Div. ASCE108:57-74.

216

Table 1. Onion yield and grade for a drip-irrigated onion field irrigated automatically byOregon State University Malheur Experiment Station, Ontario, OR 2004.four systems, -

System

Marketable yield by gradeTotal Total >4% in 4-4% in 3-4 in 2%-3 inyield

Super-colossalcounts

Nonmarketable yield

Total rot No. 2s Small

cwtlacre #/50 lb%oftotal -- cwt/acre --

Campbell Sci. 1035.9 1026.1 21.4 258.5 727.4 18.8 42.6 0.5 1,3 3.1

Irrometer 1081.4 1076.1 36.2 337.2 685.6 17.1 39.5 0.2 0.0 3.4Automata 1072.4 1064.0 18.2 306.0 724.6 15.2 41.8 0.4 1.5 2.2Acclima 1008.4 997.9 15.7 215.2 746.4 20.6 47.9 0.3 3.7 4.2Average 1049.5 1041.0 22.9 279.2 721.0 17.9 43.0 0.3 1.6 3.2LSD (0.05) 51.2 52.0 NS 86.5 NS NS

Mg/ha

NS

#/50 lb

NS

%oftotalyield

NS NS

--Mg/ha--

Campbell Sci. 116.0 114.9 2.4 29.0 81.5 2.1 42.6 0.5 0.2 0.4Irrometer 121.1 120.5 4.1 37.8 76.8 1.9 39.5 0.2 0.0 0.4Automata 120.1 119.2 2.0 34.3 81.2 1.7 41.8 0.4 0.2 0.3Acclima 112.9 111.8 1.8 24.1 83.6 2.3 47.9 0.3 0.4 0.5Average 117.5 116.6 2.6 31.3 80.8 2.0 43.0 0.3 0.2 0.4LSD (0.05) 5.7 5.8 NS 9.7 NS NS NS NS NS NS

217

0

a.

Y = -74.80 + 4.55X - 0.0782X2R2 = 0.35, P = 0.001

0 5 10 15 20 25 30

Volumetric soil water content, %

/21%

ii:= Y=-58.71 +1.77X

R2 = 0.45, P = 0.001

-400 5 10 15 20 25 30 35

Volumetric soil water content, %

27%

-30y = + 13.62- 2.79X + 0.0564X2

o R2=0.42,P=0.001(I)

-400 10 20 30 40 50

Volumetric soil water content. %

Figure 1. Regressions of volumetric soil water content from Acclima TDT sensorsagainst soil water potential from Watermark soil moisture sensors for each Acclima plot.Malheur Experiment Station, Oregon State University, Ontario OR.

218

0

0

Day of year

Figure 2. Soil water potential at 8-inch depth for a drip-irrigated onion field using theAcclima automated irrigation system with 3 irrigation thresholds, Oregon StateUniversity Malheur Experiment Station, Ontario, OR 2004.

0

-10

-20

-30

Irrigation-40 threshold 19%

-500

-10

-20

-30

-40

-500

-10

-20

-30

-40

-50135

Irrigationthreshold 21%

Irrigationthreshold 27%

161 187 213 239 265

219

30

20

Ca)C00a)

0U)

()

134 156

Ca)C0C)

a)Ca

0U)

C)

a)E

0>

Ca)

00a)

0U)

0

a)E:30>

Day of year

134 156 178 200

Day of year

40 --—----- ----— --- -

Irrigation threshold: 19%

178 200 222 244

Irrigation threshold: 21%

40

30

20

10

0 --

222 244

40

30-

20 -

10 -

Irrigation treshold: 27%

134 156 178 200 222 244

Day of year

Figure 3. Volumetric soil water content at 8-inch depth for a drip-irrigated onion fieldusing the Acclima irrigation system with 3 soil water content irrigation thresholds,Oregon State University, Maiheur Experiment Station, Ontario, OR 2004.

220

0

-10

-20

-30

265

-10ci)

o -20

-30

— 175 2650

-10

-20

-30

-40180 264

Day of year

Figure 4. Soil water potential at 8-inch depth for a drip-irrigated onion field using 3automated irrigation systems, Oregon State University Malheur Experiment Station,Ontario, OR 2004.

221

Campbell Scientific

161 187 213 239

Automata

193 211 229 247

Irrometer

201 222 243

40

30

20

U)10

U)00

c 40

30

20

10

90 245

Day of year

Figure 5. Water applied plus precipitation over time for drip-irrigated onions with 4automated irrigation systems. Thin line is water applied and thick line is EL, OregonState University Malheur Experiment Station, Ontario, OR 2004.

222

Campbell Scientific

I rrometer

Automata

Acclima

121 152 183 214

USE OF IRRIGAS® FOR IRRIGATIONSCHEDULING FOR ONION UNDER FURROW IRRIGATION

Andre B. Pereira, Clinton C. Shock, Cedric A. Shock,and Erik B.G. Feibert


Ontario, OR, 2004

Introduction

Irrigation scheduling consists of applying the right amount of water at the right time.Incentives to onion (A/hum cepa L.) growers for precise irrigation scheduling are basedon the fact that underirrigation leads to a loss in market grade, bulb quality, andcontract price, whereas overirrigation leads to a loss in water, electricity for pumping,leaching of nitrogen, and it may favor weeds and wastes labor. Overirrigation results insoil erosion, increases the potential for contamination of surface and groundwater, andrequires additional chemicals and fertilizers. One of the several tools growers can useto schedule irrigation is based on the monitoring of soil water potential (SWP) and acriterion has been established at —27 kPa for furrow-irrigated onion grown on silt loam(Shock et al. 1 998b). The SWP is of direct importance to plants because it reflects theforce necessary to remove water from the soil.

This trial had the following objectives: 1) to evaluate the performance of six differentkinds of soil moisture sensors in a furrow-irrigated onion field; 2) to compare theirrigation criterion of the Irrigas® to that defined by previous research carried out at theMalheur Experiment Station for onions under furrow irrigation; and 3) to verify if thenominal functioning pressure of the Irrigas performs reliably through wetting and dryingcycles on silt loam in eastern Oregon, and observe onion yield and quality.


Six types of soil moisture sensors were compared by their response to wetting anddrying in furrow-irrigated onion grown on Owyhee silt loam at the Malheur ExperimentStation. Seeds were planted on 17 March 2004 in double rows on 22-inch beds. Thedouble onion rows were spaced 3 inches apart. The sensors were tensiometers withpressure transducers (Irrometers, Irrometer Co. Inc., Riverside, CA, Model RA), ECH2Odielectric aquameter (Decagon Devices, Inc., Pullman, WA), granular matrix sensors(GMS, Watermark soil moisture sensors Model 200SS, Irrometer Co., Inc.), Irrigas(National Center for Horticultural Research of EMBRAPA, Brasilia, DF, Brazil), and twoexperimental granular matrix sensors not described further here. Sensors wereinstalled at 8-inch depth below the double row of onions on 15 July 2004 and replicateswere spread 60 ft apart down an irrigation furrow in a 3-acre field. The statistical designwas a randomized complete block with four replicates.

223

Tensiometers, GMS, and ECH2O dielectric aquameters were attached to three AM416multiplexers (Campbell Scientific, Logan, UT) that in turn were wired to a CR lOXdatalogger (Campbell Scientific), which was programmed to make readings once anhour. Two temperature sensors were installed at 8-inch depth to allow for temperaturecorrections of GMS readings. Data were collected from the datalogger using a laptopcomputer. Each replicate contained two tensiometers, two GMS, one ECH2O dielectricaquameter, and two Irrigas. The ECH2O dielectric aquameters were calibrated againstvolumetric soil water content by taking two soil samples near each probe centered at8-inch depth, once when the soil was relatively wet, and once when the soil wasrelatively dry, and by preparing oven-dry soil and placing the probes in the oven-dry soilat the end of the trial. Gravimetric data were converted to volumetric water contentsusing soil bulk density. Irrigas operates on the principle of air permeability of porousceramics explained below. Data were collected from all sensors from July 15 toSeptember 30, 2004.

Air permeability of porous ceramics has been used to estimate SWP (Kemper andAmemiya 1958). Air permeability of a specific porous ceramic is a function of its watercontent. As water dries from the ceramic, the pores allow the passage of air. The"initial bubbling pressure" (IBP) of a water-saturated porous ceramic is the lowestapplied pressure at which air permeability is observed.

