agsci.oregonstate.edu · The information in this report is for the purpose of informing cooperators...

MALHEUR EXPERIMENT STATION ANNUAL REPORT 2012, Ext/CrS 144

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Oregon State University, Malheur Experiment Station Annual Report 2012, Department of Crop and Soil Science Ext/CrS 144, July 2013, edited by Clinton C. Shock.

For additional copies of this publication Clinton C. Shock Malheur Experiment Station 595 Onion Avenue Ontario, OR 97914 For additional information, please check our website http://www.cropinfo.net

Agricultural Experiment Station Oregon State University Department of Crop and Soil Science Ext/CrS 144, July 2013

Malheur Experiment Station Annual Report 2012 The information in this report is for the purpose of informing cooperators in industry, colleagues at other universities, and others of the results of research in field crops. Reference to products and companies in this publication is for specific information only and does not endorse or recommend that product or company to the exclusion of others that may be suitable. Nor should information and interpretation thereof be considered as a recommendation for application of any pesticide. Pesticide labels should always be consulted and followed before any pesticide use. Common names and manufacturers of chemical products used in the trials reported here are contained 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 names of diseases and insects are listed in Appendix E.

TABLE OF CONTENTS WEATHER

2012 Weather Report ---------------------------------------------------------------------- 1

ONION

2012 Onion Variety Trials ----------------------------------------------------------------- 12

Onion Production from Transplants and Sets ---------------------------------------- 26

Onion Variety Response to Plant Population and Irrigation System ----------- 35

Insecticide Rotations for Thrips Control in Onions, 2012-------------------------- 63

Alternative Methods for Thrips Control in Onions, 2012 --------------------------- 70

Post-emergence Herbicide Combinations for Weed Control in Direct-seeded Onion ---------------------------------------------------------------------------------

76

Evaluation of Sustain® Adjuvant for Improved Herbicide Weed Efficacy in Direct-seeded Onion ------------------------------------------------------------------------

82

Evaluation of Zidua® (Pyroxasulfone) and Warrant® (Acetochlor) for Weed Control In Direct-seeded Onion --------------------------------------------------------- 87

POTATO AND SWEET POTATO

2012 Potato Variety Trials ----------------------------------------------------------------- 93

Response Of Several Rotational Crops To Fomesafen (Reflex®) Herbicide Soil Residues --------------------------------------------------------------------------------- 112

Sweet Potato Cultivar Performance and Irrigation Criteria for the Treasure Valley -------------------------------------------------------------------------------------------- 121

WILDFLOWER AND NATIVE PLANT SEED PRODUCTION

Direct Surface Seeding Strategies for the Establishment of Two Native Legumes of the Intermountain West ---------------------------------------------------- 132

Eight Years Evaluating the Irrigation Requirements for Native Wildflower Seed Production ------------------------------------------------------------------------------ 138

Preliminary Estimates of the Irrigation Requirements for Novel Native Wildflower Seed Production --------------------------------------------------------------- 160

Tolerance of Sulfur-flower Buckwheat (Eriogonum umbellatum) to Rates and Mixtures of Postemergence Herbicides, 2008–2012 ------------------------- 173

TABLE OF CONTENTS (continued)

YELLOW NUTSEDGE BIOLOGY AND CONTROL

Biology, Development, and Tuber Production of Two Yellow Nutsedge (Cyperus esculentus) Varieties in the Treasure Valley ---------------------------- 176

Herbicide Combinations and Adjuvants for Yellow Nutsedge Control in Glyphosate-resistant Sugar Beet -------------------------------------------------------- 184

APPENDICES

A. Herbicides and Adjuvants ------------------------------------------------------------- 193

B. Insecticides, Fungicides, and Nematicides --------------------------------------- 194

C. Common and Scientific Names of Crops, Forages, and Forbs -------------- 195

D. Common and Scientific Names of Weeds ---------------------------------------- 196

E. Common and Scientific Names of Diseases, Physiological Disorders, Insects, and nematodes -------------------------------------------------------------------- 197

CONTRIBUTORS AND COOPERATORS MALHEUR EXPERIMENT STATION ANNUAL REPORT

2012 RESEARCH MALHEUR EXPERIMENT STATION Feibert, Erik Senior Faculty Research Assistant Felix, Joel Assistant Professor of Weed Science Ishida, Joey Bioscience Research Technician Jones, Janet Office Specialist Saunders, Lamont Bioscience Research Technician Shock, Clinton Professor, Director MALHEUR EXPERIMENT STATION, STUDENTS Barlow, Kenzie Research Aide Cassity, Branden Research Aide Doniger, Alison Graduate Student Foley, Kelly Graduate Student Harden, Jackie Research Aide Lugeiyamu, Felix Research Aide Lugeiyamu, Oliver Research Aide

Parris, Cheryl Graduate Student Rock, Ashley Research Aide Ross, Ryan Research Aide OREGON STATE UNIVERSITY, CORVALLIS, AND OTHER STATIONS Bassinette, John Senior Faculty Research Assistant, Dept. of Crop and Soil Science Charlton, Brian Faculty Research Assistant, Klamath Falls Karow, Russell Professor, Dept. of Crop and Soil Science Reitz, Stuart Professor, Malheur County Extension Service

Sathuvalli, Sagar Assistant Professor, Hermiston Vales, Isabel Associate Professor, Dept. of Crop and Soil Science

Yilma, Solomon Senior Faculty Research Assistant, Dept. of Crop and Soil Science OTHER UNIVERSITIES Brown, Brad Extension Specialist, University of Idaho, Parma, ID Burke, Ian Associate Professor, Washington State University, Pullman, WA Mohan, Krishna Professor, University of Idaho, Parma, ID Morishita, Don Associate Professor, University of Idaho, Twin Falls, ID Neufeld, Jerry Associate Professor, University of Idaho, Caldwell, ID Norberg, O. Steve Regional Forage Specialist, Washington State University, Pasco, WA Novy, Rich Research Geneticist/Potato Breeder, USDA, Aberdeen, ID O'Neill, Mick Superintendent, New Mexico State University, Farmington, NM

Pappu, Hanu Associate Professor, Washington State University, Pullman, WA Reddy, Steven Extension Educator, University of Idaho, Weiser, ID Sampangi, Ram Extension Support Scientist, University of Idaho, Parma, ID OTHER PERSONNEL COOPERATING ON SPECIAL PROJECTS Anderson, Brian Clearwater Supply, Inc., Othello, WA Boydston, Rick USDA-ARS, Prosser, WA Breidenbach, John Ontario Chamber of Commerce, Ontario, OR Brown, Charles USDA-ARS, Prosser, WA

Bushman, Shaun USDA-ARS Forage and Range Research Lab, Logan, UT Cane, Jim UDSA-ARS, Bee Lab, Logan, UT Carlson, Wayne The Teff Company, Caldwell, ID

Chamberlin, Jay Owyhee Irrigation District, Nyssa, OR Corn, Dan Cooperating Grower, Ontario, OR

Donar, Larry Fresno Valves and Castings, Inc., Kennewick, WA Erstrom, Jerry Malheur Watershed Council, Ontario, OR Faw, Gary Malheur County Soil & Water Conservation District, Ontario, OR

Foote, Paul Amalgamated Sugar Co., Paul, ID Gonzalez, Don Bureau of Land Management, Vale, OR Green, Adena Coordinator, Owyhee Watershed Council, Adrian, OR Hansen, Mike M.K. Hansen Co., East Wenatchee, WA Hawkins, Al Irrometer Co., Inc., Riverside, CA Hill, Carl Owyhee Watershed Council, Ontario, OR Jeffries, Dale KSRV Impact Radio Group, Ontario, OR Jemmett, Eric Jemmett Consulting and Research Farm, Parma, ID Jensen, Scott USDA Forest Service Shrub Science Lab, Provo, UT Johnson, Doug USDA-ARS Forage and Range Research Lab, Logan, UT Kitamura Farms Cooperating Grower, Ontario, OR Klauzer, Jim Clearwater Supply, Inc., Ontario, OR Komoto, Bob Ontario Produce, Ontario, OR Larsen, Lynn Natural Resources Conservation Service, Ontario, OR Leiendecker, Karen Oregon Watershed Enhancement Board, La Grande, OR Love, Byron USDA-ARS, Bee Lab, Logan, UT

Lowe, Jeff Scotts Company, Marysville, OH Mann, David Infinity Pharmaceuticals, Inc., Cambridge, MA

McPherson, Joe Infinity Pharmaceuticals, Inc., Cambridge, MA Miller, Donald Producer’s Choice Seed, Nampa, ID Mittlestadt, Bob Clearwater Supply, Inc., Othello, WA Montgomery, Tonia The Biz Zone, Fruitland, ID

Morrison, Eric Jordan Valley Weed Coordinator, Jordan Valley, OR Murata, Warren Cooperating Grower, Ontario, OR Nakada, Vernon Cooperating Grower, Ontario, OR Page, Gary Malheur County Weed Supervisor, Vale, OR

Pellant, Mike Bureau of Land Management, Boise, ID Penning, Tom Irrometer Co., Inc., Riverside, CA Polhemus, Dave Andrews Seed Co., Ontario, OR Reid, Trey Ag Concepts Corp., Boise, ID Richardson, Phil Oregon Dept. of Environmental Quality, Pendleton, OR Rowe, Linda Malheur County Soil & Water Conservation District, Ontario, OR Saito, Jeff Cooperating Grower, Ontario, OR Saito, Reid Cooperating Grower, Ontario, OR Shaw, Nancy USDA Forest Service, Boise, ID Simerly, Bob McCain Foods, Fruitland, ID Stander, J.R. Betaseed, Inc., Kimberly, ID OTHER PERSONNEL COOPERATING ON SPECIAL PROJECTS (continued) Taberna, John Western Laboratories, Inc., Parma, ID Weidemann, Kelly Malheur Watershed Council, Ontario, OR Wettstein, Lou Cooperating Grower, Ontario, OR Youtie, Berta Eastern Oregon Stewardship Services, Prineville, OR GROWERS ASSOCIATIONS SUPPORTING RESEARCH Idaho-Eastern Oregon Onion Committee Malheur County Potato Growers Nyssa-Nampa Beet Growers Association Oregon Potato Commission Oregon Wheat Commission PUBLIC AGENCIES SUPPORTING RESEARCH Agricultural Research Foundation Bureau of Land Management Lower Willow Creek Working Group Malheur County Soil and Water Conservation District Malheur Watershed Council Oregon Department of Agriculture Oregon Watershed Enhancement Board Owyhee Watershed Council USDA Cooperative State Research, Education, and Extension Service USDA Forest Service

COMPANY CONTRIBUTORS Absorbent Technologies, Inc. ACH Seeds Amalgamated Sugar Co. American Takii, Inc. Andrews Seed, Inc. BASF Corp. Bayer CropScience Bejo Seeds, Inc. Betaseed, Inc. Crookham Seed Co. D. Palmer Seeds Dow AgroScience FMC Corp. Global Genetics Gowan Co. Hilleshog/Syngenta Holly Hybrids Infinity Pharmaceuticals, Inc. Irrometer Co., Inc. J.R. Simplot Co. McCain Foods Monsanto Co. Nunhems USA, Inc. Producers’ Choice Sakata Seed America Seedex Seminis Vegetable Seed, Inc. Syngenta Crop Protection Treasure Valley Seed Co. TKI NovaSource

Valent BioSciences Corp. Valent USA W-L Research Wilbur-Ellis Winfield Solutions

2012 WEATHER REPORT Erik B. G. Feibert and Clinton C. Shock, Malheur Experiment Station, Oregon State University Ontario, OR Introduction Air temperature and precipitation have been recorded daily at the Malheur Experiment Station since July 20, 1942. Installation of additional equipment in 1948 allowed for evaporation and wind measurements. A soil thermometer at 4-inch depth was added in 1967. Since 1962, the Malheur Experiment Station has participated in the Cooperative Weather Station system of the National Weather Service. The daily readings from the station are reported to the National Weather Service forecast office in Boise, Idaho. A biophenometer, to monitor degree days, and pyranometers, to monitor total solar and photosynthetically active radiation, were added in 1985. Starting in June 1997, the daily weather data and the monthly weather summaries have been posted on the Malheur Experiment Station web site at <www.cropinfo.net>. On June 1, 1992, in cooperation with the U.S. Department of the Interior, Bureau of Reclamation, a fully automated weather station, linked by satellite to the Northwest Cooperative Agricultural Weather Network (AgriMet) computer in Boise, Idaho, began transmitting data from Malheur Experiment Station. The automated Agrimet station continually monitors air temperature, relative humidity, dew point temperature, precipitation, wind run, wind speed, wind direction, solar radiation, and soil temperature at 8-inch and 20-inch depths. Data are transmitted via satellite to a computer in Boise every 4 hours and are used to calculate daily Malheur County crop water-use estimates. The AgriMet database can be accessed at www.usbr.gov/pn/agrimet and from links on the Malheur Experiment Station web page at www.cropinfo.net.

Materials and Methods The ground under and around the weather stations was bare until October 17, 1997, when it was covered with turfgrass. The grass is irrigated with subsurface drip irrigation. The manually observed weather data are recorded each day at 8:00 a.m. Consequently, the data in the tables of daily observations refer to the previous 24 hours. Evaporation is measured from April through October as inches of water evaporated from a standard class A pan (10 inches deep by 4-ft diameter) over 24 hours. Evapotranspiration (ETc) for each crop is calculated by the AgriMet computer using data from the AgriMet weather station and the Kimberly-Penman equation (Wright 1982). Agrimet calculates reference evapotranspiration (ET0) for a theoretical 12- to 20-inch-tall crop of alfalfa assuming full cover for the whole season. Evapotranspiration for all crops is calculated using ET0 and crop coefficients for each crop. These crop coefficients vary throughout the growing season based on the plant growth stage (crop cover). The crop coefficients are tied to the plant growth stage by three dates: start, full cover, and termination dates. Start dates are the beginning of vegetative growth in the spring for perennial crops or the emergence date for row crops. Full cover dates

2012 Weather Report 1

are typically when plants reach full foliage. Termination dates are defined by harvest, frost, or dormancy. Alfalfa mean ETc is calculated for an alfalfa crop using ET0 and assuming a 15 percent reduction to account for cuttings. Wind run is measured as total wind movement in miles over 24 hours at 24 inches above the ground. Weather data averages in the tables, except evapotranspiration, refer to the years preceding and up to, but not including, the current year.

2012 Weather The total precipitation for 2012 (9.1 inches) was lower than the 10-year (10.7 inches) and 68-year (10.2 inches) averages (Table 1). Total snowfall for 2012 (4.0 inches) was lower than the 10-year average (13.8 inches) and the 68-year average (17.9 inches) (Table 2). The highest air temperature for 2012 was 102°F on July 10, 12, and 13 (Table 3). The lowest temperature for the year was 4°F on December 28. The total number of accumulated growing degree-days (50 to 86°F) in 2012 was 5 percent higher than the 26-year average (Table 4, Fig. 1). April, July, August, and September had a higher number of growing degree-days than the 26-year average (Table 4). The total number of degree-days in the above-optimal range (86 to 104°F) in July and August was higher than the 22-year average (Table 5). Total wind runs for all months, except April, September, and October were higher than the 10-year and 64-year averages (Table 6). Total pan evaporation for 2012 was close to the 10-year average and higher than the 64-year average (Table 7). In 2012, total accumulated reference evapotranspiration and ETc estimated values for all crops except winter grain were higher than the 20-year averages (Table 8). The average monthly maximum and minimum 4-inch soil temperatures for all months were close to the 10-year average (Table 9). The last spring frost (≤32°F) occurred on April 29, the same as the 36-year-average date of April 29; the first fall frost occurred on October 4, 3 days earlier than the 36-year-average date of October 7 (Table 10). No local weather records were broken in 2012 (Table 11).

References Wright, J.L. 1982. New evapotranspiration crop coefficients. Journal of Irrigation and Drainage

Division, American Society of Civil Engineers 108:57-74.