The IBP of a specific porous ceramic can be used to estimate whether a soil hasreached a specific SWP used as an irrigation criterion. The National Center forHorticultural Research of EMBRAPA, Brazil used IBP to develop a SWP indicator,Irrigas (Calbo 2004; Calbo and Silva 2001). Irrigas consists of a porous ceramic cup, aflexible tube, a transparent barrel, a rigid thin plastic support, and a moveable containerof water. The porous ceramic cup is installed in the effective rooting zone of the cropand connected to a small transparent barrel by means of the flexible tube. The porousceramic cup is designed to retard free air movement out of the cup until the soil and cupreach a predetermined water potential. To make a reading, the barrel is immersed inthe container of water. The free air passage through the porous ceramic cup getsblocked whenever the soil water saturates the pores in the ceramic. As the soil dries,its moisture drops below a critical tension value, and the porous cup becomespermeable to air passage. In dry soils when the barrel is immersed into the water, themeniscus (air-water boundary) rapidly moves upwards in the barrel to equalize it to thewater level in the container. Whenever water enters the barrel, the soil is at least as dryas the calibration of the porous ceramic cup. The soil moisture is evaluated once a dayto determine the moment to irrigate. In sandy soils the evaluation is made twice a day.

The Irrigas had a nominal calibration of -25 kPa and when we subjected Irrigas toprogressive amounts of suction, the porous ceramic freely bubbled air at -25 kPa.Irrigas readings were taken every day at 9:00 AM.

The onion crop was irrigated at -25 kPa throughout the season based on average GMSreadings (Shock et al. 1 998b). With the establishment of this experiment in an onionfield, the onions in the entire sensor calibration trial were irrigated when the average

224

GMS reading reached -25 kPa on July 17 and 22. Since the Irrigas had not providedpositive readings, the next five irrigations were delayed until at least half of the eightIrrigas sensors indicated the need for irrigation.

The onions were lifted on September 8 to field cure. Onions from the middle two rowsin each replicate were topped by hand and bagged on September 15. Onions weregraded on September 16. During grading, bulbs were separated according to quality:bulbs without blemishes (No. Is), split bulbs (No. 2s), neck rot (bulbs infected with thefungus Botrytis al/il in the neck or side), plate rot (bulbs infected with the fungusFusarium oxysporum), and black mold (bulbs infected with the fungus Aspergillusniger). The No. 1 bulbs were graded according to diameter: small (<2.25 inches),medium (2.25-3 inches), jumbo (3-4 inches), colossal (4-4.25 inches), andsupercolossal (>4.25 inches). Bulb counts per 50 lb of supercolossal onions weredetermined for each plot of every variety by weighing and counting all supercolossalbulbs during grading.


All the sensors used in this study had advantages of low unit cost and simpleinstallation procedures. Both tensiometers and GMS demonstrated similarresponsiveness to wetting and drying of the soil (Fig. 1). In this trial, there were twoepisodes of irrigation based on GMS readings at —25 kPa and five irrigation eventsbased on the Irrigas criterion (Fig. 1). It took the same amount of time (4 hours) for allthe tensiometers and all GMS to indicate that the soil at 8-inch had reached saturationafter the onset of each irrigation episode. The relative similarity in responsivenessbetween tensiometers with pressure transducers and granular matrix sensors (GMS)was statistically confirmed by regression with a coefficient of determination of 0.92 (Fig.2). The Irrigas indicated free air permeability close to -35 kPa for Owyhee silt loam inthis trial (Fig. 1).

Large changes in tensiometer readings from -10 to -40 kPa translated into smallchanges in water content readings for the ECH2O dielectric aquameter (Fig. 3). Theexact responsiveness of the ECH2O dielectric aquameter to the soil water content wasbeyond the scope of this work. A comparison of the ECH2O dielectric aquameterreadings with soil volumetric water content from this field indicated that the readingswere relatively flat and nonlinear in response to changes in volumetric soil watercontent (Fig. 4). The relatively small changes in volumetric soil water content as readby the ECH2O dielectric aquameter occurred across the critical range of SWP for onionirrigation decisions.

The ECH2O dielectric aquameter was relatively easy to automate. The ECH2Odielectric aquameter was used in only one experiment and the readings were relativelyunresponsive to changes in soil water potential in the range of -10 to -40 kPa (Fig. 3)and relatively unresponsive to changes in volumetric soil water content in the range of23 to 38 percent (Fig. 4). The need for site specific calibrations noted here for theECH2O dielectric aquameter is consistent with the work of Evett et at. (2002), who

225

tested a variety of capacitance probes in widely divergent soils and recommended sitespecific calibrations.

The tensiometers with pressure transducers were easily automated. The tensiometersrequired servicing twice during the 76 days of the trial. More frequent servicing toreplace lost water should be expected when soils are not maintained as wet as in thepresent experiment. The GMS have limitations in reading SWP in soils wetter than —10kPa (Fig. 2), as has been described previously (Shock et al. 1998a), and in respondingin coarse texture soils (Shock 2003).

The model of Irrigas was only tested in one comparison experiment, where it appearedto be promising for irrigation scheduling at —35 kPa in silt loam, not the nominalspecifications of —25 kPa. Kemper and Amemiya (1958) pointed out that soil particleswhich surround and are in contact with a porous ceramic could cut down on airpermeability to some extent. From the limited experience of this trial, the interferenceof the soil with air permeability of porous ceramics is a possibility for further study. Wewould expect greater interference in fine textured soils at relatively high (wetter) SWPand less interference with coarse textured soils and at relatively low (drier) SWP.

Scheduling furrow irrigations at a criterion near -27 kPa has been shown to optimizelong-day onion yield and grade (Shock et al. 1998b). However, perhaps the Irrigasirrigation threshold of -35 kPa for August through the end of growing season may nothave been detrimental and may bring about a convenient reduction in irrigationfrequencies. An Irrigas type instrument could probably be manufactured with porositydesigned specifically for measurements at -25 kPa in silt loam.

The irrigation scheduling used in this field trial appeared to be adequate, since therewas an average onion marketable yield of 993 cwtlacre. Average marketable onionyield for 2000 through 2002 from commercial production in the Treasure Valley was 633cwt/acre.

Acknowledgments

We would like to thank Adonai Gimenez Calbo from CNPH-EMBRAPA, Brasilia, OF,Brazil, and Enison Pozzani from E-Design, Jundiai, SP, Brazil, for providing 8 -25 kPaIrrigas for testing. We would also like to thank Conselho de Desenvolvimento Cientificoe Tecnologico (CNPq) of Brazil for providing the Post-Doctoral scholarship and supportfrom Oregon State University that enabled this work.

References

Calbo, A.G. 2004. Gas irrigation control system based on soil moisture determinationthrough porous capsules. United States Patent, 6705542 B2.

226

Calbo, A.G., and W.L.C. Silva. 2001. Irrigas — novo sistema para controle da irrigacao.Pages 177-1 82 in Anais do Xl Congresso Brasileiro de Irrigacao e Drenagem.Fortaleza, CE.

Evett, S.R., J.P. Laurent, P. Cepuder, and C. Hignett. 2002. Neutron scattering,capacitance, and TDR soil water content measurements compared on four continents.Pages 1021-1-1021-10 in Transactions 17th World Congress of Soil Science, August14-21, 2002, Bangkok, Thailand (CD-ROM).

Kemper, W.D., and M. Amemiya. 1958. Utilization of air permeability of porousceramics as a measure of hydraulic stress in soils. Soil Science 85:117-124.

Shock, C.C. 2003. Soil water potential measurement by granular matrix sensors. Pages899-903 In B.A. Stewart and T.A. Howell (eds.). The Encyclopedia of Water Science.Marcel Dekker.

Shock, C.C., J.M. Barnum, and M. Seddigh. 1998a. Calibration of Watermark soilmoisture sensors for irrigation management. Pages 139-146 in Proceedings of theInternational Irrigation Show, Irrigation Association, San Diego, CA.


227

0

0

0

— Tensiometer - GMS

-10

-20

-30

-40

-50200 210 220 230 240 250 260 270

Day of the year

Figure 1. Soil water potential over time for tensiometers with pressure transducers andgranular matrix sensors in a furrow-irrigated onion trial. Arrows denote furrow irrigationswith 75 mm of water applied. The last five irrigations started based on Irrigas. MalheurExperiment Station, Oregon State University, Ontario, OR 2004.