Table 1. Monthly precipitation at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2012.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total -------------------------------------------------------- inches --------------------------------------------------------

1990 0.49 0.69 0.29 1991 0.59 0.44 0.88 0.81 1.89 1.09 0.01 0.04 0.35 1.01 1.71 0.43 9.25 1992 0.58 1.36 0.25 0.74 0.21 1.43 0.36 0.01 0.09 0.95 1.15 1.51 8.64 1993 2.35 1.02 2.41 2.55 0.70 1.55 0.18 0.50 0.00 0.80 0.64 0.60 13.30 1994 1.20 0.57 0.05 1.02 1.62 0.07 0.19 0.00 0.15 1.23 2.46 1.49 10.05 1995 2.67 0.28 1.58 1.16 1.41 1.60 1.10 0.13 0.07 0.57 0.88 2.56 14.01 1996 0.97 0.86 1.03 1.19 2.39 0.12 0.32 0.31 0.59 0.97 1.18 2.76 12.69 1997 2.13 0.17 0.25 0.66 0.67 0.86 1.40 0.28 0.40 0.43 1.02 0.94 9.21 1998 2.26 1.45 0.95 1.43 4.55 0.36 1.06 0.00 1.00 0.04 1.07 1.11 15.28 1999 1.64 2.50 0.59 0.23 0.28 1.02 0.00 0.09 0.00 0.40 0.49 0.73 7.97 2000 2.01 2.14 0.97 0.72 0.28 0.26 0.03 0.06 0.39 1.74 0.38 0.66 9.64 2001 1.15 0.41 1.11 0.70 0.37 0.64 0.32 0.00 0.10 0.68 1.33 1.00 7.81 2002 0.77 0.27 0.49 0.77 0.09 0.60 0.14 0.10 0.36 0.29 0.44 1.86 6.18 2003 1.46 0.48 0.99 1.12 1.52 0.24 0.36 0.11 0.15 0.02 0.86 1.47 8.78 2004 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 2005 0.41 0.12 1.66 0.80 2.94 1.02 0.22 0.06 0.14 1.38 1.58 3.92 14.25 2006 1.91 0.67 3.33 2.00 0.62 0.45 0.00 0.08 0.55 0.28 1.14 1.76 12.79 2007 0.07 0.95 0.12 0.82 0.47 0.63 0.03 0.15 0.92 0.68 1.07 1.56 7.47 2008 0.50 0.43 0.79 0.14 0.74 0.27 0.43 0.03 1.26 0.44 1.12 1.47 7.62 2009 0.65 0.43 0.86 0.13 1.47 2.27 0.09 1.39 0.02 1.24 0.63 1.82 11.00 2010 2.13 1.19 0.59 1.21 1.18 1.95 0.02 0.86 0.19 1.16 1.09 4.19 15.76 2011 1.05 0.42 2.97 0.44 2.61 0.81 0.19 0.02 0.08 1.59 0.57 0.45 11.20 2012 1.65 0.49 1.36 1.03 0.77 0.45 0.00 0.04 0.10 0.83 1.13 1.25 9.10

10-yr avg. 1.08 0.65 1.21 0.84 1.33 0.87 0.16 0.34 0.42 0.91 0.94 1.95 10.70 69-yr avg. 1.27 0.93 0.98 0.78 1.09 0.83 0.22 0.35 0.44 0.75 1.14 1.37 10.15

Table 2. Annual snowfall totals (inches) at the Malheur Experiment Station, Oregon State University, Ontario, OR, 2001-2012.

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 10-yr avg.

69-yr avg.

15.5 11.5 4.5 24.0 13.5 12.3 3.8 26.0 13.8 28.0 1.0 4.0 13.8 17.9


Table 3. Maximum and minimum air temperatures by month, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Month Highest Lowest 2012 avg. 10-yr avg. 68-yr avg. --------------------------------- oF -------------------------------

Jan Max 54 34 42 36 35 Min 39 14 25 24 20

Feb Max 57 35 47 44 43 Min 35 19 27 26 25

Mar Max 69 42 56 56 55 Min 43 22 33 33 31

Apr Max 89 50 67 63 64 Min 55 23 39 38 37

May Max 90 54 72 73 74 Min 54 33 45 46 45

Jun Max 94 54 80 82 82 Min 60 37 49 53 52

Jul Max 102 85 95 94 92 Min 70 48 61 60 58

Aug Max 101 82 95 90 90 Min 66 47 57 56 56

Sep Max 93 69 83 81 80 Min 57 37 46 47 46

Oct Max 86 41 64 66 65 Min 51 24 34 39 37

Nov Max 66 35 50 49 48 Min 43 16 30 29 28

Dec Max 60 25 42 40 37 Min 42 4 24 24 22


Figure 1. Cumulative growing degree-days (50-86°F) over time for years with lowest (1993) and highest (2003) totals since 1990, compared to 2011, 2012, and to the 22-year average (1990-2011), Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Table 4. Monthly total growing degree-days (50-86°F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1986-2012.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec total 1986 0 16 85 119 338 639 650 796 296 158 14 0 3111 1987 0 0 43 275 423 547 641 649 486 223 29 2 3318 1988 0 5 51 180 318 585 911 691 376 309 20 0 3446 1989 0 0 13 184 272 549 733 581 389 117 14 0 2852 1990 2 7 79 239 261 497 734 635 585 38 0 0 3077 1991 0 13 16 124 212 389 776 718 436 194 1 0 2879 1992 0 13 106 202 482 574 639 704 385 174 4 0 3283 1993 0 0 23 81 423 358 464 524 408 252 6 0 2539 1994 0 2 92 189 369 523 794 774 509 144 2 0 3398 1995 0 29 32 106 293 433 680 588 472 101 3 10 2747 1996 0 5 53 135 243 446 805 658 364 194 18 2 2923 1997 4 0 81 117 419 509 661 706 481 157 20 0 3154 1998 0 2 52 112 68 571 802 749 515 151 16 4 3042 1999 0 2 43 72 329 459 683 703 416 184 30 0 2921 2000 0 4 36 194 342 536 751 743 368 133 2 0 3109 2001 0 0 63 126 401 488 715 761 472 155 27 0 3208 2002 0 2 32 137 319 562 805 621 437 142 14 2 3073 2003 0 4 72 112 319 594 846 754 448 281 11 2 3443 2004 0 0 115 187 311 607 776 680 365 180 4 0 3225 2005 0 7 59 126 286 419 749 733 383 133 4 0 2899 2006 0 4 22 131 364 599 866 668 394 151 31 0 3230 2007 0 7 99 146 405 551 871 682 398 115 20 0 3294 2008 0 0 13 86 333 504 774 700 387 144 16 2 2959 2009 0 2 27 144 369 486 758 670 535 72 13 0 3074 2010 0 0 45 104 191 439 716 632 423 205 25 0 2780 2011 0 4 11 56 202 400 697 760 508 158 4 2 2800 2012 0 4 52 178 283 463 823 767 463 155 25 4 3216

Avg. 1986 to 2011 0 5 52 142 319 510 742 688 432 164 13 1 3069


Table 5. Monthly total degree-days in the above-ideal (86-104°F) range, Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2012.

Year Apr May Jun Jul Aug Sep Oct Total 1990 0 0 13 56 41 14 0 124 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 2005 0 0 4 43 36 4 0 86 2006 0 5 13 81 23 5 0 128 2007 0 0 14 79 29 5 0 128 2008 0 4 9 41 31 0 0 85 2009 0 4 5 41 32 11 0 94 2010 0 0 2 32 25 0 0 59 2011 0 0 4 20 38 11 0 73 2012 0 0 4 58 47 4 0 112

Mean (1990-2011) 0 2 8 43 33 5 0 91 Table 6. Daily and monthly wind-run, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Daily Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ------------------------------------------- miles/day ----------------------------------------------- Mean 63 73 109 72 72 68 59 55 40 40 45 70 Max. 196 210 239 229 186 134 110 104 131 158 179 396 Min. 16 15 24 28 21 17 28 21 8 12 3 6 Monthly total -------------------------------------------- miles/month ------------------------------------------------

2012 1942 2118 3372 2150 2244 2045 1842 1696 1188 1228 1349 2155 64-yr average

2192 1966 1606 1498 1342 1256 1311

10-yr average 1354 1536 2339 2431 2126 1800 1589 1400 1222 1426 1349 1430


Table 7. Daily and monthly pan-evaporation, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Totals Apr May Jun Jul Aug Sep Oct Total Daily ---------------------- inches/day ------------------------- Mean 0.20 0.27 0.33 0.41 0.37 0.22 0.12 Max. 0.45 0.56 0.50 0.57 0.52 0.46 0.32 Min. 0.02 0.09 0.10 0.25 0.22 0.05 0.00

Monthly ---------------------- inches/month ------------------------- 2012 6.14 8.29 9.96 12.61 11.35 6.74 3.71 58.80

10-yr avg. 6.26 8.53 10.07 12.48 10.27 7.06 4.17 58.84 64-yr avg. 5.69 7.82 9.07 11.33 9.72 6.41 3.37 53.41

Table 8. Total accumulated reference evapotranspiration (ET0) and estimated crop evapotranspiration (ETc) (acre-inches/acre), Malheur Experiment Station, Oregon State University, Ontario, OR, 1992-2012.

ETo

Alfalfa (mean)

Winter grain

Spring grain

Sugar beet Onion Potato

Dry bean

Field corn

Poplar Year Yr. 1 Yr. 2 Yr. 3 +

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 31.6 31.9 22.4 29.3 24.3 37.9 45.9 2004 52.8 43.5 27.8 30.6 34.3 30.2 27.9 22.1 28.4 23.3 36.3 44.1 2005 53.8 44.5 26.5 27.0 36.0 32.8 30.2 20.0 29.2 24.3 37.8 45.3 2006 57.7 47.9 24.4 31.4 38.5 33.8 29.4 23.9 30.3 26.3 41.0 49.3 2007 59.0 47.2 27.6 26.7 38.9 33.7 29.7 24.5 30.5 25.7 40.1 48.6 2008 58.0 46.4 28.1 30.4 36.4 32.7 30.0 24.0 30.4 23.3 36.5 44.5 2009 58.1 42.5 26.3 28.4 34.7 28.4 27.6 20.3 26.7 22.6 35.2 42.7 2010 51.5 41.9 21.0 26.8 33.4 28.9 27.7 21.1 26.7 22.2 34.5 41.4 2011 51.0 41.9 23.3 25.8 34.4 29.2 27.5 22.8 28.0 23.6 36.8 44.5 2012 57.3 45.3 23.6 27.6 36.4 31.5 31.6 24.0 31.2 25.3 39.4 47.4

Avg. inch 55.3 42.8 24.5 26.8 34.8 29.8 27.8 21.4 28.0 24.0 37.4 45.1

mm 1404 1086 623 680 883 758 705 543 710 610 950 1147


Table 9. Monthly soil temperature at 4-inch depth, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

2012

Month Average Highest Lowest 10-yr avg. 45-yr avg.

--------------------------------- oF -------------------------------

Jan Max 34 37 30 33 33 Min 33 35 28 32 32

Feb Max 36 39 34 35 37 Min 35 37 32 33 34

Mar Max 42 46 36 43 49 Min 40 45 34 40 40

Apr Max 49 57 41 50 60 Min 46 56 37 46 47

May Max 57 64 50 60 71 Min 53 59 48 55 57

Jun Max 63 67 56 68 80 Min 60 63 54 62 66

Jul Max 72 74 68 75 88 Min 68 72 65 68 73

Aug Max 72 74 69 73 86 Min 69 72 64 67 73

Sep Max 64 68 61 65 75 Min 62 67 57 61 63

Oct Max 54 62 46 55 60 Min 52 60 44 51 51

Nov Max 46 51 40 43 44 Min 45 50 39 41 39

Dec Max 39 45 33 35 34 Min 38 45 32 33 33


Table 10. Last and first frost (32°F) dates and number of frost-free days, Malheur Experiment Station, Oregon State University, Ontario, OR, 1976-2012.

Year Date of last frost Date of first frost Total frost-free days Spring Fall

1976 23 Apr 5 Oct 165 1977 20 Apr 22 Sep 155 1978 23 Apr 14 Oct 174 1979 20 Mar 27 Oct 221 1980 13 Apr 17 Oct 187 1981 14 Apr 1 Oct 170 1982 5 May 5 Oct 153 1983 27 Apr 20 Sep 146 1984 7 May 25 Sep 141 1985 13 May 30 Sep 140 1986 23 May 12 Oct 142 1987 21 Apr 11 Oct 173 1988 2 May 30 Oct 181 1989 19 May 13 Sep 117 1990 8 May 7 Oct 152 1991 30 Apr 4 Oct 157 1992 24 Apr 14 Sep 143 1993 20 Apr 11 Oct 174 1994 15 Apr 6 Oct 174 1995 16 Apr 22 Sep 159 1996 6 May 23 Sep 140 1997 3 May 8 Oct 158 1998 18 Apr 17 Oct 182 1999 11 May 28 Sep 140 2000 12 May 24 Sep 135 2001 29 Apr 10 Oct 164 2002 8 May 12 Oct 157 2003 19 May 11 Oct 145 2004 16 Apr 24 Oct 191 2005 15 Apr 6 Oct 174 2006 19 Apr 22 Oct 186 2007 4 May 11 Oct 160 2008 2 May 13 Oct 164 2009 13 May 1 Oct 141 2010 7 May 12 Oct 158 2011 4 May 25 Oct 174 2012 29 Apr 4 Oct 158

Avg. 1976 - 2011 29 Apr 7 Oct 161


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

Record event Measurement Date ------------------------------------------ Since 1943 ------------------------------------------------

Highest annual precipitation 16.87 inches 1983 Lowest annual precipitation 5.16 inches 1949 Highest monthly precipitation 4.55 inches May 1998 Highest June precipitation 2.27 inches June 2009 Highest December precipitation 4.19 inches Dec 2010 Highest 24-hour precipitation 1.52 inches Sep 14, 1959 Highest annual snowfall 40 inches 1955 Highest 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 35 days 1985

------------------------------------------ Since 1967 ------------------------------------------------ Lowest soil temperature at 4-inch depth 12°F Dec 24, 25, and 26, 1990

------------------------------------------ Since 1986 ----------------------------------------------- Most yearly growing degree-days 3,446 degree-days 1988 Fewest yearly growing degree-days 2,539 degree-days 1993 Fewest growing degree-days in March 11 2011 Fewest growing degree-days in April 56 2011 Highest reference evapotranspiration 59.0 inches 2007


2012 ONION VARIETY TRIALS Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR Introduction The objectives of the onion variety trials were to evaluate yellow, white, and red onion varieties for disease, maturity, bolting, single centers, yield, and grade out of storage. Two early season yellow varieties were planted in March and were harvested and graded in mid-August. Forty-nine full-season varieties (40 yellow, 6 red, and 3 white) were planted in March, harvested in September 2012, and graded out of storage in January 2013. Each year, growers and seed industry representatives have the opportunity to examine the varieties at our annual Onion Variety Field Day in late August and during onion grading in early January. Varieties are evaluated objectively for maturity, bolting, onion thrips, yield, grade, single centers, and storability. Varieties are evaluated subjectively for iris yellow spot virus, bulb shape, bulb shape uniformity, color, and skin retention. Materials and Methods Onions were grown on an Owyhee silt loam with a pH of 7.6 and 2.1 percent organic matter, previously planted to wheat. In the fall of 2011, the wheat stubble was shredded and the field was irrigated. Based on a soil analysis, 100 lb of phosphorus/acre, 200 lbs of sulfur/acre, 1,000 lbs of gypsum/acre, and 1 lb of boron/acre were broadcast. The field was then disked, moldboard plowed, and groundhogged. On September 25, the field was fumigated with Vapam® (metam sodium) at 15 gal/acre and bedded at 22 inches. Both the full-season trial and the early maturing trial were planted on March 27, adjacent to each other, and in plots 4 double rows wide and 27 ft long. The early maturing trial had 2 varieties from 2 seed companies (Tables 1 and 2) and the full-season trial had 46 varieties from 9 seed companies (Tables 3 and 4). The experimental designs for both trials were randomized complete blocks with five replicates. A sixth nonrandomized replicate was planted for demonstrating onion variety performance to growers and seed company 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. Planting was done with customized John Deere Flexi Planter units equipped with disc openers. Immediately after planting, the onions received a narrow band of Lorsban 15G® at 3.7 oz/1,000 ft of row (0.82 lb ai/acre), and the soil surface was rolled. Onion emergence started on April 16. On May 21, alleys 4 ft wide were cut between plots, leaving plots 23 ft long. On May 21-23, the seedlings were hand thinned to a plant population of 2 plants/ft of single row (6-inch spacing between individual onion plants, or 95,000 plants/acre). The onions were managed to minimize yield reductions from weeds, pests, diseases, water stress, and nutrient deficiencies. Roundup® at 1 lb ai/acre was broadcast on April 6 prior to onion emergence. On April 23, Prowl® H2O at 0.83 lb ai/acre (2 pt/acre) was applied for weed control. On June 1, Goal® at 0.19 lb ai/acre (12 oz/acre), Buctril® at 0.32 lb ai/acre (20 oz/acre), and