Y=2.090+ 1.622X+O.01605X2R20.924 P0.0001 n=1852

0a-

-30

0 0

Tensiometer soil water potential, kPa

Figure 2. Soil water potential measured in a furrow-irrigated onion trial by a tensiometerwith transducers (X axis) regressed against soil moisture suction measured by agranular matrix sensor (Y axis). Data points are the average of eight instruments.Malheur Experiment Station, Oregon State University, Ontario, OR 2004.

228

-

050 40 30 20 10 0

Tensiometer soil water potential, kPa

Figure 3. Soil water potential measured in a furrow-irrigated onion trial by a tensiometerwith transducers (X axis) regressed against volumetric soil water content measured byan ECH2O dielectric aquameter (Y axis). Data points for soil water potential are theaverage of eight tensiometers. Data points for the ECH2O dielectric aquameter are theaverage of four sensors. Maiheur Experiment Station, Oregon State University, Ontario,OR 2004.

C)

______________________________________________

400

20 -

15

10 - V 33.16(1 - EXP(-0.1005(X -. 06930)))-$ 0.970 P = 0.01 n = 24

0 5 10 15 20 25 30 35 40

Dielectric volumetric water content, %

Figure 4. Regression of the volumetric soil water content measured by an ECH2Odielectric aquameter (X axis) against the classical gravimetric method (Y axis). Datapoints from each of four ECH2O dielectric aquameters were compared with two soilsamples in each of three soil moisture ranges. Malheur Experiment Station, OregonState University, Ontario, OR 2004.

229

FACTORS INFLUENCING VAPAM® EFFICACY ON YELLOW NUTSEDGE TUBERS



Introduction

Yellow nutsedge is a perennial weed common in irrigated row crop production in theTreasure Valley of Eastern Oregon and Southwestern Idaho. It is particularlyproblematic in onion production. Onion plants are relatively short in stature with verticalleaves producing an incomplete canopy with limited potential to effectively suppressweeds. The conditions of high light intensity as well as frequent irrigation and highnitrogen fertilization required to maximize onion yield also serve to stimulate yellownutsedge growth (Keeling et at. 1990). We have demonstrated that without anycompetition a single yellow nutsedge plant can produce over 18,000 tubers in a singleyear (Rice et al. 2004). We have also found that heavily infested commercial fields canhave as high as 1,800 tubers/ft2 in the top 10 inches of soil (unpublished data).Producers often apply Vapam® (metham sodium) in the fall prior to planting onions in anattempt to control yellow nutsedge. Control with Vapam is often variable and seems todepend on a number of environmental factors. The objective of this research was todetermine the effect of metham rate, duration of exposure, temperature of exposure,and yellow nutsedge tuber condition on metham sodium efficacy.


Trials were conducted at the Malheur Experiment Station in the laboratory to determinethe influence of metham sodium rate, duration of exposure, temperature duringexposure, and tuber conditioning on yellow nutsedge control. Yellow nutsedge tuberswere extracted from the soil in November and either stored at a constant 50°F in a smallvolume of soil or washed and subjected to 38°F for 4 weeks prior to the initiation of theexperiment. The conditioning treatment was meant to reduce tuber dormancy.Washing and chilling have been reported as effectively overcoming dormancy(Tumbleson and Kommedahl 1961). All tubers were produced from a single plant theprevious summer. Soil (1.76 Ib) and 15 tubers were placed in 1-quart jars. The soil wasan Owyhee silt loam. The soil was wetted to 14 percent moisture on a weight for weightbasis by adding one third of the water to the bottom of the jar, adding half the volume ofsoil and then the yellow nutsedge tubers, adding another third of water, adding theremaining soil and then the final third of the water. The jars were placed in growthchambers at 41, 55, or 77°F for 24 hr to equilibrate. Vapam was injected into the soil0.5 inch below the tubers at equivalent field rates of 0, 20, 40, 60, and 80 gal of productper acre based on soil volume. Jars were sealed and placed back in their respectivetemperatures for 1, 3, or 5 days. After each duration of exposure, the soil was removed

230

from the jars and the tubers were washed from the soil. Extracted tubers were placed inpetri-dishes between 2 pieces of filter paper and 5 ml of water was added to each dish.The petri-dishes were sealed and placed in the dark at 77°F. Germinated tubers wererecorded at the time of removal and weekly for 6 weeks. Treatments were replicatedfour times and the trial was repeated once after the initial run. Total percent tubergermination was analyzed by ANOVA. For each combination of exposure temperature,exposure duration, and tuber conditioning, tuber sprouting response to Vapam dosewas fitted to the logistic model:

D —C1 + (x / 150 )b

Where y = the percent sprouting yellow nutsedge tubers, x = metham sodium rate, C =percent tubers sprouting at high rates, D = percent of tubers sprouting in the non-treatedtreatment, b = the slope at the /50 dose, and = the dose providing 50 percentreduction in sprouting tubers (Seefelt et al. 1995).


In general, tuber sprouting was affected by metham sodium rate, temperature ofexposure, duration of exposure, and yellow nutsedge tuber conditioning. This is inagreement with research by Boydston and Williams (2003), which evaluated fumigantaffects on volunteer potatoes. All main effects and interactions were significant (Table1). The /5Q dose for metham sodium under various conditions ranged from 21.64 to>80.0 gal/acre and was lower for conditioned tubers compared to nonconditioned tubersacross all conditions except for tubers exposed at 77°F for 3 or 5 days (Table 2). Non-conditioned tubers had lower germination in preliminary trials (data not shown), butwashing and other conditions during the trial overcame any dormancy as D values(maximum germination) were similar among all treatments. Nonconditioned tubers didrequire more time to germinate than conditioned tubers (data not shown).Nonconditioned tubers were unaffected by metham sodium rate at I day exposure at41°F (Fig. 1). For nonconditioned tubers, increasing exposure temperature, andincreasing duration of exposure decreased sprouting. As duration of exposure ortemperature of exposure increased, differences among conditioned and nonconditionedtUbers decreased. Metham Sodium must be converted to methyl isothiocyanate (MITC)to have activity against yellow nutsedge. At lower temperatures conversion of methamsodium to MITC takes place at a slower rate. In addition to slow conversion of methamto MITC, the reduced response of yellow nutsedge tubers at cooler temperatures couldalso be attributed to yellow nutsedge tubers being less metabolically active. The similarresponse of conditioned tubers regardless of duration of exposure at 59 or 77°F and theincreased response of nonconditioned tubers to increasing duration of exposure,suggests that at 59 and 77°F metham sodium conversion to MITC is not the limitingfactor, but rather uptake by the nonconditioned nutsedge tubers may have been thelimiting factor. In contrast, at 41°F, both conditioned and nonconditioned tubersresponded to increasing duration of exposure, suggesting that both rate of metham

231

sodium conversion to MITC and uptake by the tubers were having an affect on methamsodium efficacy. /50 values were actually lower for conditioned tubers exposed for 5days at 41°F compared to 59 or 77°F. This result is difficult to explain. It may be thatwhile conversion of metham sodium to MITC is faster at high temperatures, breakdownof MITC is also increased. This research illustrates that fumigant efficacy depends onthe dose reaching the target organism. While the rate applied directly influences thedose, environmental or physiological factors may affect what dose the yellow nutsedgereceives. Applying metham sodium at a time when yellow nutsedge tubers are moresusceptible may increase metham sodium efficacy against yellow nutsedge.

References

Boydston, R. A., and M. M. Williams II. 2003. Effect of soil fumigation on volunteerpotato (Solanum tuberosum) tuber viability. Weed Technol. 17:352-357.

Keeling, J. W., 0. A. Bender, and J. R. Abernathy. 1990. Yellow nutsedge managementin transplanted onions. Weed Technol. 4:68-70.

Rice, C. A., C. V. Ransom, and J. K. Ishida. 2004. Yellow nutsedge (Cyperusesculentus) response to irrigation and nitrogen fertilization. Proc. West. Soc. Weed Sd.57:42-43, No.65.

Seefelt, S. S., J. E. Jensen, and E. P. Fuerst. 1995. Log-logistic analysis of herbicidedose-response relationships. Weed Technol. 9:218-225.

Tumbleson, M. E., and 1. Kommedahl. 1961. Reproductive potential of Cyperusesculentus by tubers. Weeds 9:646-653.

Acknowledgement

Thanks to the Idaho/Eastern Oregon Onion Growers Association for financial support.

232

Table 1. Significance of ANOVA main effects and interactions for total percent of yellownutsedge tubers sprouting.Factor PDose 0.00001Temperature 0.00001Time 0.00001Conditioning 0.00001Dose by temperature 0.00001Dose by time 0.00001Temperature by time 0.00001Conditioning by dose 0.00001Conditioning by temperature 0.00001Conditioning by time 0.00001Dose by temperature by time 0.00001Dose by temperature by conditioning 0.00001Temperature by time by conditioning 0.00001Dose by time by conditioning 0.00001Dose by temperature by time by 0.00001conditioning

233

Figure 1. Yellow nutsedge germination in response to rate, temperature ofexposure, duration of exposure, and conditioning of the yellow nutsedge tubers.Conditioned tubers were washed and chilled at 38°F for 4 weeks prior to trial initiation.Nonconditioned tubers were stored in soil at a constant 50°F. Malheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

234

1 day exposure 3 day exposure 5 day exposure• Non-conditioned

Conditioned

• Non-conditionedo CondItioned

100

80

6041 F

40

20

0

100

180.059 FC) 40

C)>-

100

80

60

77 F40

20

0•

0 20 40 60 80 0 20 40 60 80 0 20 40 60 80

Equivatent Vapam rate (gal/acre)

Table 2. Estimated parameters for nonlinear regression analysis of yellow nutsedge sprouting in response to Vapam®

rate, exposure temperature, exposure duration, and yellow nutsedge tuber conditioning. Standard errors are inDarentheses.*. Maiheur Experiment Station, Oregon State University, Ontario, OR, 2004.Temperature' Time Tuber condition D

IC 150 b R2

°F days % —--- gal/acre41 1 Nonconditioned -- -- -- -- 0.00

Conditioned 93.16 (6.23) 0.00 (56.29) 49.57 (36.77) 1.82 (1.15) 0.653 Nonconditioned 96.21 (3.21) 6.34 (26.29) 63.18 (7.10) 6.59 (3.73) 0.84


Conditioned 90.84 (2.84) 1.69 (2.04) 21.64 (4.61) 10.00 (26.72) 0.9659 1 Nonconditioned 98.20 (2.78) 0.00 (126.09) 75.24 (37.21) 5.57 (4.91) 0.80



Conditioned 99.01 (1.04) 0.00 (0.75) 27.48 (0.93) 10.00 (0.99) 1.0077 1 Nonconditioned 95.86 (1.64)

—

0.00 (2.65) 38.62 (0.63) 6.72 (1.76) 0.98Conditioned 94.99 (2.95)

—

0.00 (2.31) 25.37 (1.31)_ 6.02 (1.06) 0.963 Nonconditioned 95.60 (2.86) 0.00 (2.22) 26.24 (1.31)_ 6.21 (0.94) 0.97


Conditioned 94.16 (1.78) 0.00 (1.29) 28.64 (1.48) 9.20 (1.35) 0.99*Abbreviations: D, percent of tubers sprouting in nontreated treatment; C, percent of tubers germinating at high methamdose; 15Q, dose causing a 50 percent reduction in sprouting tubers; b, slope at '50 dose. For one treatment the /50 washigher than the rates evaluated.

YELLOW NUTSEDGE GROWTH IN RESPONSE TO ENVIRONMENT

Corey V. Ransom, Charles A. Rice, Joey K. Ishida, and Clinton C. ShockMalheur Experiment Station


Introduction

Yellow nutsedge is a perennial weed common in irrigated row crop production in theTreasure Valley of eastern Oregon and southwestern Idaho. It is particularlyproblematic in onion production. Onions are relatively short statured plants with verticalleaves producing an incomplete canopy with limited potential to effectively suppressweeds. Yellow nutsedge has a C4 photosynthetic pathway and therefore responds wellto conditions of high light intensity that exist in onion production. Managementpractices including frequent irrigation and high nitrogen fertilization required to maximizeonion yield also serve to stimulate yellow nutsedge growth (Keeling et al. 1990).

Yellow nutsedge reproduces and is dispersed primarily by tubers' that are formed at theapical ends of underground rhizomes. Tubers are produced in the upper 18 inches ofthe soil profile with the greatest concentration located in the upper 6 inches (Stoller andSweet 1987, Tumbleson and Kommedahl 1961). After a period of dormancy, tubersgerminate and produce shoots in subsequent growing seasons. Tubers may remainviable for 1-3 years, providing an effective means of survival. Asexual reproduction byyellow nutsedge tubers can be quite prolific. Tumbleson and Kommedahl (1961)reported that a single tuber produced 6,900 tubers the first fall after planting and 1,900plants the following spring in an area of approximately 34ft2. Yellow nutsedge growsbest where soil moisture is high (Bendixin and Nandihalli 1987). Garg et al. (1967)reported that nitrogen promotes vegetative growth over reproductive growth in yellownutsedge, leading to increased basal bulb formation (and subsequent shoot production)as opposed to tuber formation.

Two trials were conducted in 2004 at the Malheur Experiment Station to evaluate yellownutsedge growth with various environmental factors.

Methods

Yellow nutsedge emergence and growth as influenced by depth of germinationThe objectives of this experiment were to 1) determine the depth from which a yellownutsedge tuber can emerge in the field, 2) determine the date of emergence based ondepth of burial, and 3) determine the growth (i.e., shoot and tuber production) potentialbased on burial depth.

236

Yellow nutsedge tubers were harvested from a plot from the previous year's irrigationtrial on April 16, 2004. The tubers were washed from the soil, rinsed with deionizedwater, and placed in a refrigerator at 38.5°F for approximately 14 days. Both washingand chilling have been shown to effectively break tuber dormancy (Tumbleson andKommedahl 1961, Bell et al. 1962). This was necessary to ensure that the tuberswould readily germinate when buried and that any differences in emergence would bebased on depth of burial and/or soil temperature and not differences in dormancy. Tentubers were buried in a single container at a selected depth of either 2, 4, 6, 8, 10, 12,14, 16, 18, or 24 inches on May 1. Each depth was replicated four times. Containersconsisted of 10-inch-diameter pvc pipe. Temperature sensors were placed at 6, 12, 18,and 24 inches deep in 1 tube in each replication. Each container was irrigated by asingle drip emitter with an output of 0.5 gal/hr. Watermark sensors (Irrometer Co. Inc.,Riverside, CA) were buried 6 inches deep in every pot in the first and third replicate ofthe trial. Soil water potential was measured every morning. Irrigations were initiatedeach time the average of the Watermark sensors was greater than or equal to -20 kPa.Shoots were counted throughout the season and shoots and tubers were harvested onJuly 7.

Yellow nutsedge growth in response to irrigation and nitrogen fertilizationThe objectives of this experiment were to 1) monitor patch expansion from a singleyellow nutsedge tuber in the absence of crop competition over the course of onegrowing season, 2) evaluate the effects of selected irrigation regimes on yellownutsedge growth, and 3) evaluate the effect of nitrogen fertilization on yellow nutsedgegrowth.

Tubers for this trial were harvested from a ditch bank, were washed from the soil, rinsedwith deionized water, and stored in a refrigerator at 38.5°F for approximately 40 days.Tubers weighing from 0.18 to 0.2 g and measuring between 6 and 7 mm were selectedand planted in flats in the greenhouse. Tubers of similar size and weight were selectedbecause research has shown that tuber size can affect early plant vigor, with plantsfrom smaller tubers being less vigorous. On June 4, a single germinated tuber with ashoot of at least 1 inch long was transplanted into the center of each circular plot of 6-ftdiameter. Transplanted yellow nutsedge plants were used to ensure a more uniformdate of establishment among the 18 individual plots. The circular plots consisted of 14-inch-wide galvanized valley flashing cut to a length of 19 ft with the ends rivetedtogether to produce a circle with a diameter of 6 ft. The flashing was then buriedapproximately 10 inches deep in the soil. Prior to transplanting, each plot was dripirrigated to a soil moisture potential of -20 kPa to incorporate fertilizer applications andto provide similar moisture conditions for early yellow nutsedge establishment.