2012 Onion Variety Trials 12

Select® at 0.19 lb ai/acre (12 oz/acre) were applied for weed control. On June 12, Outlook® at 0.5 lb ai/acre (11 oz/acre) was applied for weed control. On May 31 and June 8, Movento® at 5 oz/acre was applied for thrips control. On June 18 and June 25, Radiant® at 10 oz/acre was applied for thrips control. The field received aerial applications of Lannate® at 0.9 lb ai/acre on July 14, July 21, August 3, and August 11 for thrips control. Based on analyses of root tissue samples taken on June 18 and July 2, a total of 250 lb nitrogen/acre and 0.4 lb boron/acre were applied during the season. Nitrogen was applied at 100 lb/acre as urea sidedressed to both sides of the bed on May 24. Nitrogen was applied at 50 lb/acre as water run URAN (urea + ammonium nitrate) on July 5, July 13, and July 20. The trial was furrow irrigated when the soil water tension at 8-inch depth reached 25 cb (1 cb = 1 kPa) (Shock et al. 2005, 2010). Starting in early June, soil water tension was monitored by six granular matrix sensors (Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside, CA) centered at 8-inch depth below the onion row. The sensors were automatically read three times a day with a datalogger (Irrometer Monitor Model 950 R1). The last irrigation was on August 31. The early maturing trial was evaluated for maturity on August 15. Onions in each plot were evaluated subjectively for maturity by visually rating the percentage of onions with the tops down and the percent dryness of the foliage. The number of bolted onion plants was counted in each plot. On June 4, onions in each plot of the full-season trial were evaluated for severity of injury in response to postemergence herbicide application on June 1. Each plot was given a subjective rating on a scale of 0 to 10 of increasing severity of leaf damage. The thrips counts on each of 15 plants in each plot were made on June 6 and June 28. Onions in each plot of the full-season trial were evaluated for maturity and severity of thrips leaf damage on August 15. For thrips leaf damage, each plot was given a subjective rating on a scale of 0 to 10 of increasing severity of leaf damage from thrips feeding. Onions in each plot were evaluated for severity of symptoms of iris yellow spot virus (IYSV) on August 22. Each plot was given a subjective rating on a scale of 0 to 5 of increasing severity of IYSV symptoms. The rating was 0 if there were no symptoms, 1 if 1-25 percent of foliage was diseased, 2 if 26-50 percent of foliage was diseased, 3 if 51-75 percent of foliage was diseased, 4 if 76-99 percent of foliage was diseased, and 5 if 100 percent of foliage was diseased. At harvest, bulbs from one of the border rows in each plot of both trials were rated for single centers. Twenty-five consecutive onions ranging in diameter from 3½ to 4¼ inches were rated. The onions were cut equatorially through the bulb middle and separated into single-centered and multiple-centered bulbs. The multiple-centered bulbs had the long axis of the inside diameter of the first single ring measured. These multiple-centered onions were ranked according to the diameter of the first single ring: small had diameters less than 1½ inches, medium had diameters from 1½ to 2¼ inches, and large had diameters greater than 2¼ inches. Onions were considered "functionally single centered" for processing if they were single centered or had a small multiple center. Onions from the middle two double rows in each plot in the early maturity trial were topped by hand and bagged on August 20. The onions were graded on August 24. The onions in the full-season trial were lifted on September 12 to field cure. Onions from the middle two rows in each plot of the full-season trial were topped by hand and bagged on


September 21. The bags were put in storage on September 27. Before being placed in storage each bag was weighed. The storage shed was ventilated and the temperature was slowly decreased to maintain air temperature as close to 34°F as possible. Onions from the full-season trial were graded out of storage on January 8 and 9, 2013. During grading, bulbs were separated according to quality: bulbs without blemishes (No. 1s), split bulbs (No. 2s), neck rot (bulbs infected with the fungus Botrytis allii in the neck or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold (bulbs infected with the fungus Aspergillus niger). The No. 1 bulbs were graded according to diameter: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches). Bulb counts per 50 lb of supercolossal onions were determined for each plot of every variety by weighing and counting all supercolossal bulbs during grading. Marketable yield consists of No.1 bulbs larger than 2¼ inches. After grading, two replicates of each variety were evaluated for subjective quality characteristics on January 11, 2013 (Fig. 1, Table 1). The quality characteristics were evaluated by a consensus of 15-20 people without knowing the variety identities. Evaluators included Oregon State University and seed company employees. The characteristics evaluated were: bulb shape, skin color, bulb shape uniformity, firmness, skin retention, and flesh brightness. Varietal differences were compared using analysis of variance. Means separation was determined using Fisher’s least significant difference test at the 5 percent probability level, LSD (0.05). The varieties from each of the early maturity and full-season trials were compared for yield, grade, internal quality, and disease expression. The least significant difference LSD (0.05) values in each table should be considered when comparisons are made between varieties for significant differences in performance characteristics. Differences between varieties equal to or greater than the LSD value for a characteristic should exist before any variety is considered different from any other variety in that characteristic. Variety performance will vary by year. Growers are encouraged to review performance over a number of years before choosing a variety to plant. Results The rate of accumulation of growing degree-days (50-86°F) in 2012 was close to the 22-year average (Fig. 1). The soil water tension at 8-inch depth was substantially drier than the ideal of 25 cb several times, reaching above 40 cb three times (Fig. 2). One episode of soil water tension reaching 60 cb at the 8-leaf stage (late June/early July) can reduce marketable onion yield (Shock et al. 2006). Drier than ideal soil was caused by delayed irrigations during hand weeding operations. During July, irrigations were required every 3 to 4 days to maintain the soil water tension below 25 cb. The application of herbicide on June 1 (Goal® at 0.19 lb ai/acre, Buctril® at 0.32 lb ai/acre, and Select® at 0.19 lb ai/acre) resulted in visible injury, observed as prostrate and twisted foliage. This higher than normal herbicide injury could have been caused by the application of insecticide with a spreader/penetrant adjuvant the previous day. The adjuvant could have weakened the waxy leaf cuticle that protects the onion foliage from herbicide damage. In 2012, the IYSV pressure was low and did not vary by variety (data not shown). The varieties differed substantially in the number of thrips per plant and thrips damage (Table 3).


Early Maturing Trial The percentage of single-centered bulbs averaged 46.8 percent and ranged from 33.6 percent for ‘Spanish Medallion’ to 60 percent for ‘Montero’ (Table 1). Functionally single-centered onions averaged 94 percent and ranged from 88 percent for Spanish Medallion to 100 percent for Montero. Total yield averaged 859 cwt/acre and ranged from 759.2 cwt/acre for Montero to 958 cwt/acre for Spanish Medallion (Table 2).

Full-season Trial ‘Joaquin’, ‘Cometa’, ‘Granero’, and ‘Scout’ were among the varieties with the lowest herbicide injury ratings from herbicide application on June 1 (Table 3). ‘Advantage’, ‘Oracle’, ‘Morpheus’, ‘Avalon’, ‘Maverick’, Joaquin, and DPLD 1476 were among the varieties with the lowest thrip leaf damage ratings. In comparing varieties for herbicide injury and thrips damage, varieties with lower herbicide injury (Fig. 3) or lower thrips damage (Fig. 4) tended to have higher marketable yield. The percentage of single-centered bulbs averaged 50 percent and ranged from 0 percent for ‘Rio Rojo’ to 88 percent for ‘Annilo’ (Table 4). The percentage of functionally single-centered bulbs averaged 54.9 percent and ranged from 4.1 percent for Rio Rojo to 92 percent for Annilo. The herbicide damage may have reduced the single centers observed in the 2012 onion variety trial (Fig. 5). Marketable yield averaged 702 cwt/acre and ranged from 8.4 cwt/acre for Rio Rojo to 1,115 cwt/acre for Avalon (Table 5). Avalon had the highest marketable yield followed by ‘Ranchero’, Maverick, Oracle, Scout, Joaquin, ‘Ruffian’, and Advantage.

Subjective Quality Evaluation Subjective quality ratings can be found in Table 7 and explanation of the bulb shape rating system can be found in Figure 6 and Table 6. Significant variation was found between varieties in all subjective characteristics except flesh brightness.

Acknowledgements This project was funded by the Idaho-Eastern Oregon Onion Committee, cooperating onion seed companies, and Oregon State University. References Shock, C.C., R. Flock, E. Feibert, C.A. Shock, A. Pereira, and L. Jensen. 2005. Irrigation monitoring

using soil water tension. Oregon State University Extension Service EM 8900. Shock, C.C., E. Feibert, and L.D. Saunders. 2006. Short-duration water stress decreases onion single

centers without causing translucent scale. Oregon State University Agricultural Experiment Station Special Report 1070, pages 80–89.

Shock, C.C., E. Feibert, L. Jensen, and J. Klauzer. 2010. Successful onion irrigation scheduling, Sustainable Agriculture Techniques. Oregon State University Extension Service. SR 1097.


Figure 1. Cumulative growing degree-days (50-86°F) over time for years with lowest (1993) and highest (2003) totals since 1990, compared to 2012 and to the 22-year average (1990-2011), Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 2. Soil water tension at 8-inch depth over time for onions furrow irrigated at 25 cb, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. The soil became substantially drier than the ideal range.


Table 1. Maturity and single- and multiple-center bulb ratings for early maturing onion varieties, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Maturity Aug. 15 Multiple center Single center Seed company

Variety Bulb color

Tops down

Leaf dryness

large medium small functional* single

----------------------------------------------- % ------------------------------------------------ Nunhems Montero Y 52.0 30.0 0.0 0.0 40.0 100.0 60.0 Sakata Spanish Medallion Y 42.0 20.0 4.0 8.0 54.4 88.0 33.6 Average 47.0 25.0 2.0 4.0 47.2 94.0 46.8 LSD (0.05) NS NS NS 6.1 NS 7.0 15.9 *single + small double

Table 2. Yield and grade performance of early maturing onion varieties lifted and harvested August 20, 2012, Malheur Experiment Station, Oregon State University, Ontario, OR.

Marketable yield by grade Bulb counts >4¼ in

Seed company

Variety Bulb color

Total yield Total >4¼ in 4-4¼ in 3-4 in 2¼-3 in No. 2s Small

------------------------------------------ cwt/acre ------------------------------------ #/50 lb Nunhems Montero Y 759.2 744 0 10.4 627.2 106.5 0 15.2

Sakata Spanish Medallion Y 958 944.6 3.3 101.5 770.4 69.4 0 13.3 31.5 Average 858.6 844.3 1.6 55.9 698.8 87.9 0 14.3 31.5 LSD (0.05) 115 110.3 NS 77.1 55.1 NS NS NS NS


Table 3. Maturity, subjective herbicide injury, thrips counts, and subjective thrips damage of full-season experimental and commercial onion varieties, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Herbicide and thrips injury: 0 = no injury, 10 = highest injury.

Bulb color

Maturity Aug. 15 Herbicide injury

Thrips counts Thrips leaf damage Seed company Variety Tops

down Leaf

dryness 6 Jun 28 Jun

---------- % ---------- 0-10 --- No./plant --- 0-10 A. Takii Centerstone Y 12 28 6.0 6.5 11.0 6.6

TTA-747 Y 8 8 4.6 8.3 10.9 5.2 Bejo Calibra Y 32 28 6.6 8.7 5.5 6.6

Crockett Y 10 18 4.8 9.5 10.3 6.4

Delgado Y 18 16 6.2 5.8 7.7 5.8

Legend Y 10 12 5.0 6.5 8.0 5.8

Sedona Y 10 14 5.0 11.0 10.7 6.2

Hamilton Y 6 14 5.6 8.5 18.9 5.6 Crookham Red Beret R 26 36 6.2 9.6 12.1 7.6

Oracle Y 12 6 5.4 4.0 4.1 3.2

Advantage Y 10 10 7.0 3.8 5.0 3.0

Avalon Y 22 12 5.0 5.6 7.1 3.8

Pontiac Y 16 26 6.0 4.5 12.2 7.4

Trigger Y 4 8 5.6 3.4 4.5 4.2

Scout Y 22 14 3.0 7.1 8.3 5.6

Morpheus Y 14 6 4.6 4.0 5.8 3.6

Esteem Y 10 20 5.6 5.5 6.5 7.2 Nickerson-Zwaan NIZ 37-81 Y 14 18 3.4 5.1 8.3 5.4

NIZ 37-85 Y 20 16 4.2 8.6 6.1 6.4

Cruiser Y 14 20 5.6 7.5 8.0 6.4

Frontino Y 9 9 6.8 5.1 7.4 4.8

Maverick Y 10 10 3.6 6.0 6.3 4.0

Outlaw Y 26 24 4.0 7.6 7.9 6.8

Ventura Y 36 30 3.8 8.8 10.1 7.4 Nippon Norin NN65 Y 8 12 4.6 9.9 10.1 5.0

Nunhems Ranchero Y 14 12 5.0 6.8 7.5 4.8

Granero Y 10 14 2.8 5.5 7.7 5.2

Vaquero Y 10 14 4.6 7.1 8.8 5.6

Arcero Y 10 14 3.4 5.5 6.1 5.6

Joaquin Y 8 6 2.0 5.4 8.1 4.0

Pandero Y 8 10 5.6 5.8 5.7 4.2

Annilo Y 14 14 3.4 7.9 8.7 5.6

Cometa W 6 6 2.2 6.9 13.4 4.2

Marenge R 40 40 5.8 8.6 11.2 7.2 Sakata XON-659Y Y 22 8 5.4 5.0 5.9 4.6 Seminis Barbaro Y 12 14 3.6 6.9 6.4 5.0

Belmar Y 14 18 5.0 5.4 7.6 6.0

Ruffian Y 12 10 3.6 6.1 7.0 5.2

Swale Y 16 12 4.0 7.0 9.8 4.8 D. Palmer DPID 1472 Y 20 22 4.8 3.8 8.1 6.0

DPL 1473 Y 10 24 5.8 4.3 10.8 5.4

DPLD 1476 Y 10 10 7.0 5.3 6.2 4.0

DPLD 1477 Y 16 24 7.2 7.2 9.6 6.8

DPR 3071 R 10 22 8.6 4.7 8.5 7.2

DPR 3072 R 12 26 7.6 7.9 10.8 6.4

DPR 3073 R 16 28 7.4 6.0 12.3 6.6

Rio Rojo R 92 52 4.0 4.0 2.9 na

DPLD 2056 W 6 12 5.0 5.2 6.9 4.4

DPLD 2057 W 16 20 7.4 4.5 4.9 5.6

Average

16.0 17.3 5.1 6.4 8.3 5.5

LSD (0.05) 8.4 7.5 0.9 3.2 3.4 1.1


Figure 3. Relationship between severity of thrips leaf damage and marketable yield. Each data point represents one onion variety (average of 5 replicates). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 4. Relationship between severity of herbicide injury from the Goal, Buctril, and Select application on June 1 and marketable yield. Each data point represents one variety (average of 5 replicates). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 5. Relationship between severity of herbicide injury from the Goal, Buctril, and Select application on June 1 and the percentage of single-centered onion bulbs. Each data point represents one variety (average of 5 replicates). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Table 4. Single- and mutiple-centered bulb rating for full-season onion varieties, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Bulb color

Multiple center Single center Seed company Variety large medium small functional single centera single center

--------------------------------------- % ------------------------------------ A. Takii Centerstone Y 20.8 45.6 2.4 33.6 31.2

TTA-747 Y 17.6 48.8 2.4 33.6 31.2 Bejo Calibra Y 30.3 52.1 5.6 17.6 12.0

Crockett Y 9.6 40.0 3.2 50.4 47.2 Delgado Y 21.6 48.8 4.0 29.6 25.6 Legend Y 31.2 55.2 4.0 13.6 9.6 Sedona Y 16.8 35.2 3.2 48.0 44.8 Hamilton Y 17.6 37.6 5.6 44.8 39.2

Crookham Red Beret R 5.6 15.2 4.0 79.2 75.2 Oracle Y 6.4 21.6 0.0 72.0 72.0 Advantage Y 6.4 26.3 0.8 67.3 66.6 Avalon Y 19.2 40.8 2.4 40.0 37.6 Pontiac Y 6.4 20.0 4.8 73.6 68.8 Trigger Y 4.0 11.2 4.0 84.8 80.8 Scout Y 12.8 41.6 3.2 45.6 42.4 Morpheus Y 4.0 9.6 8.8 86.4 77.6 Esteem Y 0.8 19.2 1.6 80.0 78.4