The trial consisted of 18 circular plots, 6 each for the 3 irrigation regimes and 3 each forthe 2 fertilization levels split over the irrigation regimes. Irrigation water was applied tothe plots through 6 drip emitters evenly spaced in a circular pattern, where each emitterwas located 1.5 ft from the center of the plot. The 6 emitters had a combined output of3.0 gal/hr. The values for irrigation criteria were -20, -50, and -80 kPa and wereselected to represent soil moisture conditions similar to those in wheat, sugar beet, and

237

dry bulb onion production systems, respectively. The 2 fertilization levels consisted ofplots receiving nitrogen (N) (46 percent urea) at rates of either 90 or 268 lbs N/acre. Allplots were fertilized before transplanting with 90 lbs phophorus/acre, 90 lbs sulfur/acre,1 lb copper/acre, 1 lbs boron/acre, and 9 lbs magnesium/acre. Soil water potential wasmeasured in each plot with a single Watermark soil moisture sensor installed at a 6-inch depth equidistant from the yellow nutsedge plant at the center of the plot and thedrip line, Irrigation water was applied independently for each regime when the average6-inch soil water potential from the 6 sensors reached either -20, -50, or -80 kPa. Thesensors were read by a datalogger every 3 hours, and once every 12 hours irrigationwas initiated using a solenoid valve if the soil water potential had exceeded thetreatment criteria during the previous 12-hour period. Water meters were installedbetween the solenoid valves and the water line for each individual irrigation regime torecord the amount of water applied daily.

Yellow nutsedge growth was measured initially by counting shoot numbers within eachplot and by taking overhead digital images of each plot. At a point where shootsbecame too numerous to efficiently count, only overhead digital images were taken ofeach plot. These images were used to quantify the plot area that was covered byyellow nutsedge shoots using a software program produced at Oregon State University(OSU). Shoots and tubers were harvested from subsamples within each plot onSeptember 29 and 30. Thirteen subsamples were collected across the 6-ft diameter ofthe plots. The subsamples consisted of 4.25-inch-diameter circles from which shootswere counted to estimate the total shoot number per plot. The shoots were thenclipped at ground level and placed in bags to be dried. The dry weights were used toestimate the total above-ground biomass. Once the shoots were removed, a soil coremeasuring 4.25 inches in diameter by 8 inches in depth was taken from the same areawhere the shoots were removed. The individual core samples were bagged andrecorded as to their location within the plot. The core samples were then emptied into abucket with multiple 11/64-inch holes in the bottom and sides. Water was sprayed intothe bucket to remove the soil from the tubers. The tubers were then counted andweighed and those numbers were used to estimate the total tuber population for eachof the plots.


Yellow nutsedge emergence and growth as influenced by depth of germinationPlots where tubers were planted from 2 to 12 inches deep had an average of 1-5shoots emerged on May 24, while deeper depths had no shoots for another week ormore (data not shown). The time required for treatments to produce an average 5shoots per plot ranged from 24 to 68 days after planting. The time required for 10shoots per plot to emerge ranged from 34 to 55 days for burial depths up to 18 inches.The tubers buried at the 24-inch depth produced a maximum of 6 shoots at the time theplots were harvested. The average daily soil temperatures at 6, 12, 18, and 24 inchesfrom planting through harvest are illustrated in Figure 1 and show that temperatureextremes are greatest nearer the soil surface, If tubers were buried earlier in the year,we might expect to see greater differences among emergence dates based on

238

differences in the time required for the soil at each depth to reach temperaturesfavorable for yellow nutsedge germination. Figure 2 shows the emergence of shoots asaffected by planting depth from May 24 through June 7. At harvest, shoot numberswere similar in plots where tubers were planted from 2 to 16 inches deep (Table 1).Tubers planted 18 and 24 inches deep had fewer shoots than all other planting depthsand the 24-inch depth had the least number of shoots. The average weight per shootwas less for 16-, 18-, or 24-inch depths compared to depths from 2 to 12 inches (datanot shown). Tuber numbers were lower for plots where the planting depth was 14inches or greater, with significant decreases as depth increased from 12 to 24 inches.

This research demonstrates that yellow nutsedge shoot emergence is delayed atdepths below 12 inches. Those shoots that emerge are fewer in number and at depthsbelow 16 inches are also smaller in size. This delay in emergence affects how manytubers can be produced, and it is reasonable to expect that the delay in emergence andreduction in individual shoot fitness would correlate with reduced competitiveness fromyellow nutsedge emerging from depths greater than 14 inches in the soil.

Table 1. Yellow nutsedge shoot emergenceinfluenced by depth of germination, MalheurUniversity, Ontario, OR, 2004.

andExpe

shoot and tuber production asriment Station, Oregon State

Time to emergence Yellow nutsedge production*Average> 5 Average 10

Depth of burial Shoots Tubersdays after planting

2-inch 35 41

no/plot91 b 250 b

4-inch 25 39 ll5ab 334a

6-inch 24 34 101 ab 333 a

8-inch 27 39 126a 313ab

10-inch 27 39 lO8ab 240b

12-inch 31 39 119a 272ab

14-inch 39 40 119a 167c

16-inch 39 45 lO8ab 97cd

18-inch 45 55 66c 3Ode

24-inch 68 >68 6d lOe*Yellow nutsedge tubers were buried at the various depths on May 1 2004, and yellow nutsedge shoots and tubers were harvestedon July 7, 2004. Data followed by the same letter are not signficicant according to LSD (0.05).tDays after planting for which the average of the 4 replicates for the given depth of burial were greater than or equal to 5.tDays after planting for which the average of the 4 replicates for the given depth of burial were greater than or equal to 10.

239

LL

G)I-

0)a-E0)4-I

0C/)

4-I0a-0C

0)C.)

C0)a)L.0)

E0)0)

.D0)

C

00)

0)C,

0)>

80

75

70

65

60

55

50

4/26/2004 5/10/2004 5/24/2004

-J6"

— 18"— —. 24"

6/7/2004 6/21/2004 7/512004

Date

Figure 1. Average daily soil temperature at 6-, 12-, 1 8-, and 24- inch depths fromyellow nutsedge tuber planting up to shoot and tuber harvest, Malheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

0 2-in• 6-in

———v--—— 8-in10-in— — 12-in

— —0—. — 14-in16-in18-in

0 24-in

140

120

100

80

60 -

40

20

0

'7'

/

5/23/05 5/30105 6/6/05

-00--

6/13/05 6/20/05 6/27/05 7/4/0 5

Date

Figure 2. Yellow nutsedge shoot emergence over time as influenced by depth ofgermination, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

240

Yellow nutsedge growth in response to irrigation and nitrogen fertilizationThere were no significant interactions between irrigation criteria and fertilization.Nitrogen fertilization did cause a significant increase in shoot number, but not on shootbiomass, tuber number, total tuber weight per plot, or individual shoot or tuber weight(data not shown). Since there were no interactions, irrigation criteria data wereaveraged over fertilization levels. Irrigation events and total water applied are shown inTable 2. The number of irrigations and the total amount of water applied were muchless for the -20-kPa and —50-kPa irrigation treatments compared to 2003. This mayhave been because temperatures were lower in 2004 compared to 2003. Soil moisturepotential over time by irrigation regime is illustrated in Figure 3. Irrigation had asignificant effect on yellow nutsedge shoot number and total weight (Table 3). The —20-kPa irrigation treatment produced an average of 1,747 shoots per plot. This wassignificantly greater than the —50-kPa and —80-kPa irrigation treatments, whichproduced 444 and 411 shoots per plot, respectively. All shoot numbers were muchlower than in 2003. The —50-kPa and —80-kPa treatments produced similar numbers ofshoots, while in 2003 the —50-kPa treatment produced almost twice as many shoots asthe —80-kpa treatment. The —20-kPa irrigation treatment produced an average of 2.7 lbof shoot biomass per plot and the shoots in this treatment had higher weight per shootthan in the other irrigation treatments. Based on the digital images, the area infested bythe yellow nutsedge shoots grew quickest for the —20-kPa treatment and much slowerwith either the —50- or —80-kPa treatments (Fig. 4). Similar to 2003, the amount of areainfested was fairly small from June 4 to July 19. Over a 27-day period from July21 toAugust 17 the area infested by yellow nutsedge in the —20-kPa treatments increasedfrom 2.6 to 22.6 ft2. Yellow nutsedge tuber production was higher with the —20-kPairrigation criterion compared to the other irrigation criteria and total numbers for thistreatment were similar to 2003 (Table 4). An average of 19,508 tubers/plot wereproduced from a single plant with the —20-kPa treatment. The —50- and —80-kPatreatments produced 4,447 and 5,826 tuber, respectively. The —50-kPa treatmentproduced 10,000 fewer tubers in 2004 than in 2003.