Nickerson-Zwaan NIZ 37-81 Y 4.8 18.5 0.8 76.7 75.9 NIZ 37-85 Y 8.0 26.2 3.2 65.8 62.6 Cruiser Y 11.0 48.4 4.8 40.5 35.8 Frontino Y 3.2 14.4 3.2 82.4 79.2 Maverick Y 13.3 49.5 5.4 37.2 31.8 Outlaw Y 11.2 31.2 16.8 57.6 40.8 Ventura Y 6.4 27.2 12.0 66.4 54.4

Nippon Norin NN65 Y 1.6 21.6 17.6 76.8 59.2 Nunhems Ranchero Y 4.0 29.9 5.7 66.1 60.4

Granero Y 4.0 32.0 2.4 64.0 61.6 Vaquero Y 10.4 34.4 2.4 55.2 52.8 Arcero Y 2.4 9.6 2.4 88.0 85.6 Joaquin Y 0.0 22.4 4.0 77.6 73.6 Pandero Y 11.2 37.6 0.8 51.2 50.4 Annilo Y 0.8 7.2 4.0 92.0 88.0 Cometa W 0.8 18.4 4.8 80.8 76.0 Marenge R 5.6 19.2 5.6 75.2 69.6

Sakata XON-659Y Y 12.0 35.2 3.2 52.8 49.6 Seminis Barbaro Y 4.8 17.6 4.8 77.6 72.8

Belmar Y 8.0 24.0 3.2 68.0 64.8 Ruffian Y 8.0 28.0 0.8 64.0 63.2 Swale Y 4.0 28.0 1.6 68.0 66.4

D. Palmer DPID 1472 Y 24.8 34.4 2.4 40.8 38.4 DPL 1473 Y 32.8 48.0 2.4 19.2 16.8 DPLD 1476 Y 58.4 24.0 12.8 17.6 4.8 DPLD 1477 Y 27.2 32.8 13.6 40.0 26.4 DPR 3071 R 19.2 31.2 4.0 49.6 45.6 DPR 3072 R 28.8 32.8 6.4 38.4 32.0 DPR 3073 R 40.0 43.2 4.8 16.8 12.0 Rio Rojo R 87.9 8.0 4.1 4.1 0.0 DPLD 2056 W 40.0 31.2 3.2 28.8 25.6 DPLD 2057 W 17.6 33.6 16.0 48.8 32.8 Average 15.2 30.0 4.9 54.9 50.0

LSD (0.05) 9.9 16.0 9.4 15.6 14.1 asingle + small double


Table 5. Yield and grade of full-season experimental and commercial onion varieties graded out of storage in January 2013, Malheur Experiment Station, Oregon State University, Ontario, OR. Continued on next page. Marketable yield by grade Bulb

counts >4¼ in

Seed company Variety Bulb color

Total yield Total >4¼ in 4-4¼ in 3-4 in 2¼-3 in

No. 2s Small

Total rot

Neck rot

Plate rot

Black mold

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

A. Takii Centerstone Y 636.0 618.0 0.0 8.7 537.5 71.9 3.6 11.8 0.4 0.0 0.4 0.0 TTA-747 Y 861.8 837.1 5.6 168.9 637.1 25.5 1.7 7.9 1.6 1.4 0.2 0.0 37.0

Bejo Calibra Y 657.7 636.7 0.0 13.8 582.2 40.7 10.2 8.2 0.4 0.2 0.1 0.0

Crockett Y 603.2 582.8 0.0 7.0 514.7 61.1 4.8 14.8 0.1 0.1 0.1 0.0

Delgado Y 698.1 671.7 0.0 32.7 600.3 38.6 16.3 6.9 0.5 0.3 0.2 0.0

Legend Y 671.5 640.7 0.0 29.5 560.8 50.4 10.8 8.8 1.8 1.2 0.5 0.0

Sedona Y 740.9 719.9 0.0 41.5 621.2 57.2 2.8 14.2 0.5 0.4 0.1 0.0 Hamilton Y 715.4 700.7 1.7 29.3 625.3 44.4 2.5 11.3 0.1 0.0 0.1 0.0 30.1

Crookham Red Beret R 534.2 511.3 0.0 4.4 365.8 141.1 2.3 18.4 0.4 0.3 0.1 0.0

Oracle Y 958.2 940.1 0.0 350.7 574.8 14.5 1.0 7.0 1.1 1.0 0.0 0.1

Advantage Y 951.1 908.7 24.6 308.4 511.9 63.8 1.2 9.9 3.1 3.0 0.0 0.0 33.5

Avalon Y 1143.3 1114.5 76.7 512.8 500.1 24.9 2.2 9.9 1.4 1.1 0.2 0.2 32.1

Pontiac Y 525.8 507.6 0.0 7.7 391.4 108.5 0.9 15.7 0.3 0.1 0.1 0.0

Trigger Y 758.9 749.9 14.1 152.1 556.1 27.6 0.0 5.8 0.4 0.4 0.0 0.0 36.6

Scout Y 1000.2 940.0 38.5 355.8 503.8 42.0 1.4 7.1 4.6 2.8 0.5 1.3 31.1

Morpheus Y 890.5 863.7 16.1 271.5 535.4 40.7 0.9 8.6 1.9 1.7 0.1 0.0 32.8

Esteem Y 729.2 712.9 1.7 45.0 626.2 40.1 0.0 10.8 0.7 0.1 0.6 0.0 31.3 Nickerson-Zwaan NIZ 37-81 Y 711.4 696.6 4.4 160.3 498.2 33.6 0.0 11.1 0.5 0.2 0.3 0.0 35.6

NIZ 37-85 Y 756.2 742.0 3.4 124.4 587.9 26.3 3.6 9.6 0.1 0.0 0.1 0.0 30.7

Cruiser Y 609.2 600.0 0.0 24.1 523.8 52.1 0.8 6.9 0.2 0.0 0.2 0.0

Frontino Y 784.5 769.3 0.0 167.2 577.8 24.3 2.4 6.5 0.8 0.3 0.4 0.0

Maverick Y 977.1 953.5 12.3 350.0 567.8 23.4 4.4 9.0 1.1 0.6 0.5 0.0 33.8

Outlaw Y 660.1 642.8 0.0 31.7 561.2 49.8 4.5 11.2 0.2 0.0 0.2 0.0

Ventura Y 592.8 571.0 1.5 21.9 458.2 89.3 2.9 18.7 0.0 0.0 0.0 0.0 33.3 Nippon Norin NN65 Y 739.5 718.8 0.0 97.8 560.6 60.4 0.0 15.5 0.7 0.2 0.5 0.0

Table 5. Yield and grade out of storage January 2013. Continued. Marketable yield by grade

Bulb counts >4¼ in

Seed company

Variety Bulb color

Total yield Total >4¼ in 4-4¼ in 3-4 in 2¼-3 in

No. 2s Small

Total rot

Neck rot

Plate rot

Black mold

-------------------------------------- cwt/acre -------------------------------------- --------- % of total yield --------- #/50 lb Nunhems Ranchero Y 996.8 972.7 54.7 339.8 547.5 30.8 4.3 9.2 1.1 0.9 0.2 0.0 33.9

Granero Y 841.5 823.9 0.0 148.3 652.9 22.7 2.5 11.0 0.5 0.4 0.1 0.0

Vaquero Y 916.6 899.1 15.9 272.2 594.3 16.6 1.4 5.0 1.2 0.9 0.1 0.2 34.9

Arcero Y 882.8 866.1 0.0 196.9 646.0 23.2 0.0 9.3 0.9 0.5 0.3 0.0

Joaquin Y 945.5 927.9 32.7 439.7 437.5 18.0 0.0 9.4 0.8 0.3 0.5 0.0 36.3

Pandero Y 848.1 829.2 3.3 237.7 548.1 40.1 3.8 11.8 0.5 0.0 0.5 0.0 31.3

Annilo Y 865.3 845.2 1.9 122.1 690.6 30.5 0.0 8.5 1.3 0.5 0.8 0.0 27.2

Cometa W 893.3 861.6 2.4 181.1 648.9 29.2 0.0 13.0 2.1 1.6 0.5 0.0 32.5

Marenge R 451.2 420.5 0.0 0.0 316.1 104.4 1.7 26.6 0.5 0.3 0.2 0.0 Sakata XON-659Y Y 871.2 862.4 9.1 315.0 515.8 22.6 2.9 4.3 0.2 0.2 0.0 0.0 33.2 Seminis Barbaro Y 864.1 847.2 19.8 251.5 550.2 25.7 2.4 10.5 0.5 0.2 0.3 0.0 36.5

Belmar Y 763.5 744.6 0.0 93.3 611.5 39.9 0.0 13.5 0.7 0.5 0.2 0.0

Ruffian Y 930.5 909.7 47.8 349.7 481.8 30.4 3.1 11.8 0.7 0.4 0.1 0.2 34.0 Swale Y 872.8 857.7 10.6 232.9 583.0 31.2 0.0 7.8 0.9 0.4 0.5 0.0 32.6

D. Palmer DPID 1472 Y 644.5 593.6 0.0 81.3 462.5 49.7 31.9 13.5 0.8 0.1 0.6 0.0

DPL 1473 Y 609.3 567.6 0.0 5.0 472.2 90.5 22.4 18.0 0.2 0.0 0.2 0.0

DPLD 1476 Y 753.2 564.8 2.8 68.8 452.7 40.5 172.8 15.0 0.1 0.0 0.1 0.0 37.0

DPLD 1477 Y 461.7 411.2 0.0 0.0 264.2 147.0 20.1 23.4 1.6 0.5 1.1 0.0

DPR 3071 R 408.7 349.4 0.0 0.0 181.4 168.0 20.3 38.0 0.2 0.2 0.0 0.0

DPR 3072 R 378.9 296.9 0.0 2.2 139.4 155.3 35.7 41.9 1.1 0.1 0.1 0.9

DPR 3073 R 362.9 265.5 0.0 0.0 134.4 131.1 46.6 47.1 1.0 0.0 0.0 1.0

Rio Rojo R 176.5 8.4 0.0 0.0 1.9 6.5 9.9 13.2 84.8 10.1 0.1 74.6a

DPLD 2056 W 846.5 730.2 6.7 128.1 554.0 41.4 69.2 15.2 3.8 2.0 1.8 0.0 30.8 DPLD 2057 W 613.6 577.2 0.0 5.0 490.6 81.6 9.8 18.3 1.4 1.1 0.3 0.0

average

736.8 701.7 8.3 138.5 501.2 53.7 11.1 13.5 2.6 0.7 0.3 1.6 33.2

LSD (0.05) 112.6 110.3 21.8 86.7 113.4 33.8 13.2 11.0 5.4 3.1 0.6 7.5 2.5 amany types of decomposition were present on these bulbs.

Figure 6. Onion bulb shape rating system. Malheur Experiment Station, Oregon State University, Ontario, OR. Table 6. Onion variety subjective quality evaluation rating system.

Characteristic Scale Description Bulb shape A-H see Fig. 6 Skin colora 1-5 1 = light, 5 = dark Bulb shape uniformity 1-5 1 = disuniform shape, 5 = uniform shape Firmness 1-5 1 = soft, 5 = hard Skin retention 1-5 1 = bald, 5 = no cracks Flesh brightness 1-5 yellow varieties: 1 = yellow, 5 = white

red varieties: 1 = dark red, 5 = pale red white varieties: 1 = less white, 5 = very white

aYellow varieties varied from light yellow to yellow-brown. Red varieties varied from pale red to intense red. White varieties varied from off-white to intense white.


Table 7. Onion variety subjective quality evaluation on January 11, 2013, Malheur Experiment Station, Oregon State University, Ontario, OR.

Bulb shapea

Skin colorb

Bulb shape uniformityb Scale

retentionb Flesh

brightnessb Company Variety Color Firmnessb

----------------------------------------- 1-5 ------------------------------------- A. Takii Centerstone Y c 3.0 3.5 3.0 2.5 2.5

TTA-747 Y d 5.0 3.5 3.0 4.0 3.0 Bejo Calibra Y d 6.0 3.5 3.0 4.0 3.0

Crockett Y d 6.0 4.0 4.0 5.0 3.0

Delgado Y e 5.0 4.0 4.0 5.0 2.5

Legend Y d 5.5 4.0 4.0 4.5 2.5

Sedona Y e 4.0 3.0 3.5 4.5 3.0

Hamilton Y e 6.0 3.5 4.0 4.5 2.5 Crookham Red Beret R c 5.5 2.5 3.0 3.0 3.5

Oracle Y f 5.0 3.5 3.0 5.0 3.0

Advantage Y f 4.0 3.5 3.0 4.0 3.0

Avalon Y d 3.5 3.0 2.0 2.5 3.0

Pontiac Y e 5.5 3.0 3.0 4.0 3.0

Trigger Y f 5.0 4.0 3.5 3.5 3.0

Scout Y c 3.0 4.0 2.0 2.5 3.5

Morpheus Y e 4.0 3.5 2.5 4.5 3.5

Esteem Y c 3.5 2.5 2.5 3.0 3.0 Nickerson-Zwaan NIZ 37-81 Y e 4.0 3.5 3.0 4.0 3.0

NIZ 37-85 Y d 5.5 4.0 3.0 3.5 3.0

Cruiser Y e 5.0 3.0 3.0 3.5 2.5

Frontino Y e 5.0 3.5 3.0 4.0 3.0

Maverick Y d 4.5 3.0 3.0 4.0 3.5

Outlaw Y d 5.0 3.0 3.0 3.5 3.0

Ventura Y e 5.5 3.0 3.0 4.0 2.5 Nippon Norin NN65 Y f 4.0 4.0 3.0 4.5 3.5

Nunhems Ranchero Y c 4.0 3.5 3.0 3.5 3.0

Granero Y d 6.5 4.0 3.5 5.0 3.0

Vaquero Y d 4.0 3.5 3.0 4.0 3.0

Arcero Y d 5.5 3.5 3.0 5.0 4.0

Joaquin Y e 5.5 3.5 3.0 5.0 3.0

Pandero Y c 5.0 4.0 3.0 4.0 2.0

Annilo Y d 5.5 3.5 4.0 5.0 3.0

Cometa W d 2.0 4.0 3.0 5.0 3.0

Marenge R c 6.5 3.5 2.5 2.0 3.0 Sakata XON-659Y Y c 3.0 4.0 3.0 4.0 3.5 Seminis Barbaro Y e 4.0 3.0 2.0 3.0 2.5

Belmar Y c 5.0 3.5 3.0 3.0 2.5

Ruffian Y c 3.0 3.5 2.0 2.5 3.0

Swale Y c 5.0 4.0 3.0 4.0 3.0 D. Palmer DPID 1472 Y c 3.0 3.5 3.0 3.0 3.0

DPL 1473 Y e 6.0 4.0 4.0 5.0 3.0

DPLD 1476 Y c 6.5 2.0 3.0 5.0 2.0

DPLD 1477 Y d 7.0 2.5 4.0 4.5 2.0

DPR 3071 R c,g 8.0 3.0 3.0 4.0 4.0

DPR 3072 R c 8.0 4.0 3.0 4.0 4.0

DPR 3073 R c 7.5 3.5 3.5 3.0 3.5

Rio Rojo R na 7.0 na na na na

DPLD 2056 W d 3.5 3.0 4.5 3.0

DPLD 2057 W d 3.0 2.5 3.0 3.5 2.5

Average d 5.0 3.4 3.1 3.9 3.0 LSD (0.05) 1.2 1.1 0.6 0.8 NS

aBulb shape: see Figure 6. bSubjective ratings are described in Table 6. na: not available due to excessive decomposition.


ONION PRODUCTION FROM TRANSPLANTS AND SETS Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Bob Simerly, McCain Foods, Fruitland, ID Introduction Increased interest in an earlier start for onion harvest has led to interest in transplanting onions. Our earlier research showed that when onions are grown from transplants they can be harvested in July (Shock et al. 2004, 2007, 2008, 2009, 2010, 2011). This trial evaluated the performance of six onion varieties grown from transplants produced in a greenhouse at the Malheur Experiment Station, in Ontario, Oregon. Materials and Methods Onions were grown in 2012 on an Owyhee silt loam with a pH of 7.7 and 1.7 percent organic matter, previously planted to wheat. In the fall of 2011, the wheat stubble was shredded and the field was irrigated. The field was then disked, moldboard plowed, and groundhogged. Based on a soil analysis, 100 lb of phosphorus/acre, 200 lbs of sulfur/acre, 1,000 lbs of gypsum/acre, and 1 lb of boron/acre were broadcast before plowing. On September 25, the field was fumigated with Vapam® at 15 gal/acre and bedded at 22 inches.

Transplants of six onion varieties were grown in a heated greenhouse (65°F day, 45°F night air temperatures) at Ontario, Oregon. Onion seed was planted in the greenhouse in flats with a vacuum seeder at 72 seeds/flat on January 27, 2012. The seed was sown on a 1-inch layer of Sunshine general purpose potting mix. The seed was then covered with 1 inch of potting mix. The flats were watered immediately after planting and were kept moist. Onion seedlings began emerging on February 6. Transplants were grown without supplemental light.

The field had drip tape laid at 4-inch depth between 2 onion beds before planting. The drip tape had emitters spaced 12 inches apart and emitter flow rate of 0.22 gal/min/100 ft (Toro Aqua-Traxx, Toro Co., El Cajon, CA). The distance between the tape and the center of each double row of onions was 11 inches.

The seedlings were transplanted on March 23. The seedlings were planted in 2 rows spaced 3 inches apart on the 22-inch beds. The spacing between plants in each row was 6 inches (every 3 inches in the double row), equivalent to 95,000 plants/acre. Plots of each variety were 20 ft long by 4 double rows wide arranged in a randomized complete block design with 5 replicates.

An observation trial of onion bulbs grown from sets with one plot of each of 7 varieties was planted on March 23. The sets were grown in a farm near Ontario, Oregon. The sets of each

Onion Production from Transplants and Sets 26

variety were planted manually in double rows spaced 3 inches apart on 22-inch beds. The sets were approximately 0.4 to 0.7 inches in diameter and were planted in double rows at 2 sets/ft of single row (6-inch spacing between individual onion plants or 95,000 plants/acre). Plots of each variety were 20 ft long by 4 double rows wide.

The onions were managed to avoid yield reductions from weeds, pests, diseases, water stress, and nutrient deficiencies. Poast® at 2 pt/acre was broadcast on April 3. Prowl® H2O at 2 pt/acre was broadcast for weed control on April 25. Root tissue samples were taken on June 18, July 2, and July 18. Based on the tissue analyses, a total of 135 lb nitrogen/acre, 5 lb magnesium/acre, 5 lb calcium/acre, and 0.6 lb boron/acre were applied during the season. The nutrients were injected through the drip tape.

The field was irrigated as necessary to maintain soil water tension at 20 cb at 8-inch depth. Soil water tension was monitored by six granular matrix sensors (Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside, CA) centered at 8-inch depth below the onion row. The sensors were automatically read three times a day with an AM-400 meter (Mike Hansen Co., East Wenatchee, WA). The field was irrigated until the last harvest on August 6.

On July 19, bolted onions in each plot were counted. On July 23, July 30, and August 6, 6.7 ft of the middle 2 rows in each plot were topped and bagged. Decomposing bulbs were not bagged. At each harvest, the onions in each plot were visually rated for the percentage of tops that were down and the percent leaf dryness. Following each harvest the onions were graded. Bulbs were separated according to quality: bulbs without blemishes (No. 1s), split bulbs (No. 2s), bulbs infected with neck rot (Botrytis allii) in the neck or side, plate rot (Fusarium oxysporum), or black mold (Aspergillus niger). The No. 1 bulbs were graded according to diameter: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches). Bulb counts per 50 lb of supercolossal onions were determined for each plot of every variety by weighing and counting all supercolossal bulbs during grading.

Onion bulbs from all harvests were rated for single centers. Twenty-five onions ranging in diameter from 3½ to 4¼ inches from each plot were rated. The onions were cut equatorially through the bulb middle and separated into single-centered and multiple-centered bulbs. The multiple-centered bulbs had the the long axis of the inside diameter of the first single ring measured. These multiple-centered onions were ranked according to the diameter of the first single ring: small had diameters under 1½ inch, medium had diameters from 1½ to 2¼ inches, and large had diameters over 2¼ inches. Onions were considered “functionally single centered” for processing if they were single centered or had a small multiple center.

After grading, a sample of approximately 100 No. 1 jumbo bulbs of each early harvest variety was placed in crates and stored in a shed at ambient temperature for 2 weeks. After 2 weeks the samples were evaluated for the number of sprouted or decomposed bulbs.

Variety differences were compared using repeated measures analysis of variance. Means separation was determined using Fisher’s least significant difference test at the 5 percent probability level, LSD (0.05).


Results and Discussion Transplants

July 23 Harvest Marketable yield on July 23 averaged 772 cwt/acre and ranged from 676 cwt/acre for ‘Crocket’ to 815 cwt/acre for 7408. ‘Pulsar’ 7408, and ‘Hendrix’ were among the varieties with the highest marketable yield (Table 1). All varieties had more than 95 percent functionally single-centered bulbs (Table 2). All varieties had more than 10 percent tops down at harvest, except Crocket and ‘Gunnison’ (Table 3). Gunnison had the highest percentage of bolted bulbs (30.9 %), followed by Crocket (17.6 %) and others having significantly less bolting. The lines 7408, Hendrix, and 7406 had the least bolting at 0.8, 0.9, and 2.3 percent, respectively. All varieties had fewer than 10 percent sprouted or decomposed bulbs 2 weeks after harvest (Table 3).

July 30 Harvest Marketable yield on July 30 averaged 844 cwt/acre and ranged from 787 cwt/acre for Crocket to 880 cwt/acre for 7406. Varieties 7406 and 7408 were among those with the highest marketable yield (Table 1). All varieties had more than 90 percent functionally single-centered bulbs (Table 2). All varieties had more than 70 percent tops down except Crocket (12%), and Gunnison (30.9%) (Table 3). All varieties had fewer than 10 percent sprouted or decomposed bulbs 2 weeks after harvest (Table 3).

August 6 Harvest Yield of all varieties increased up to the last harvest. Marketable yield on August 6 averaged 963 cwt/acre and ranged from 933 cwt/acre for Gunnison to 1,000 cwt/acre for Pulsar. Crocket had the highest supercolossal yield (Table 1). All varieties had more than 90 percent functionally single-centered bulbs (Table 2). All varieties had fewer than 10 percent sprouted or decomposed bulbs 2 weeks after harvest (Table 3).

Overall Onion yields varied over time between varieties (p = 0.10) suggesting that the rates of development and maturity differed between varieties. All of the varieties had less than 80 percent bullet single-centered bulbs on all harvest dates. However, all of the varieties had more than 80 percent functionally single-centered bulbs on all harvest dates. All of the varieties showed a decrease in the percentage of single-centered bulbs with the successive harvests.


Sets The plots planted to sets were not replicated so none of the differences observed could be tested for statistical significance. NH 7202/03 had high marketable yield on August 6 (Table 4). For all varieties, total and marketable yield did not increase or increased only slightly from the second (July 30) to the third harvest (August 6,Table 4). By the second harvest (July 30), all varieties had 40 percent or more tops down and 30 percent or more leaf dryness. Bolting was less than 3 percent for all varieties except ‘Talon’ (Table 5), at 14.7 percent bolting. All varieties had fewer than 10 percent sprouted or decomposed bulbs 2 weeks after harvest (Table 5).


Table 1. Yield and grade at three harvest dates for six onion varieties grown from transplants, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Total yield

Marketable yield by grade Bulb counts >4¼ in Company Variety Total

>4¼ in

4-4¼ in 3-4 in

2¼-3 in Small Doubles

------------------------------------ cwt/acre ----------------------------------------- #/50 lb

July 23 harvest Bejo Crocket 681.0 676.0 0.0 97.6 559.4 19.0 5.0

Gunnison 765.0 764.9 0.0 179.2 573.9 11.8 0.1 Nunhems 7406 792.6 789.9 7.3 155.3 623.1 4.2 2.7

24.5

7408 814.9 814.9 0.0 181.3 630.9 2.7 0.0

Hendrix 776.4 776.3 0.0 145.1 629.8 1.4 0.0 Pulsar 808.5 808.2 0.0 162.5 645.1 0.6 0.3

Average 773.1 771.7 1.2 153.5 610.4 6.6 1.4 24.5

July 30 harvest Bejo Crocket 791.1 787.2 4.8 165.1 605.2 12.0 4.6

36.8

Gunnison 831.0 828.2 0.0 235.9 583.7 8.6 2.8 Nunhems 7406 882.6 880.1 0.0 252.3 614.4 13.4 2.5

7408 878.5 875.8 4.8 225.5 640.6 4.8 2.7

36.8

Hendrix 844.3 841.1 0.0 167.2 662.0 11.9 3.1

Pulsar 853.7 853.0 0.0 247.4 603.7 1.9 0.8 Average 846.9 844.2 1.6 215.6 618.3 8.8 2.7 36.8

August 6 harvest Bejo Crocket 970.6 966.0 83.5 450.3 422.5 9.8 4.6 2.6 34.8 Gunnison 936.9 932.7 34.7 376.2 515.7 6.1 4.1 0.0 30.9 Nunhems 7406 978.7 976.6 16.9 443.7 509.5 6.5 2.1 0.0 31.9

7408 967.5 963.2 21.5 411.3 527.3 3.1 4.3 0.0 34.9

Hendrix 940.9 937.4 17.6 314.9 595.3 9.6 3.5 0.0 31.4

Pulsar 1003.5 999.7 29.9 515.5 440.2 14.1 3.8 0.0 32.8

Average 966.3 962.6 34.0 418.6 501.8 8.2 3.7 0.4 32.8

Average over harvest dates Bejo Crocket 814.2 809.7 29.5 237.6 529.0 13.6 4.7 1.8 35.1 Gunnison 844.3 842.0 11.6 263.7 557.8 8.9 2.3 0.0 30.9 Nunhems 7406 884.7 882.2 8.1 283.8 582.3 8.1 2.5 0.0 29.5

7408 887.0 884.7 8.8 272.7 599.6 3.6 2.3 0.0 35.5

Hendrix 853.8 851.6 5.9 209.1 629.0 7.6 2.2 0.0 31.4

Pulsar 888.6 886.9 10.0 308.4 563.0 5.5 1.6 0.0 32.8 LSD (0.05) Variety NS NS 13.6* NS 62.1 5.7 NS NS NS LSD (0.05) Date 23.3 23.5 9.9 38.8 33.0 NS NS NS NS LSD (0.05) Variety X Date 47.6* 48.0* 24.2 NS NS 9.1 NS NS NS

*LSD (0.10)


Table 2. Bulb single and multiple centers for three harvest dates for six onion varieties grown from transplants, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Multiple center Single center Company Variety Large Medium Small

Functionala Single

------------------------------- % ---------------------------------

July 23 Bejo Crocket 0.0 0.8 28.0

99.2 71.2

Gunnison 0.8 0.8 43.2 98.4 55.2 Nunhems 7406 0.8 0.8 48.8

98.4 49.6

7408 0.8 2.4 41.6

96.8 55.2

Hendrix 0.0 4.0 48.8

96.0 47.2

Pulsar 0.0 0.0 32.8

100.0 67.2

Average 0.4 1.8 43.0 97.8 54.8


99.2 63.2


96.8 29.6

7408 0.8 4.8 52.8

94.4 41.6

Hendrix 0.8 7.1 48.4

92.1 43.7

Pulsar 0.8 1.6 52.8

97.6 44.8

Average 0.8 3.3 50.7 95.9 45.2

August 6 Bejo Crocket 0.0 2.4 40.8

97.6 56.8


92.0 28.0

7408 0.0 4.1 63.3

95.9 32.7

Hendrix 1.6 10.4 46.0

88.0 42.0

Pulsar 0.8 3.9 58.1

95.3 37.2

Average 0.5 5.1 56.1 94.4 38.3

Average over dates Bejo Crocket 0.3 1.1 34.9

98.7 63.7


95.7 35.7

7408 0.5 3.8 52.6

95.7 43.2

Hendrix 0.8 7.2 47.7

92.0 44.3

Pulsar 0.5 1.8 47.9 97.6 49.7 LSD (0.05) Variety NS 2.3 9.6

2.9 10.2

LSD (0.05) Date NS NS 7.2

NS 7.0 LSD (0.05) Variety X Date NS NS NS NS NS

a single center plus small multiple center.


Table 3. Bolting and maturity at harvest, and bulb quality 2 weeks after harvest for six onion varieties grown from transplants harvested on three dates, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Maturity at harvest Bulb quality 2 weeks after harvest

Tops down

Leaf dryness

Sprouted

and decomposed

Total sprouted or

decomposed Company Variety Bolting Sprouted Decomposed

----------------------------------------------------- % ---------------------------------------------------------


2.5 0.8 0.0 3.4

Gunnison 30.9 4.0 10.0 0.0 0.0 0.0 0.0 Nunhems 7406 2.3 26.0 14.0

0.0 0.0 0.0 0.0

7408 0.8 78.0 14.0

0.0 0.7 0.0 0.7

Hendrix 0.9 58.0 10.0

0.0 0.0 0.0 0.0

Pulsar 5.1 64.0 8.0 0.0 0.0 0.0 0.0

Average 9.6 38.3 9.3 0.4 0.3 0.0 0.7

July 30 Bejo Crocket

12.0 10.0

0.8 4.0 0.0 4.8

Gunnison 30.0 16.0 0.0 0.0 0.0 0.0 Nunhems 7406

78.0 28.0

0.0 0.0 0.0 0.0

7408

90.0 26.0

0.7 0.0 0.0 0.7

Hendrix

88.0 30.0

0.0 0.0 0.0 0.0

Pulsar

88.0 20.0 0.0 0.0 0.0 0.0

Average 64.3 21.7 0.3 0.7 0.0 0.9

August 6 Bejo Crocket

24.0 18.0

0.0 6.0 0.0 6.0


92.0 50.0

0.0 0.5 0.0 0.5

7408

98.0 42.0

0.0 0.0 0.0 0.0

Hendrix

100.0 48.0

0.0 0.6 0.0 0.6

Pulsar

92.0 38.0 0.0 1.2 0.0 1.2

Average 75.3 38.7 0.0 2.0 0.0 2.0

Average over dates Bejo Crocket

12.0 9.3

1.1 3.6 0.0 4.7


65.3 30.7

0.0 0.2 0.0 0.2

7408

88.7 27.3

0.2 0.2 0.0 0.5

Hendrix

82.0 29.3

0.0 0.2 0.0 0.2

Pulsar 81.3 22.0 0.0 0.4 0.0 0.4 LSD (0.05) Variety 2.5 7.6 3.1

na na na na

LSD (0.05) Date

4.0 1.8

na na na na LSD (0.05) Var. X Date

9.8 6.3 na na na na


Table 4. Yield and grade at three harvest dates for seven onion varieties grown from sets, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Total yield

Marketable yield by grade Bulb counts >4¼

in Company Variety Total >4¼ in 4-4¼ in 3-4 in 2¼-3 in Small

---------------------------- cwt/acre ---------------------------------

#/50 lb

July 23

Nunhems Arcero 405.9 402.0 0.0 0.0 321.1 80.9 3.9

Sabroso 398.6 377.1 0.0 0.0 254.5 122.6 21.4

Pulsar 562.6 562.4 0.0 0.0 519.3 43.1 0.2

NH 7202/03 447.3 438.0 0.0 0.0 421.3 16.8 9.3

NH7203/02 459.9 455.3 0.0 0.0 356.6 98.7 4.6 Gunnison 405.6 342.5 0.0 0.0 273.0 69.5 46.0

Bejo Talon 408.8 377.4 0.0 10.0 267.3 100.2 5.3 Average 441.3 422.1 0.0 1.4 344.7 76.0 13.0

July 30

Nunhems Arcero 509.3 416.6 0.0 20.0 367.5 29.2 18.5

Sabroso 527.8 513.9 0.0 0.0 435.5 78.4 13.9

Pulsar 598.8 573.5 0.0 59.5 468.7 45.3 16.0

NH 7202/03 629.8 599.5 0.0 149.3 425.9 24.2 10.0

NH7203/02 596.3 571.7 0.0 0.0 500.0 71.6 24.6 Gunnison 546.4 489.7 0.0 44.6 348.6 96.6 22.1

Bejo Talon 428.8 377.8 0.0 0.0 300.8 77.0 18.2 Average 548.2 506.1 0.0 39.1 406.7 60.3 17.6

August 6

Nunhems Arcero 496.8 296.5 0.0 0.0 261.7 34.8 7.4

Sabroso 450.2 420.9 0.0 0.0 342.7 78.2 23.1

Pulsar 546.7 388.8 0.0 13.9 342.5 32.4 10.0

NH 7202/03 670.8 665.1 0.0 173.0 444.8 47.3 5.6

NH7203/02 541.0 448.3 0.0 85.5 308.3 54.5 25.3 Gunnison 608.2 564.3 31.0 74.3 345.5 113.4 23.6 29.8

Bejo Talon 452.0 414.5 0.0 0.0 341.6 72.9 37.5 Average 537.9 456.9 4.4 49.5 341.0 61.9 18.9 29.8