This year's results demonstrate that under high levels of irrigation yellow nutsedge canproduce large numbers of shoots and tubers. This continues to be much higher thanpreviously reported in the literature. However, the differences between 2003 and 2004suggest that factors other than irrigation criteria may significantly affect the productivepotential of yellow nutsedge when irrigation levels are moderate.

241

Ct

0

Ct

0Cl)

Table 2. Number of irrigations, amount applied per irrigation,Maiheur Experiment Station, Oregon State University, Ontario,

and total water applied,OR, 2004.

Irrigation criteria Irrigations Total applied*

kPa number/plot-20 45

inches/event0.32

inches/plot15.9

-50 7 1.0 8.5

-80 4 1.38 7.0

*Total includes 1 .48 inch of rainfall.

0

-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

Date

Figure 3. Soil moisture potential over time by irrigation regime, Malheur ExperimentStation, Oregon State University, Ontario, OR, 2004.

242

6/11 6/21 6/30 7/10 7/20 7/29 8/8 8/18 8/27 9/6 9/15

Table 3. Yellow nutsedge shoot production as influenced by irrigation, MaiheurExperiment Station, Orecion State University, Ontario, OR, 2004.

Irrigation Yellow nutsedge shoots*

kPa

-20

no./plot1,747a

no/ft262a

lb/plot2.7a

lb/ft2

0.095ag/shoot0.71a

-50 444 b 16 b 0.5 b 0.019 b 0.51 b

-80 411 b 15b 0.5b 0.018b 0.56b

*Values followed by the same letter de signation are not s tatistically different (P 0.05).

• -2OkPa-5OkPa

N

C)4-I(0

C

(0C)

5000

4000

3000

2000

1000

0

6/1104

——---V

——----y--—--—v

7/1/04 8/1/04

Date

9/1/04 10/1/04

Figure 4. Yellow nutsedge patch expansion over time based on percent groundcoverage between transplanting and harvest, Malheur Experiment Station, OregonState University, Ontario, OR, 2004.

243

Table 4. Yellow nutsedge tuber production as influenced by irrigation, MaiheurExperiment Station, Oreaon State University, Ontario, OR, 2004.

Irrigation Yellow nutsedge tubers

kPa no/plot no/ft2 lb/plot lb/ft2 g/tuber-20 19,508 a 690 a 5.1 a 0.18 a 0.12 b

-50 4,447b 157b 1.5b 0.005b 0.15 a

-80 5,826b 207b 1.7b 0.006b 0.13b

*Values followed by the same letter designation are not statistically different (P = 0.05).

References

Bell, R. S., W. H. Lachman, E. M. Rahn, and R. D. Sweet. 1962. Life history studies asrelated to weed control in the northeast. 1. Nutgrass. Rhode Island Agric. Exp. Stn. Bull.364. 33 pages.

Bendixen, L. E., and U. B. Nandihalli. 1987. Worldwide distribution of purple and yellownutsedge (Cyperus rotundus and C. esculentus). Weed Technol. 1:61-65.

Garg, D. K., L. E. Bendixen, and S. R. Anderson. 1967. Rhizome differentiation inyellow nutsedge. Weed Sci. 15:124-128.

Keeling, J. W., D. A. Bender, and J. R. Abernathy. 1990. Yellow nutsedge (Cyperusesculentus) management in transplanted onions (A ilium cepa). Weed Technol. 4:68-70.

Tumbleson, M. E., and T. Kommedahl. 1961. Reproductive potential of Cyperusesculentus by tubers. Weeds 9:646-653.

Stoller, E. W., and R. D. Sweet. 1987. Biology and life cycle of purple and yellownutsedges (Cyperus rotundus and C. esculentus). Weed Technol. 1:66-73.

244

YELLOW NUTSEDGE CONTROL IN CORN AND DRY BEAN CROPS



Introduction

Yellow nutsedge is an increasing weed problem in the Treasure Valley of easternOregon and southwestern Idaho. Yellow nutsedge is particularly detrimental in onionproduction due to the noncompetitive nature of the crop and the ability of yellownutsedge to proliferate under the growing conditions that exist in onion production.Previous research conducted in the Treasure Valley evaluating yellow nutsedge controlin onion has met with limited success, in part due to the lack of effective herbicideoptions and the weed's ability to germinate over long periods of time during the growingseason. An integrated approach is needed to manage yellow nutsedge, including theuse of effective herbicide treatments in each of the crops within a rotation. In 2003,several herbicide treatments in corn and dry bean significantly reduced the number ofyellow nutsedge tubers in the soil. This research was conducted to further evaluate theeffects of crop species and herbicides on growth and development of yellow nutsedgein field corn and dry bean production.

Methods

Studies were conducted in a field heavily infested with yellow nutsedge located north ofOntario on the Oregon Slope. The soil was a Owyhee silt loam with pH 8.5 and 1.7percent organic matter. The field was disked on May 19 and ground hogged on May20. The field was bedded for corn and dry bean on May 21 and preirrigated. Plotswere 7.33 ft wide and 30 ft long and were replicated 4 times and arranged in arandomized block design. Pretreatment nutsedge tubers were sampled May 31, whichconsisted of taking 8 core samples measuring 4.25 inches in diameter and 7 inchesdeep from the center furrow within each individual plot. The samples were combinedand the tubers were extracted from the soil by washing the soil through screens with11/64-inch holes. To determine treatment effects on tuber numbers, core sampleswere taken again at harvest. Season-end core samples were taken from the bed topsof the center two rows in each plot. Four cores were sampled from each row. Theextraction process for season-end yellow nutsedge tubers was the same as for theinitial samples. In total, tuber sampling involved taking 1,280 core samples andwashing tubers from approximately 3.9 tons of soil. Herbicide applications were madewith a CO2-pressurized backpack sprayer calibrated to deliver 20 gal/acre at 30 psi.Crop injury and visual evaluations of yellow nutsedge control were made throughout thegrowing season. Yields were taken for each crop by harvesting the center two rows ofeach plot.

245

CornBeds were sidedressed with 150 lbs of nitrogen (N) on May 31. The field was harrowedon June 1 and preplant incorporated (PPI) Dual II Magnum® (s-metolachlor) treatmentswere applied to plots and incorporated by making two passes with the bed harrow inopposite directions. Pioneer 'P-36N69 Roundup Ready' field corn was planted on June1 on a 7-inch seed spacing on 22-inch rows. Mid-postemergence treatments wereapplied June 21 and late postemergence treatments were applied on June 29.

treatments included Basagran® (bentazon), Permit® (halosulfuron), andRoundupR (glyphosate). Basagran and Roundup were applied once following PPI DualMagnum, twice alone, or twice following PPI Dual Magnum. Permit was applied oncealone and in combination with Basagran following PPI Dual Magnum. Basagran andPermit were applied in combination with a crop oil concentrate (COC) while ammoniumsulfate (AMS) was added to Roundup applications. Yield was determined by harvestingears from the center two rows of each plot on October 12. The ears were shelled, andgrain moisture content and weights were recorded. Final yields were adjusted to 12percent moisture content.

Dry BeanOn May 31, plots were sidedressed with 150 lb N/acre. On June 1, beds wereharrowed, and PPI herbicide treatments were applied and incorporated by harrowingthe beds twice more in opposite directions. PPI treatments included Dual MagnumR (s-metolachlor), Eptam® (EPTC), and a combination of Dual Magnum plus Eptam. Smallwhite beans ('Aurora' variety) were planted and Prowl® (pendimethalin) was appliedpreemergence to help control weeds other than yellow nutsedge. On June 11, due topoor bean emergence, we decided to replant. The field was sprayed with 0.75 lbai/acre Roundup and 2.5 lb/acre of AMS to remove the beans that had emerged. Adifferent variety of pinto bean 'Othello' was planted on June 14. Postemergencetreatments were applied July 6 and included Sandea® (halosulfuron) plus nonionicsurfactant (NIS) and Basagran plus COC. The plots treated with Basagran received asecond application of Basagran on July 21. On September 16, plants were pulled fromthe center two rows of each plot to determine dry bean yield. After the bean plants haddried, the beans were threshed by with a Hege plot combine.


CornThe corn rotation had some of the best yellow nutsedge control and all treatments hadless tuber production compared to the untreated check (Table 1). Corn was not injuredby any of the herbicide treatments evaluated. Yellow nutsedge control ranged from 68to 97 percent on July 8 and 79 to 97 percent on July 28 (Table 1). Dual II Magnumalone and Roundup applied twice provided the least control on July 8 and Dual IIMagnum provided less control than all other treatments on July 28. Treatments withherbicides applied PPI and followed by multiple postemergence (POST) applicationstended to have greater yellow nutsedge control than treatments with only PPI or POSTtreatments. Tuber numbers increased by 55 percent in the untreated plots. In

246

herbicide-treated plots the change in yellow nutsedge tuber numbers ranged from a 68percent decrease to a 2 percent increase. Dual II Magnum followed by Permit plusCOC resulted in significantly fewer tubers than Dual II Magnum followed by oneapplication of Basagran plus COC. Corn yields did not differ significantly amongtreatments and ranged from 224 to 246 bu/acre.

Dry BeanDry beans also appear to have effective options for yellow nutsedge control. On theJuly 8 evaluation, yellow nutsedge control was significantly better with Eptam plus DualMagnum when both were applied PPI as compared to Eptam applied PPI and DualMagnum applied preemergence (PRE) (Table 2). On July 8, treatments with DualMagnum applied PPI were more effective than Eptam PPI followed by Dual MagnumPRE. At this rating, POST treatments had been applied only 2 days earlier and yellownutsedge was not exhibiting symptoms. On July 28, herbicide treatments provided 59-91 percent yellow nutsedge control. Treatments with only PPI or POST herbicides weregenerally less effective than combinations with a PPI application followed by one or twoPOST herbicide applications. Yellow nutsedge tuber numbers increased by 77 percentin the untreated plot. In the herbicide-treated plots, the change in yellow nutsedgetuber numbers ranged from a 43 percent decrease to a 7 percent increase with nosignificant differences between herbicide treatments. All herbicide treatmentsincreased dry bean yield compared to the untreated check. Basagran applied twicePOST had lower bean yield than Eptam plus Dual Magnum applied PPI.

247

Table 1. Corn yield, yellow nutsedge control, and yellow nutsedge tuber response toherbicide treatments, Malheur Experiment Station, Oregon State University, Ontario,OR, 2004.

Treatment3 Rate TimingbCropyield

Nutsedge control Average nutsedge tubers

7-8 7-28 Initial Final Change

Untreated control

lb ai/acre%v/v

-- --

bu/acre

224

/-- --

2no/ft

148 220

,,

55

Dual II Magnum 1.6 PPI 243 68 79 164 77 -32

Basagran + COCBasagran + COC

1.0 + 1.0%1.0 + 1.0%

MPLP

240 94 86 172 62 -57

Roundup + AMSRoundup + AMS

0.58 + 2.50.58 + 2.5

MPLP

235 69 88 193 75 -54

Dual II MagnumBasagran + COC

1.61.0 + 1.0%

PPILP

236 84 89 123 78 2

Dual II MagnumRoundup + AMS

1.60.58 + 2.5

PPIMP

246 79 87 154 72 -49

Dual II MagnumPermit + COC

1.60.031 + 1.0%

PPIMP

231 83 95 238 64 -68

Dual II MagnumBasagran +Permit + COC

1.61.0 +

0.031 + 1.0%

PPIMP

229 97 97 260 69 -67

Dual II MagnumRoundup + AMSRoundup + AMS

1.60.58 + 2.50.58 + 2.5

PPIMPLP

245 83 92 248 89 -53

Dual II MagnumBasagran + COCBasagran + COC

1.61.0 + 1.0%1.0 + 1.0%

PPIMPLP

242 96 97 199 73 -58

LSD (0.05) -- -- NS 10 6 NS 33 59

= crop oil concentrate, AMS = ammonium sulfate.bApplication timing abbreviations and dates: Preplant incorporated (PPI) on June 1 mid-postemergence (MP) on June 21, andlate postemergence (LP) on June 29.

248

Table 2. Dry bean yield, yellow nutsedge control, and yellow nutsedge tuber responseto herbicide treatments, Maiheur Experiment Station, Oregon State University, Ontario,OR, 2004.

Treatmenta Rate TimingbCropyield

Nutsedge control

7/8 7/28

Average nutsedge tubers

Initial Final Change

lb al/acre%v/v cwt/acre no/ft2

Untreated control 33 -- -- 236 365 77

Dual Magnum 1.6 PPI 41 76 59 198 149 3

EptamDual Magnum

3.91.6

PPIPRE

42 40 68 352 231 -14

EptamDual Magnum

3.91.3

PPIPPI

45 78 76 218 141 -28

Dual MagnumSandea + NIS

1.6.031+25%

PPIPOST 44 81 91 235 172 7

Dual MagnumSandea+Basagran + NIS

Basagran + COCBasagran + COC

Dual MagnumBasagran + COC

1.6.031+

1.0+25%

1.0+1.0%1.0+1.0%

1.61.0+1.0%

PPIPOSTPOST

POSTLP

PPIPOST

43

40

43

73 91

4 70

75 85

271 128 -43

255 177 -24

206 155 -12

Dual MagnumBasagran + COCBasagran + COC

1.61.0+1.0%1.0+1.0%

PPIPOST

LP42 75 90 279 158 -20

LSD (0.05) 4 20 10 156 75 65

aThe entire trial was treated with Prowl (1.0 lb al/acre) preemergence for control of weeds other than yellow nutsedge.ionic surfactant, COC = crop oil concentrate.bApplication timing abbreviations and dates: Preplant incorporated (PPI) on June 1 preemergence (PRE), postemergence (POST)on July 6, and late postemergence (LP) on July 21.

249

CHEMICAL FALLOW FOR YELLOW NUTSEDGE SUPRESSION FOLLOWINGWHEAT HARVEST



Introduction

Yellow nutsedge is extremely competitive with onions and other crops. Few herbicidetreatments are effective for managing yellow nutsedge within an onion crop. Herbicidesthat can be used in corn and dry bean can effectively reduce yellow nutsedge tubers inthe soil. Generally, we think that yellow nutsedge does not grow well in a wheat cropbecause wheat is so competitive. However, following wheat harvest, yellow nutsedgeshoots can be seen actively growing. Little is known about yellow nutsedge growthfollowing wheat harvest and its potential to produce additional tubers during this time.Also, the time between wheat harvest and fall ground preparation may be a window tofurther reduce the yellow nutsedge population. A special registration for Eptam® inArizona allows its use in the late summer as a fallow treatment in preparation for awinter crop. We conducted a trial to determine the number of tubers produced byyellow nutsedge following wheat harvest, and whether the use of Eptam as a chemicalfallow could reduce tuber production.

Methods

A wheat field with a prior history of severe yellow nutsedge infestation was selected forthis trial. Following wheat harvest, the field was corrugated and irrigated. As soon asthe field was dry enough it was disked to remove yellow nutsedge shoots that hademerged and to level the field. Once the surface was dry, Eptam was applied at 7.0pt/acre and immediately incorporated by disking to approximately 6-inch depth. Thetreatments compared in the trial included disking only or disking plus Eptam. The trialarea was left undisturbed until bedding in the fall. Eptam was applied with a CO2-pressurized backpack sprayer delivering 20 gal/acre at 30 psi. Plots measured 12 ftwide by 30 ft long and were replicated 4 times in a randomized complete block design.Shoot emergence was monitored by counting shoots within 1-yd2 quadrats. Changes intuber numbers were documented by taking 8 core samples 4.25 inches in diameter and7 inches deep from each plot and washing the tubers from the soil. Core samples weretaken prior to treatment and again at the conclusion of the trial. Initial core sampleswere taken August 3 and final core samples were taken October 21. In addition tosampling in the trial area, samples were taken from an area adjacent to the trial toprovide observational data on the effect of disking once, disking twice, and disking twicewith Eptam incorporated with the second disking.

250

Data were analyzed using paired t-tests at the 5 percent level (0.05).