Average over dates

Nunhems Arcero 470.7 371.7 0.0 6.7 316.8 48.3 10.0

Sabroso 458.9 437.3 0.0 0.0 344.2 93.1 19.5

Pulsar 569.3 508.2 0.0 24.5 443.5 40.3 8.7

NH 7202/03 582.6 567.5 0.0 107.5 430.7 29.4 8.3

NH7203/02 532.4 491.8 0.0 28.5 388.3 75.0 18.2 Gunnison 520.1 465.5 10.3 39.6 322.4 93.2 30.6

Bejo Talon 429.8 389.9 0.0 3.3 303.2 83.3 20.3


Table 5. Bolting and maturity at harvest, and bulb quality 2 weeks after harvest for seven onion varieties grown from sets harvested on three dates, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Maturity Bulb quality 2 weeks after harvest

Tops down

Leaf dryness

Sprouted

and decomposed

Total sprouted or

decomposed Company Variety Bolting Sprouted Decomposed

-------------------------------------------------- % --------------------------------------------------------

July 23

Nunhems Arcero 2.2 30 10

0.0 0.0 0.0 0.0

Sabroso 1.6 10 20

0.0 0.0 0.0 0.0

Pulsar 1.6 20 10

0.0 0.5 0.0 0.5

NH 7202/03 0.9 60 20

0.0 0.0 0.0 0.0

NH7203/02 0.3 80 20

0.0 0.5 0.0 0.5

Gunnison 0.6 80 30 0.0 0.0 0.0 0.0 Bejo Talon 14.7 90 30

0.0 0.4 0.0 0.4

Average 3.1 52.9 20.0 0.0 0.2 0.0 0.2

July 30

Nunhems Arcero

50 50

1.1 0.7 0.0 1.8

Sabroso

50 40

1.0 1.0 0.0 1.9

Pulsar

40 30

1.8 1.8 0.0 3.5

NH 7202/03

80 30

0.5 2.7 0.0 3.2

NH7203/02

90 40

1.1 2.1 0.0 3.2

Gunnison

90 50 0.0 1.3 0.0 1.3 Bejo Talon 90 50

0.0 0.7 0.0 0.7

Average 70.0 41.4 0.8 1.5 0.0 2.2

August 6

Nunhems Arcero

80 50

0.0 0.4 0.0 0.4

Sabroso

100 50

0.0 0.4 0.0 0.4

Pulsar

70 40

0.0 1.6 0.0 1.6

NH 7202/03

90 40

0.0 0.4 0.0 0.4

NH7203/02

100 70

0.0 0.4 0.0 0.4

Gunnison 100 60 0.0 0.5 0.5 0.9 Bejo Talon

100 60 0.0 0.3 0.0 0.3

Average 91.4 52.9 0.0 0.6 0.1 0.6

Average over dates

Nunhems Arcero

53.3 36.7

0.4 0.4 0.0 0.7

Sabroso

53.3 36.7

0.3 0.5 0.0 0.8

Pulsar

43.3 26.7

0.6 1.3 0.0 1.9

NH 7202/03

76.7 30.0

0.2 1.0 0.0 1.2

NH7203/02

90.0 43.3

0.4 1.0 0.0 1.3

Gunnison 90.0 46.7 0.0 0.6 0.2 0.7 Bejo Talon 93.3 46.7 0.0 0.5 0.0 0.5


ONION VARIETY RESPONSE TO PLANT POPULATION AND IRRIGATION SYSTEM Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Introduction Changing market opportunities for smaller size onion bulbs and the availability of new onion varieties necessitate evaluations of yield and bulb size response to plant population. These evaluations can aid growers in making planting rate decisions. The objective of this trial was to evaluate the response of four onion varieties to five plant populations under “conventional” drip irrigation, “intense bed” drip irrigation, and furrow irrigation.

Materials and Methods Onions were grown in 2012 on an Owyhee silt loam with a pH of 7.7 and 1.7 percent organic matter, previously planted to wheat. In the fall of 2011, the wheat stubble was shredded and the field was irrigated. The field was then disked, moldboard plowed, and groundhogged. Based on a soil analysis, 100 lb of phosphorus/acre, 200 lbs of sulfur/acre, 1,000 lbs of gypsum/acre, and 1 lb of boron/acre were broadcast before plowing. On September 25, the field was fumigated with Vapam® at 15 gal/acre and bedded at 22 inches. In the spring, the field was divided into irrigation main plots that were 88 inches wide by 136 ft long. The experimental design was a randomized complete block with split-split plots and six replicates. There were three irrigation treatments: “conventional” drip irrigation, “intense bed” drip irrigation, and furrow irrigation. “Intense bed” drip irrigation is a local name used for beds with three drip tapes and six double rows of onions, while “conventional” drip irrigation is a local name used for beds with two drip tapes and four double rows of onions. Each irrigation main plot was divided into 4 split plots that were 30 ft long. Each split plot in each irrigation main plot was planted to one of four onion varieties (‘Vaquero’, Nunhems, Parma, ID; ‘Barbaro’, Seminis, Payette, ID; ‘Sedona’, Bejo, Oceano, CA; ‘Esteem’, Crookham, Caldwell, ID) on April 7, 2011 and on March 12, 2012. The seed was planted in double-rows at 18 seeds/ft of single row. The single rows were spaced 3 inches apart. In the conventional drip and furrow-irrigation plots, the double rows were spaced 22 inches apart (4 double rows on an 88-inch tractor pass). In the intense bed drip plots, the double rows were spaced 12 inches apart (6 double rows on an 88-inch tractor pass). Planting was done with customized John Deere Flexi Planter units equipped with disc openers. Immediately after planting, the double rows of onion seed received a narrow band of Lorsban® 15G at 3.7 oz/1,000 ft of row (0.82 lb ai/acre) and the soil surface was rolled.

Onion Variety Response to Plant Population and Irrigation System 35

In the conventional drip and furrow-irrigation plots, tape (Toro Aqua-Traxx, Toro Co., El Cajon, CA) with emitters spaced 12 inches apart and an emitter flow rate of 0.15 gal/hour was laid at 4-inch depth between 2 double rows at the same time as planting (2 tapes on an 88-inch pass, 44 inches between tapes, 11 inches between the center of double row and drip tape). In the intense bed drip plots, tape (Toro Aqua-Traxx) with emitters spaced 8 inches apart and flow rate of 0.07 gal/hour was laid at 4-inch depth before planting (3 tapes on an 88-inch tractor pass, 22 inches between tapes, 6 inches between center of double row and drip tape). Onion emergence started on April 2. On May 14, alleys 3 ft wide were cut between the variety split plots, leaving plots 30 ft long. Each variety split plot was then divided into 5 population split-split plots 6 ft long. On May 15, the seedlings in each split-split plot of each variety split plot were hand thinned to one of five plant populations (Table 1). After thinning, the drip tape in the furrow irrigation plots was removed and the furrows between onion rows were cultivated to allow for furrow irrigation. Table 1. Target spacing between onion seedlings after thinning and plant density. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Plant Spacing in single row

Plant density population Conventional bed Intense bed Conventional bed Intense bed

plants/acre ------- inches --------

------- plants/ft2 ------- 90,000 6.3 9.5

2.1 2.5

120,000 4.8 7.1

2.8 3.4 160,000 3.6 5.4

3.7 4.5

200,000 2.9 4.3

4.5 5.6 240,000 2.4 3.6 5.5 6.7

The onions were managed to minimize yield reductions from weeds, pests, diseases, water stress, and nutrient deficiencies. On April 16, Prowl® H2O at 0.95 lb ai/acre was applied for weed control. On May 8, Goal® at 0.16 lb ai/acre, Buctril® at 0.19 lb ai/acre, and Poast® at 0.25 lb ai/acre were applied for weed control. The trial was sprayed weekly for thrips control starting on May 30 for a total of 7 applications. The insecticide application sequence included 2 applications of Movento® at 5 oz/acre, followed by 2 applications of Radiant® at 8 oz/acre, followed by 3 applications of Lannate® at 3 pt/acre. Root tissue samples were taken on June 18, July 2, and July 18. Based on the tissue analysis, a total of 150 lb nitrogen/acre, 5 lb magnesium/acre, 5 lb Calcium/acre, and 0.4 lb boron/acre were applied during the season. The nutrients were injected through the drip tape or water-run during irrigations in the furrow-irrigated plots. Onions in each conventional and intense bed drip main plot were irrigated automatically and independently to maintain the soil water tension (SWT) in the onion root zone below 20 cb. Soil water tension was measured in each main plot with four granular matrix sensors (GMS, Watermark Soil Moisture Sensors Model 200SS, Irrometer Co., Riverside, CA) installed at 8-inch depth in the center of the double row. Sensors had been calibrated to SWT (Shock et al. 1998). The GMS were connected to the datalogger via multiplexers (AM 410 multiplexer, Campbell Scientific, Logan, UT). The datalogger read the sensors and recorded the SWT every hour. The datalogger made irrigation decisions for each drip-irrigated main plot every 12 hours.


The individual irrigation decisions for each plot were based on the average SWT. The irrigation durations were 7 hours, 10 min for the conventional drip system and 8 hours, 19 min for the intense bed drip system to supply 0.48 inches of water per irrigation. The irrigations were controlled by the datalogger using a controller (SDM CD16AC controller, Campbell Scientific, Logan, UT) connected to solenoid valves in each plot. The water for the drip and sprinkler plots was supplied by a well that maintained a continuous and constant water pressure of 35 psi. The pressure in the drip lines was maintained at 10 psi by pressure regulators in each plot. The amount of water applied to each plot was recorded daily at 8:00 a.m. from a water meter installed between the solenoid valve and the drip tape. The automated irrigation system was started on June 16 and ended on September 5. Onion evapotranspiration (ETc) was calculated with a modified Penman equation (Wright 1982) using data collected at the Malheur Experiment Station by an AgriMet weather station. Onion ETc was estimated and recorded from crop emergence until the onions were lifted. The furrow-irrigated onions were irrigated manually when the SWT at 8-inch depth reached 25 cb. The field in which this trial was conducted had 1-3 percent slope. To reduce erosion and improve the lateral movement of water during furrow irrigations, straw at 900 lb/acre was applied to the furrow bottoms on May 17. The last furrow irrigation was on August 31. Onions in each split-split plot were evaluated subjectively for the percentage of tops down and leaf dryness on August 17. The number of bolted onions in each split-split plot was determined on August 17. Onions in each split-split plot were evaluated subjectively for severity of symptoms of iris yellow spot virus (IYSV) on September 12. Each plot was given a rating on a scale of 0 to 5 of increasing severity of symptoms. The rating was 0 if there were no symptoms, 1 if 1-25 percent of foliage was diseased, 2 if 26-50 percent of foliage was diseased, 3 if 51-75 percent of foliage was diseased, 4 if 76-99 percent of foliage was diseased, and 5 if 100 percent of foliage was diseased. The onions were lifted on September 13 to field cure. Onions from 5 ft of the middle 2 rows in each conventional drip and furrow-irrigation split-split plot and from 5 ft of the middle 4 rows in the intense bed drip split-split plots were topped by hand and bagged on September 24. Onions were graded on October 4 and 5. During grading all bulbs from each split-split plot were counted. After counting, the bulbs were separated according to quality: bulbs without blemishes (No. 1s), split bulbs (No. 2s), neck rot (bulbs infected with the fungus Botrytis allii in the neck or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold (bulbs infected with the fungus Aspergillus niger). The No. 1 bulbs were graded mechanically (Kerian Speed Sizer, Kerian Machines, Inc., Grafton, ND) according to diameter: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches). Bulb counts per 50 lb of supercolossal onions were determined for each plot of every variety by weighing and counting all supercolossal bulbs during grading. Marketable yield consists of No.1 bulbs larger than 2¼ inches. After grading, 25 bulbs from each plot were separated and individually weighed and measured for diameter to understand the ratio of weight to diameter. The bulb diameter was used to calculate the proportion of size categories by diameter and weight for each plot. The yield of bulbs in onion ring processing size (3¼-4½ inch diameter) was calculated using the bulb proportions by diameter and the plot total yield measured at grading.


Treatment differences were compared using analysis of variance. Means separation was determined using a protected Fisher’s least significant difference test at the 5 percent probability level, LSD (0.05). The least significant difference LSD (0.05) values in each table should be considered when comparisons are made between treatments for significant differences in performance characteristics. Differences between treatments equal to or greater than the LSD value for a characteristic should exist before any treatment is considered different from any other treatment in that characteristic. For the regression analyses, the actual plant population in each split-split plot was calculated from the bulb counts during grading. Regression equations were developed by regression of the yield components against the actual plant population. Results and Discussion Intense bed drip and conventional drip irrigation resulted in more uniform soil moisture over time than furrow irrigation (Fig. 1). From onion emergence to the last irrigation, a total of 36.0 inches of water were applied to the conventional drip irrigation plots and a total of 33.1 inches of water were applied to the intense bed drip irrigation plots. Onion ETc, measured from emergence to the last irrigation, totaled 37.1 inches. For varieties and irrigation systems, the actual plant population achieved was different than the target population (Tables 2-5). Analysis of Variance Irrigation system was not a statistically significant factor in the response of onion bulb size to plant population (Tables 2-5). Averaged over irrigation systems and varieties, marketable yield increased with increasing plant population up to 148,000 plants per acre (Table 5). Yield of medium bulbs increased with increasing plant population up to the highest tested of 190,000 plants per acre. Averaged over irrigation systems and varieties, yield of jumbo bulbs was highest with a plant population of 148,000 plants per acre. Averaged over irrigation systems and varieties, yield of colossal plus supercolossal bulbs decreased with increasing plant population. Averaged over irrigation systems, for all four varieties, yield of colossal plus supercolossal bulbs decreased with increasing plant population (Table 6). Averaged over irrigation systems, for all four varieties, yield of small bulbs increased with increasing plant population. The bulb size percentages and bulb yields for the different size categories for typical onion ring processing can be found in Tables 8 and 9. Irrigation system was not a statistically significant factor in the response of onion yield to plant population. Averaged over irrigation systems and varieties, the percentage and yield of bulbs larger than 4 inches in diameter decreased with increasing plant population up to the highest tested of 189,791 plants per acre. Averaged over irrigation systems and varieties, the percentage and yield of bulbs 3-3¼ inches and less than 3 inches in diameter increased with increasing plant population up to the highest tested of 189,791 plants per acre. Averaged over irrigation systems and varieties, the percentage and yield of bulbs 3¼-4½ inches in diameter decreased with increasing plant population (Tables 8 and 9).


Regression Analysis The response of marketable yields and jumbo yields to plant population varied by variety, population, and irrigation system (Table 7, Figs. 2-11). Yield responses to plant population were similar for conventional bed drip and furrow irrigation systems and different from intense bed drip irrigation. Despite being thinned to the same plant population on a per acre basis as the conventional beds, onions in the intense beds had a higher plant density than the conventional beds (Table 1). The marketable and jumbo yield responses to plant population ranged from none, to linear (yields increased with population), to quadratic (yields increased up to a certain population). For all varieties and irrigation systems, except Vaquero and Esteem under intense bed drip irrigation, marketable yield increased with increasing plant population. For Vaquero and Esteem under intense bed drip irrigation, marketable yield increased up to plant populations of 200,500 and 180,600 plants per acre, respectively. Averaged over varieties and conventional bed irrigation systems, marketable yields increased with increasing plant population (Fig. 10). For the intense bed drip irrigation system, averaged over varieties, marketable yields increased up to a plant population of 210,400 plants per acre (Fig. 11). As the marketable yields increased, average bulb diameter decreased (Fig. 12) with the decrease in colossal bulbs and increase in medium bulbs. Jumbo yield showed a linear increase in response to plant population for all varieties under conventional bed irrigation systems, except Esteem (Figs. 2-9). For Esteem under conventional bed irrigation and all varieties under intense bed drip irrigation, jumbo yield showed a quadratic response to plant population. Under intense bed drip irrigation, jumbo yields increased up to plant populations of 262,900, 223,600, 171,900, and 181,300 plants per acre for Vaquero, Barbaro, Sedona, and Esteem, respectively. For Esteem under conventional drip irrigation, jumbo yields increased up to a plant population of 193,100 plants per acre. For all varieties and irrigation systems, yield of colossal plus supercolossal bulbs decreased and yield of medium and small bulbs increased with increasing plant population (Figs. 2-11). The general responses of bulb market sizes of the varieties to plant populations were similar to the responses found in 2011 (Shock et al. 2012). In 2012, irrigation systems were also not much of a factor in onion response to plant population. For Vaquero, the yield of bulbs 3¼-4½ inches in diameter showed a quadratic response to plant population, with the highest yield at 134,828 plants per acre (Fig. 13). For Barbaro, the yield of bulbs 3¼-4½ inches in diameter was not responsive to plant population (Fig. 14), but the average size of bulbs in the 3¼- to 4½-inch category would decrease with increasing population. The percentage of bulbs larger than 3 inches in diameter had a weak linear decrease with increasing plant population, but remained higher than 80 percent up to the highest population tested (Figs. 15-18). Irrigation system was not a statistically significant factor in the response of bolting and percentage of tops down to plant population (Tables 2-5). For all varieties except Barbaro, bolting increased with increasing plant population (Figs. 19- 22). For Barbaro, bolting was not affected by plant population. For all varieties, the percentage of tops down on August 17 increased with increasing plant population (Figs. 23-26).