The Eptam fallow label says that the field should not be irrigated for as long as possibleto prevent the Eptam from volatilizing from the soil. The day after the Eptam treatmentsat least 0.5 inches of rain fell across the valley. Eptam incorporated with diskingreduced yellow nutsedge shoot and tuber numbers compared to disking alone (Table1). In plots that were disked only, tuber numbers increased by 97 percent while in plotswhere Eptam was incorporated with the disking, tuber numbers only increased 7percent. When 1-ft2 quadrats were harvested by hand in an attempt to recover tubersattached to actively growing shoots, there were significantly fewer tubers in the Eptam-treated plots compared to the disked-only plots (Table 2). The ratio of tubers in theEptam-treated plots compared to the disked-only plots was much smaller than from thecore samples. This demonstrates that the Eptam was reducing the production of newyellow nutsedge tubers, and likely inhibiting the germination of tubers that were presentwhen the Eptam was applied. Sampling from nonreplicated strips in the field suggeststhat any additional management of yellow nutsedge growth decreased the total numberof tubers produced. Disking once had the highest number of tubers followed by diskingtwice, and then by disking once and then applying Eptam and incorporating with asecond disking.

This research demonstrated that significant numbers of yellow nutsedge tubers can beproduced following wheat harvest. Management of yellow nutsedge growth followingwheat harvest is essential to prevent the production of additional tubers and thepotential buildup of tubers to levels that will make yellow nutsedge control difficult infollowing crops. The use of Eptam as a chemical fallow treatment significantly reducedyellow nutsedge shoot and tuber production.

4

251

Table 1. Yellow nutsedge shoot and tuber numbers in response to diskingplus disking, Malheur Experiment Station, Ontario, OR, 2004.

and Eptam®

Yellow nutsedge shoots Yellow nutsedge tubersTreatment Sept. 16 Oct. 4 Initial Final Change

no/yd2 %

Disking only 17 23 45 79 + 94

Eptam + Disking 7 14 45 48 + 7

Table 2. Yellow nutsedgtaken from hand-harvestOntario, OR, 2004.

e shooted qua

and tuber numbers in response to diskingdrats on October 21, Malheur Experiment

andStation,

TreatmentYellow nutsedge

Shoots Tubersno/yd2

Disking only 37 33

Eptam + Disking 11 7

Table 3. Average yeEptam®, taken fromMalheur Experiment

110w nutsedge shoot and tuber numbers in response to disking andnon replicated strips adjacent to the trial area on October 6,Station, Ontario, OR, 2004.

TreatmentYellow nutsedge

Shoots Tubers

Disked onceno/ft2

60 47

Disked twice 32 20

Disked followed by Eptam + Disking 14 5

252

APPENDIX A. HERBICIDES AND ADJUVANTS

Trade Name Common or Code Name Manufacturer

Basagran bentazon BASF Ag ProductsBetamix desmedipham + phenmedipham Bayer CropScienceBronate bromoxynil + MCPA Bayer CropScienceBuctril bromoxynil Bayer CropScienceCallisto mesotrione SyngentaCasoron 4G dichlobenil CromptonChateau flumioxazin ValentClarion nicosulfuron + rimsulfuron DuPontCommand clomazone FMCDacthal DCPA SyngentaDistinct diflufenzopyr + dicamba BASF Ag ProductsDual, Dual Magnum, metolachlor SyngentaDual II MagnumDyne-Amic proprietary surfactant blend Helena ChemicalEptam EPTC SyngentaGoal, Goal 2XL oxyflurorfen Dow AgrosciencesGramoxone paraquat dichioride SyngentaKarmex diuron Griffin LLCKerb pronamide Dow AgrosciencesMatrix rimsulfuron DupontOption foramsulfuron Bayer CropScienceOutlook dimethenamid-p BASF Ag ProductsNortron ethofumesate Bayer CropSciencePermit halosulfuron MonsantoPoast, Poast HC sethoxydim BASF Ag ProductsProgress desmedipham + phenmedipham Bayer CropScience

+ ethofumesateProwl, Prowl H2O pendimethalin BASF Ag ProductsQuest proprietary spray additive Helena ChemicalRoundup, glyphosate MonsantoRoundup UltraSandea halosulfuron Gowan CompanySencor metribuzin Bayer CropScienceSinbar terbacil DuPontSpartan sulfentrazone FMCStinger clopyralid Dow Ag rosciencesTreflan triflu ralin Dow Ag rosciencesUpBeet triflusulfuron DupontValor flumioxazin Valent

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APPENDIX B. INSECTICIDES, FUNGICIDES, AND NEMATICIDES

Trade Name Common or Code Name Manufacturer

Asana esfenvalerate DuPontAza-Direct azadirachtin Gowan CompanyBayleton triad imefon Bayer CropScienceBravo, Bravo Weather Stik chlorothalanil SyngentaCaptan captan Micro FloCapture bifenthrin FMCCounter 20 CR, Counter 15G terbufos BASF Ag ProductsDiazinon AG500 diazinon Helena ChemicalDibrom naled UAPDimethoate dimethoate SeveralDithane mancozeb Dow AgroscienceEcozin azadirachtin AmvacGaucho imidacloprid Gowan CompanyGuthion azinphos-methyl Bayer CropScienceHeadline pyraclostrobin BASF Ag ProductsKocide copper hydroxide GriffinLannate methomyl DuPontLorsban, Lorsban 15G chlorpyrifos Dow AgroscienceMalathion malathion UAPMessenger harpin protein Eden BioScienceMetasystox-R oxydemeton-methyl Gowan CompanyMSR oxydemeton-methyl Gowan CompanyMustang zeta-cypermethrin FMCPenncap-M methyl parathion Cerexagri, Inc.Ridomil Gold MZ metalaxyl SyngentaSuccess spin osad Dow Agrosci.Super-Six liquid sulfur Plant Health Tech.Telone C-17 dichloropropene + chloropicrin Dow Agrosci.Telone II dichloropropene Dow Agrosci.Temik 15G aldicarb Bayer CropscienceThimet phorate BASF Ag ProductsTopsin M thiophanate-methyl Cerexagri, Inc.Tops-MZ thiophanate-methyl UAPVapam metham sodium AmvacVydate, Vydate L oxamyl DuPontWarrior cyhalothrin SyngentaWarrior I cyhalothrin Syngenta

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APPENDIX C. COMMON AND SCIENTIFIC NAMES OF CROPS,FORAGES AND FORBS

Common names Scientific names

alfalfa Medicago sativa

barley Hordeum vulgare

bluebunch wheatgrass Pseudoroegneria spicata

corn Zea mays

dry edible beans Phaseolusspp.

Great Basin wildrye Leymus cinereus

hicksii yew Taxus x media

onion A/hum cepa

pacific yew Taxus brevifolia

poplar trees, hybrid Populus deltoides x P. nigra

potato Solanum tube rosum

Russian witdrye PsathyrostachysjunceaSiberian wheatgrass Agroyron fragilesoybeans Glycine max

spearmint, peppermint Mentha sp.

sugar beet Beta vulgaris

supersweet corn Zea mays

sweet corn Zea maystriticale Triticum x Secale

western yarrow Achillea milhifohium

wheat Triticum aestivum

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APPENDIX D. COMMON AND SCIENTIFIC NAMES OF WEEDSCommon names Scientific names

annual sowthistle Sonchus oleraceus

common Iambsquarters Chenopodium album

downy brome Bromus tectorum

dodder Cuscutasp.

green foxtail Setaria viridis

redroot pigweed Amaranthus retroflexus

barnyardg rass Echinochloa crus-galli

kochia Kochia scoparia

hairy nightshade Solanum sarrachoidesPowell amaranth Amaranthus powellllprickly lettuce Lactuca serriola

Russian knapweed Acroption repensyellow nutsedge Cyperus esculentus

APPENDIX E. COMMON AND SCIENTIFIC NAMES OF DISEASES AND INSECTSCommon names Scientific namesDiseasesonion black mold Aspergillus nigeronion neck rot, (gray mold) Botrytis all/ionion plate rot Fusarium oxysporumonion translucent scalepotato late blight Phytophthora infestans

Insectscereal leaf beetle Oulema melanopuslygus bug Lygus hesperusonion maggot Delia antiquaonion thrips Thrips tabacipea aphid Acyrthosiphon p/sumseed corn maggot Della platurastinkbug Pentatomidae sp.spidermite Tetranychus sp.sugar beet root maggot Tetanops myopae form/swillow sharpshooter Graphocephala con fluens (U hler)

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