Limitations If the length of the irrigation furrows had been of normal field size, 600 to 1,200 ft, we would anticipate greater possibility of uneven water delivery under furrow irrigation and poorer onion performance than what was observed in this trial. The silt loam soil used in this trial has excellent lateral water movement. If the soil had not transmitted moisture well, the intense bed drip irrigation systems should have shown an advantage over conventional drip irrigation, because the bulbs grew closer to the drip tapes.

References Shock, C.C., J.M. Barnum, and M. Seddigh. 1998. Calibration of Watermark Soil Moisture

Sensors for irrigation management. Pages 139-146 in Proceedings of the International Irrigation Show, Irrigation Association, San Diego, CA.

Shock, C.C., E. Feibert, and L.D. Saunders. 2012. Response of four onion varieties to plant population and irrigation system. Oregon State University Agricultural Experiment Station Annual Report 2011, Ext/Crs 141, pages 40-65.

Wright, J.L. 1982. New evapotranspiration crop coefficients. Journal of Irrigation and Drainage Division, American Society of Civil Engineers 108:57-74.


Figure 1. Soil water tension over time for three irrigation systems in onions. Malheur Experiment Station, Oregon State University, Ontario, OR.


Table 2. Onion yield and grade in response to plant population for four varieties grown with conventional drip irrigation. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Plant population Total yield

Marketable yield by grade Unmarketable

Tops Variety Target Actual Total >4 in >4¼ in 4-4¼ in 3-4 in 2¼-3 in <2¼ in Doubles Rot Bolting down IYSV

--- plants/acre --- --------------------------------------------------- cwt/acre ------------------------------------------------ --------- % --------- 0-5

Vaquero 90,000 90,290 1060.5 1046.5 794.3 250.4 543.8 240.6 11.7

8.1 0.0 0.5 0.8 36.0 0.8

120,000 105,496 1058.3 1050.1 593.4 107.3 486.1 439.1 17.6

8.2 0.0 0.0 1.4 48.0 0.8

160,000 143,038 1308.7 1282.2 641.2 81.5 559.7 592.0 49.0

26.5 0.0 0.0 0.9 48.0 0.8

200,000 164,422 1201.7 1154.2 359.8 23.3 336.5 698.6 95.8

30.0 0.0 1.5 5.6 74.0 0.8

240,000 187,707 1263.9 1225.2 200.5 24.7 175.8 928.6 96.1

34.8 0.0 0.3 3.7 72.0 0.8

average 138,191 1178.6 1151.6 517.8 97.4 420.4 579.8 54.0 21.5 0.0 0.5 2.5 55.6 0.8 Barbaro 90,000 88,389 957.7 947.3 631.9 220.6 411.3 300.0 15.3

5.5 0.0 0.5 0.0 18.3 1.4

120,000 109,298 1029.5 1013.1 497.6 111.9 385.8 466.6 48.9

10.7 0.0 0.5 0.2 18.3 1.4

160,000 137,335 1115.1 1096.9 445.3 69.5 375.8 592.0 59.6

18.2 0.0 0.0 0.1 26.7 1.4

200,000 164,897 1141.1 1097.8 268.4 28.7 239.7 732.0 97.4

35.4 0.0 0.6 1.4 38.3 1.4

240,000 182,480 1187.5 1137.6 190.4 23.4 167.0 829.2 117.9

34.2 0.0 1.2 0.6 38.3 1.4

average 136,480 1086.2 1058.5 406.7 90.8 315.9 584.0 67.8 20.8 0.0 0.6 0.5 28.0 1.4 Sedona 90,000 88,706 885.2 878.4 503.7 120.8 382.9 336.3 38.4

6.8 0.0 0.0 0.5 31.7 1.0

120,000 113,654 940.8 924.5 340.3 71.0 269.4 534.4 49.8

16.2 0.0 0.0 1.5 33.3 1.0

160,000 144,147 1031.2 1003.6 235.6 25.6 210.0 692.9 75.1

27.6 0.0 0.0 3.2 45.0 1.0

200,000 159,987 1018.8 984.9 260.4 24.9 235.5 617.4 107.1

29.0 0.0 0.5 5.4 58.3 1.0

240,000 180,579 1101.9 1027.6 160.9 11.6 149.4 764.5 102.1

58.5 3.1 1.3 5.8 65.0 1.0

average 137,414 995.6 963.8 300.2 50.8 249.5 589.1 74.5 27.6 0.6 0.4 3.3 46.7 1.0 Esteem 90,000 90,290 884.6 875.6 423.8 76.9 346.9 429.8 21.9

7.1 0.0 0.2 0.3 35.0 0.9

120,000 118,802 984.9 964.6 351.5 34.9 316.6 575.8 37.3

15.8 0.0 0.4 0.3 45.0 0.9

160,000 153,651 1082.1 1056.5 238.3 26.2 212.1 722.7 95.4

25.7 0.0 0.0 1.4 48.3 0.9

200,000 164,343 1081.3 1044.9 114.0 5.1 108.8 845.6 85.4

36.4 0.0 0.0 1.9 63.3 0.9

240,000 189,687 1028.3 973.1 97.1 4.5 92.6 718.5 157.5

53.9 0.0 0.1 3.2 65.0 0.9

average 143,355 1012.2 982.9 244.9 29.5 215.4 658.5 79.5 27.8 0.0 0.2 1.4 51.3 0.9 LSD (0.05)

Irrigation X Variety NS NS NS NS 26.3 NS 57.5 NS

NS NS NS NS NS NS Irr. X Var. X Population NS NS NS NS 65.6 NS NS NS NS NS NS NS NS NS

Table 3. Onion yield and grade in response to plant population for four varieties grown with intense bed drip irrigation. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Plant population

Total yield Marketable yield by grade

Unmarketable

Tops

Variety Target Actual Total >4 in >4¼ in 4-4¼ in 3-4 in 2¼-3 in <2¼ in Doubles Rot Bolting down IYSV

--- plants/acre --- --------------------------------------------------- cwt/acre ----------------------------------------------- -----------% ---------- 0 - 5

Vaquero 90,000 89,696 897.8 890.4 534.0 91.7 442.4 332.3 24.1

6.7 0.0 0.1 0.7 23.3 0.8

120,000 124,445 972.9 955.5 317.7 21.8 295.9 592.3 45.5

17.4 0.0 0.0 3.3 48.3 0.8

160,000 162,759 1087.6 1050.6 227.7 22.8 205.0 714.0 108.8

24.9 0.0 1.1 3.7 55.0 0.8

200,000 184,143 1186.8 1134.1 128.8 0.0 128.8 866.5 138.8

38.3 0.0 1.3 4.4 75.0 0.8

240,000 213,547 1150.8 1081.6 119.3 8.6 110.7 766.9 195.5

60.7 0.0 0.7 7.9 80.0 0.8

average 154,918 1059.2 1022.4 265.5 29.0 236.5 654.4 102.5 29.6 0.0 0.6 4.0 56.3 0.8 Barbaro 90,000 98,606 983.9 978.6 566.7 153.5 413.2 380.5 31.4

5.3 0.0 0.0 0.0 13.3 1.4

120,000 128,306 1065.8 1040.7 448.9 87.5 361.4 535.7 56.1

14.9 0.0 0.9 0.1 20.0 1.4

160,000 155,750 1115.2 1075.7 225.5 27.7 197.9 759.8 90.4

18.5 0.0 2.0 0.1 18.3 1.4

200,000 185,925 1152.1 1113.7 173.2 9.8 163.4 812.3 128.2

36.5 0.0 0.2 1.0 35.0 1.4

240,000 218,834 1233.9 1154.9 157.5 31.6 126.0 832.6 164.8

62.1 0.0 1.5 2.3 38.3 1.4

average 157,484 1110.2 1072.7 314.4 62.0 252.4 664.2 94.2 27.5 0.0 0.9 0.7 25.0 1.4 Sedona 90,000 93,022 795.9 784.0 261.7 71.1 190.6 488.7 33.6

9.8 0.0 0.3 0.9 20.0 1.0

120,000 127,950 907.0 884.9 205.1 21.2 183.9 585.6 94.2

15.8 5.1 0.1 3.3 40.0 1.0

160,000 154,680 925.9 865.1 82.9 0.0 82.9 659.0 123.2

43.1 0.0 1.8 3.3 36.7 1.0

200,000 184,262 983.7 919.2 102.6 4.0 98.7 640.8 175.8

61.4 0.0 0.3 3.9 61.7 1.0

240,000 202,082 1009.3 907.3 131.6 2.9 128.7 618.0 157.7

75.8 3.9 2.2 11.0 56.7 1.0

average 152,399 924.3 872.1 156.8 19.8 137.0 598.4 116.9 41.2 1.8 0.9 4.5 43.0 1.0 Esteem 90,000 91,775 778.6 765.6 265.0 4.4 260.7 476.9 23.6

10.5 0.0 0.3 0.2 25.0 0.9

120,000 144,345 952.0 924.5 111.1 8.8 102.3 721.4 92.1

25.9 0.0 0.1 2.2 46.7 0.9

160,000 167,214 977.8 937.1 104.8 4.3 100.4 711.0 121.2

30.5 0.0 1.1 3.5 50.0 0.9

200,000 196,024 1000.7 934.3 47.1 0.0 47.1 727.8 159.4

61.1 0.0 0.5 2.6 50.0 0.9

240,000 215,329 998.2 895.6 13.5 0.0 13.5 667.3 214.9

84.1 0.0 1.7 4.7 61.7 0.9

average 162,937 941.4 891.4 108.3 3.5 104.8 660.9 122.2 42.4 0.0 0.8 2.6 46.7 0.9 LSD (0.05)



Table 4. Onion yield and grade in response to plant population for four varieties grown with furrow irrigation and for the overall average. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Marketable yield by grade Unmarketable

Tops Variety Target Actual Total >4 in >4¼ in 4-4¼ in 3-4 in 2¼-3 in <2¼ in Doubles Rot Bolting down IYSV

--- plants/acre --- -------------------------------------------------- cwt/acre ------------------------------------------------ ---------- % ---------- 0 - 5

Vaquero 90,000 97,022 1154.6 1142.1 845.2 358.8 486.5 288.8 8.0

6.3 0.0 0.5 1.2 26.7 1.0

120,000 114,050 1129.1 1124.6 610.2 115.2 495.1 490.3 24.1

2.0 0.0 0.2 5.0 35.0 1.0

160,000 141,375 1165.4 1146.7 362.8 39.2 323.6 736.5 47.4

16.6 0.0 0.2 5.1 51.7 1.0

200,000 158,007 1174.6 1143.1 296.1 6.1 290.0 791.8 55.2

25.0 0.0 0.6 5.9 65.0 1.0

240,000 172,263 1098.1 1059.4 173.1 7.0 166.2 776.0 110.2

38.4 0.0 0.0 9.7 73.3 1.0

average 136,543 1144.4 1123.2 457.5 105.2 352.3 616.7 49.0 17.7 0.0 0.3 5.4 50.3 1.0 Barbaro 90,000 91,082 996.8 982.7 673.8 213.1 460.7 288.0 20.9

7.1 0.0 0.6 0.0 16.7 1.5

120,000 100,190 905.8 879.8 463.6 150.0 313.6 377.4 38.8

14.0 0.0 1.6 1.6 18.3 1.5

160,000 136,622 1154.2 1111.3 507.0 125.1 381.9 551.2 53.1

12.6 0.0 2.4 0.6 21.7 1.5

200,000 149,295 1161.6 1114.2 440.5 57.0 383.5 613.7 60.0

26.8 0.0 1.8 0.6 21.7 1.5

240,000 171,867 1216.9 1165.8 379.1 79.4 299.6 689.6 97.1

44.7 0.0 0.6 1.7 23.3 1.5

average 129,811 1087.1 1050.8 492.8 124.9 367.9 504.0 54.0 21.1 0.0 1.4 0.9 20.3 1.5 Sedona 90,000 93,854 894.9 886.2 410.8 34.5 376.3 456.4 19.0

8.6 0.0 0.0 4.9 28.3 1.1

120,000 115,238 899.9 873.3 240.9 33.7 207.3 590.7 41.7

22.5 2.4 0.2 6.5 35.0 1.1

160,000 144,939 963.6 919.6 146.9 15.8 131.1 684.6 88.1

32.2 0.0 1.2 7.7 38.3 1.1

200,000 156,423 957.1 920.5 251.9 43.4 208.5 582.1 86.5

29.9 1.0 0.5 6.4 33.3 1.1

240,000 169,095 994.7 950.2 73.3 6.7 66.5 737.9 139.0

35.9 0.0 0.9 4.3 36.7 1.1

average 135,910 942.0 910.0 224.8 26.8 197.9 610.3 74.8 25.8 0.7 0.6 6.0 34.3 1.1 Esteem 90,000 94,646 816.9 800.2 330.1 87.9 242.2 448.9 21.1

12.0 0.0 0.5 2.4 35.0 0.9

120,000 112,070 898.2 886.0 307.4 58.8 248.6 529.5 49.1

12.2 0.0 0.0 4.5 40.0 0.9

160,000 133,454 1048.0 1021.8 237.9 11.1 226.8 714.7 69.1

18.6 0.0 0.8 6.5 43.3 0.9

200,000 159,987 1000.9 963.8 89.2 6.2 83.0 781.4 93.2

37.1 0.0 0.0 4.9 55.0 0.9

240,000 177,253 1024.7 966.9 72.9 0.0 72.9 763.4 130.6

55.4 0.0 0.2 7.1 66.7 0.9

average 135,482 957.7 927.7 207.5 32.8 174.7 647.6 72.6 27.0 0.0 0.3 5.1 48.0 0.9 LSD (0.05)



Table 5. Onion yield and grade in response to plant population for three irrigation systems averaged over four varieties and for the overall average. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Irrigation system Plant population

Total yield Marketable yield by grade Unmarketable

Tops

Target Actual Total >4 in >4¼ in 4-4¼ in 3-4 in 2¼-3 in <2¼ in Doubles Rot Bolting down IYSV

--- plants/acre --- -------------------------------------------------- cwt/acre ----------------------------------------------- ----------- % ------------ 0-5

Conventional drip 90,000 89,426 941.4 931.5 577.1 161.0 416.1 331.8 22.6

6.9 0.0 0.3 0.4 30.0 1.0

120,000 112,214 999.7 984.1 436.7 78.7 358.0 508.6 38.9

13.0 0.0 0.2 0.9 35.7 1.0

160,000 144,939 1127.2 1102.5 376.2 48.4 327.7 655.2 71.2

24.7 0.0 0.0 1.5 41.7 1.0

200,000 163,299 1105.2 1065.4 244.9 20.0 224.9 724.1 96.4

32.7 0.0 0.6 3.6 57.8 1.0

240,000 185,115 1138.1 1082.6 159.2 15.3 143.9 804.0 119.4

46.3 0.8 0.7 3.5 59.6 1.0

average 138,999 1062.3 1033.2 358.8 64.7 294.1 604.7 69.7 24.7 0.2 0.4 2.0 45.0 1.0 Intense bed 90,000 93,286 867.0 857.7 413.2 80.5 332.6 416.6 28.0

8.0 0.0 0.2 0.4 20.4 1.0

120,000 131,406 977.4 954.3 273.5 35.4 238.1 609.8 71.0

18.6 1.1 0.3 2.2 38.8 1.0

160,000 160,545 1027.2 983.2 160.8 13.7 147.1 711.1 111.3

29.1 0.0 1.4 2.8 40.0 1.0

200,000 187,733 1085.1 1029.9 113.4 3.4 110.0 767.1 149.4

48.8 0.0 0.6 3.0 55.4 1.0

240,000 212,629 1095.9 1007.9 101.9 10.2 91.8 720.8 185.2

70.8 0.9 1.5 6.5 59.2 1.0

average 157,120 1010.5 966.6 212.6 28.6 183.9 645.1 109.0 35.1 0.4 0.8 3.0 42.8 1.0 Furrow 90,000 94,151 965.8 952.8 565.0 173.6 391.4 370.5 17.3

8.5 0.0 0.4 2.1 26.7 1.1

120,000 110,387 958.3 940.9 405.6 89.4 316.2 497.0 38.4

12.7 0.6 0.5 4.4 32.1 1.1

160,000 139,098 1082.8 1049.8 313.7 47.8 265.9 671.8 64.4

20.0 0.0 1.1 5.0 38.8 1.1

200,000 155,928 1073.6 1035.4 269.4 28.2 241.3 692.2 73.7

29.7 0.3 0.7 4.5 43.8 1.1

240,000 172,418 1086.2 1038.5 179.0 24.3 154.7 740.8 118.7

43.1 0.0 0.5 5.6 50.0 1.1

average 134,396 1033.3 1003.5 346.5 72.7 273.9 594.5 62.5 22.8 0.2 0.6 4.3 38.3 1.1 Average 90,000 92,356 925.1 914.3 518.2 138.6 379.7 373.5 22.5

7.8 0.0 0.3 1.0 25.6 1.1

120,000 117,976 977.8 959.2 371.5 68.0 303.5 538.3 49.4

14.8 0.6 0.4 2.5 35.5 1.1

160,000 147,926 1079.2 1045.3 284.4 37.0 247.5 679.1 81.8

24.5 0.0 0.9 3.1 40.1 1.1

200,000 168,880 1087.5 1043.1 209.6 17.3 192.3 727.4 106.2

37.0 0.1 0.6 3.7 52.3 1.1

240,000 189,791 1106.4 1043.0 147.2 16.7 130.5 755.0 140.8 53.3 0.6 0.9 5.2 56.7 1.1 LSD (0.05)

Irrigation

9322 NS NS NS NS NS NS 8.5

NS NS NS NS NS NS Population

3537 30.0 31.0 46.8 19 40.3 36.8 11.1

4.2 NS NS 0.9 4.0 NS

Irrigation X Population 6126 NS NS NS NS NS NS 19.3 7.2 NS 0.7 NS 6.9 NS

Table 6. Onion yield and grade in response to plant population for four varieties averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Marketable yield by grade Unmarketable Variety Target Actual Total >4 in >4¼ in 4-4¼ in 3-4 in 2¼-3 in

<2¼ in Doubles Rot

--- plants/acre --- -------------------------------------------------- cwt/acre ------------------------------------------------- %

Vaquero 90,000 92,456 1036.3 1025.2 720.4 232.6 487.8 290.0 14.8

7.0 0.0 0.3

120,000 115,203 1053.2 1043.0 502.0 79.9 422.1 511.2 29.7

9.2 0.0 0.1

160,000 149,411 1180.1 1152.6 397.0 45.8 351.2 686.1 69.5

22.5 0.0 0.4

200,000 169,118 1186.9 1143.2 255.8 9.0 246.8 790.7 96.6

31.2 0.0 1.1

240,000 191,376 1165.5 1116.0 162.2 12.7 149.4 817.7 136.2

45.2 0.0 0.4

average 143,513 1124.4 1096.0 407.5 76.0 331.5 619.1 69.4 23.0 0.0 0.5 Barbaro 90,000 92,945 980.7 970.9 623.7 194.3 429.4 324.2 23.0

6.0 0.0 0.3

120,000 112,792 998.7 975.8 468.4 116.7 351.7 459.5 47.9

13.4 0.0 1.0

160,000 142,822 1129.8 1095.7 399.7 77.3 322.5 629.2 66.8

16.2 0.0 1.5

200,000 166,812 1152.2 1109.2 295.6 32.0 263.5 718.6 95.1

32.7 0.0 0.9

240,000 189,861 1213.0 1153.6 250.9 47.0 203.9 777.9 124.8

46.8 0.0 1.1

average 141,047 1094.9 1061.0 407.7 93.4 314.2 581.9 71.5 23.0 0.0 1.0 Sedona 90,000 91,792 862.3 853.4 399.7 75.7 324.0 423.5 30.1

8.3 0.0 0.1

120,000 118,418 916.4 894.8 265.5 43.2 222.3 569.3 60.0

18.3 2.3 0.1

160,000 147,524 976.4 933.2 159.4 14.6 144.8 680.0 93.8

33.8 0.0 0.9

200,000 165,869 986.7 942.8 211.0 25.3 185.8 611.8 120.0

38.8 0.4 0.4

240,000 182,851 1036.9 964.9 121.4 7.3 114.1 712.0 131.5

55.6 2.2 1.4

average 141,291 955.7 917.8 231.4 33.2 198.2 599.3 87.1 31.0 1.0 0.6 Esteem 90,000 92,237 826.7 813.8 339.7 56.4 283.3 451.9 22.2

9.8 0.0 0.3

120,000 125,072 945.0 925.1 256.6 34.2 222.5 608.9 59.5

18.0 0.0 0.2

160,000 151,440 1036.0 1005.1 193.7 13.9 179.8 716.2 95.3

24.9 0.0 0.6

200,000 173,451 1027.6 981.0 83.4 3.8 79.6 784.9 112.7

44.8 0.0 0.2

240,000 195,080 1016.6 943.9 60.5 1.6 58.9 713.6 169.8

65.0 0.0 0.7

average 147,456 970.4 933.8 186.8 22.0 164.8 655.1 91.9 32.5 0.0 0.4 LSD (0.05)

Variety

NS NS NS 40.6 NS 35.7 NS NS

4.5 0.7 NS Variety X Population NS NS NS 93.6 37.9 NS 73.5 NS NS NS NS

Table 7. Regression equation parameters for regressions of plant population and onion yield categories for four varieties and three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Irrigation system Variety Total marketable

Colossal plus supercolossal, >4 in

Jumbo, 3-4 in

intercept linear quadratic R2 P



Conv. Drip Vaquero 785 0.00265

0.41 0.001

1082 -0.00409

0.37 0.01

-237 0.005906

0.82 0.001

Barbaro 739 0.00234

0.36 0.01

891 -0.00355

0.36 0.01

-80.6 0.004870

0.73 0.001

Sedona 635 0.00239

0.35 0.001

625 -0.00236

0.19 0.05

33.0 0.004047

0.50 0.001

Esteem 734 0.00174

0.20 0.05 693 -0.00313 0.40 0.001 -572 0.014290 -3.72.0 X 10-8 0.62 0.001 Intense bed Vaquero 133 0.01003 -2.53 X 10-8 0.52 0.001

727 -0.00298

0.48 0.001

-374 0.009989 -1.986 X 10-8 0.78 0.001

Barbaro 843 0.00146

0.18 0.05

905 -0.00375

0.52 0.001

-763 0.01476 -3.36 X 10-8 0.70 0.001

Sedona 696 0.00115

0.14 NS

332 -0.00115

0.11 NS

-186 0.00997 -2.95 X 10-8 0.46 0.01

Esteem 100 0.00975 -2.78 X 10-8 0.40 0.01 433 -0.00199 0.67 0.001 -410 0.01306 -3689 X 10-8 0.58 0.001 Furrow Vaquero 1078 0.00033 0.01 NS

1420 -0.00700

0.52 0.001

-1689 0.02848 -8.09 X 10-8 0.71 0.001

Barbaro 550 0.00386

0.50 0.001

671 -0.00137

0.05 NS

-69.6 0.00442

0.65 0.001

Sedona 639 0.00199

0.19 0.05

563 -0.00249

0.14 0.05

173 0.00322

0.30 0.01

Esteem 598 0.00245 0.18 0.05 647 -0.00325 0.28 0.010 13.9 0.00470 0.53 0.001 Medium, 2¼-3 in

Small, <2¼ in

Conv. Drip Vaquero -60.5 0.00083

0.47 0.001

-22.4 0.000318

0.71 0.001

Barbaro -71.5 0.00102

0.72 0.001

-27.8 0.000357

0.72 0.001

Sedona -22.6 0.00071

0.41 0.001

-26.1 0.000391

0.42 0.001 Esteem -95.5 0.00122

0.59 0.001 -31.0 0.000410 0.67 0.001

Intense bed Vaquero -4.6 -0.0000880 4.615 X 10-9 0.84 0.001

16.1 -0.000261 2.06 X 10-9 0.72 0.001 Barbaro -81.3 0.00111

0.71 0.001

-37.4 0.000411

0.55 0.001

Sedona -289 0.00446 -1.10 X 10-8 0.88 0.001

-54.6 0.000629

0.71 0.001 Esteem -119 0.00148 0.80 0.001 68.6 -0.001136 5.55 X 10-9 0.70 0.001 Furrow Vaquero -88.2 0.00101

0.51 0.001

56.7 -0.001060 5.0 X 10-9 0.63 0.001

Barbaro 104 -0.00165 9.12 X 10-9 0.70 0.001

44.6 -0.000735 3.10 X 10-9 0.60 0.001

Sedona -97.2 0.00127

0.61 0.001

-17.2 0.000317

0.45 0.001

Esteem -63.4 0.00100 0.40 0.001 -38.0 0.000478 0.57 0.001

Table 8. Response of proportions of bulb size categories to plant population for four onion varieties averaged over three irrigation systems; data were calculated from bulb diameter measurements. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Plant population Proportion by bulb diameter Variety Target Actual >4½ in 4-4½ in 3¼-4 in 3-3¼ in 3¼-4½ in <3 in >3 in

--- plants/acre ---

--------------------------------------- % -------------------------------------

Vaquero 90,000 92,456

16.0 40.8 34.5 6.8 75.3 1.5 98.0

120,000 115,203

5.4 25.2 48.5 15.3 73.6 5.6 94.4

160,000 149,411

2.4 18.4 49.4 18.8 67.8 11.1 88.9

200,000 169,118

1.9 15.3 51.3 20.9 66.6 10.4 89.4

240,000 191,376

0.5 8.0 47.3 30.8 55.3 13.4 86.6

average 143,513 5.1 21.3 46.3 18.7 67.6 8.5 91.4 Barbaro 90,000 92,945

8.9 27.1 45.2 13.6 72.2 4.5 94.8

120,000 112,792

4.2 20.9 49.4 16.5 70.4 8.9 91.1

160,000 142,822

2.5 13.5 45.3 27.3 58.8 11.3 88.5

200,000 166,812

1.2 9.6 47.1 31.8 56.7 10.1 89.6

240,000 189,861

1.8 11.8 48.3 28.5 60.0 9.8 90.3

average 140,437 3.8 16.7 47.0 23.4 63.7 8.9 90.9 Sedona 90,000 91,792

2.4 22.1 53.2 16.5 75.3 5.9 94.1

120,000 118,418

1.4 11.8 43.1 28.7 54.8 14.8 84.9

160,000 147,524

0.2 4.7 52.5 29.6 57.2 12.9 87.1

200,000 165,869

0.0 3.8 49.4 35.3 53.2 11.5 88.5

240,000 182,851

0.2 5.6 45.6 30.8 51.3 17.4 82.4

average 141,291 0.8 9.6 48.8 28.2 58.4 12.5 87.4 Esteem 90,000 92,237

4.7 19.5 51.1 19.5 70.6 5.2 94.8

120,000 125,072

1.6 14.9 46.9 26.9 61.8 9.8 90.2

160,000 151,440

0.9 6.2 47.1 27.6 53.3 18.2 81.8

200,000 173,451

0.4 4.2 51.1 32.9 55.3 11.3 88.7

240,000 195,080

0.2 2.8 37.6 36.5 40.5 22.8 77.2

average 146,921 1.5 9.5 46.8 28.7 56.3 13.5 86.5 Average 90,000 92,356

7.9 27.2 46.1 14.2 73.3 4.3 95.4

120,000 117,976

3.1 18.1 47.0 21.9 65.1 9.8 90.1

160,000 147,926

1.5 10.6 48.6 25.8 59.2 13.5 86.5

200,000 168,880

0.9 8.2 49.7 30.3 57.9 10.8 89.0

240,000 189,791 0.7 7.0 44.7 31.7 51.6 15.9 84.0 LSD (0.05)

Population

1.1 2.8 NS 3.7 4.3 3.1 3.1 Variety X Population 2.2 5.5 7.5 NS NS NS NS


Table 9. Response of yield bulb size categories to plant population for four onion varieties averaged over three irrigation systems; data were calculated from bulb diameter and bulb weight measurements. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Plant population Yield by bulb diameter Variety Target Actual >4½ in 4-4½ in 3¼-4 in 3-3¼ in 3¼-4½ in <3 in >3 in

--- plants/acre ---

---------------------------------- cwt/acre -----------------------------------

Vaquero 90,000 92,456

180.4 442.2 362.7 69.4 804.9 16.5 1054.6

120,000 115,203

60.8 272.0 504.8 156.6 776.8 58.9 994.3

160,000 149,411

31.0 222.4 574.1 220.5 796.5 132.2 1047.9

200,000 169,118

21.3 188.1 612.7 246.6 800.8 115.1 1068.7

240,000 191,376

5.3 93.9 557.1 356.9 651.0 152.3 1013.2

average 143,513 58.3 241.4 524.2 211.7 765.5 95.9 1035.5 Barbaro 90,000 92,945

92.1 273.4 439.6 126.5 713.0 41.8 931.6

120,000 112,792

45.1 218.1 493.6 156.3 711.7 85.5 913.2

160,000 142,822

29.5 152.9 516.0 303.1 668.9 125.8 1001.5

200,000 166,812

14.9 116.1 546.8 358.8 662.9 112.7 1036.6

240,000 189,861

21.0 147.8 581.8 342.5 729.6 119.9 1093.1

average 140,437 40.9 182.4 514.8 255.9 697.2 96.5 993.9 Sedona 90,000 91,792

21.3 195.5 459.6 137.5 655.1 48.4 814.0

120,000 118,418

13.8 114.4 399.3 253.5 513.7 133.0 781.0

160,000 147,524

2.3 48.8 510.6 285.9 559.4 128.7 847.7

200,000 165,869

0.0 38.9 499.8 336.7 538.7 111.3 875.4

240,000 182,851

2.9 64.6 485.2 303.1 549.8 178.9 855.8

average 141,291 8.1 92.4 470.9 263.3 563.3 120.1 834.7 Esteem 90,000 92,237

44.4 173.1 422.9 159.6 596.0 41.1 800.0

120,000 125,072

15.2 144.8 447.2 245.8 592.0 92.0 853.1

160,000 151,440

10.1 69.8 496.7 278.7 566.5 180.7 855.3

200,000 173,451

4.4 45.9 533.1 335.5 579.0 108.8 918.9

240,000 195,080

2.4 30.3 385.6 368.6 416.0 229.6 787.0

average 146,921 15.1 92.6 458.3 277.9 550.9 130.3 844.0 Average 90,000 92,356

83.1 268.5 422.1 124.0 690.6 37.3 897.7

120,000 117,976

33.5 186.7 461.0 203.7 647.7 92.3 884.9

160,000 147,926

17.9 122.3 524.1 271.7 646.3 142.6 935.9

200,000 168,880

10.1 96.5 547.9 319.6 644.4 111.9 974.1

240,000 189,791 7.7 83.2 501.3 342.8 584.5 170.9 935.0 LSD (0.05)

Population

3,537

12.3 31.4 40.2 38.3 50.1 33.2 54.5 Variety X Population NS 24.6 62.7 NS NS NS NS NS


Figure 2. Yield response of onion bulb size categories to plant population for Vaquero averaged over conventional bed drip and furrow irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 3. Yield response of onion bulb size categories to plant population for Vaquero under intense bed drip irrigation. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 4. Yield response of onion bulb size categories to plant population for Barbaro averaged over conventional bed drip and furrow irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 5. Yield response of onion bulb size categories to plant population for Barbaro under intense bed drip irrigation. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 6. Yield response of onion bulb size categories to plant population for Sedona averaged over conventional bed drip and furrow irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 7. Yield response of onion bulb size categories to plant population for Sedona under intense bed drip irrigation. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 8. Yield response of onion bulb size categories to plant population for Esteem averaged over conventional bed drip and furrow irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 9. Yield response of onion bulb size categories to plant population for Esteem under intense bed drip irrigation. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 10. Yield response of onion bulb size categories to plant population averaged over three varieties and over conventional bed drip and furrow irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 11. Yield response of onion bulb size categories to plant population under intense bed drip irrigation and averaged over three varieties. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 12. Onion bulb diameter in response to plant population averaged over three varieties and over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 13. Yield of bulbs in onion ring processing size (3¼-4½ inch diameter) in response to plant population for Vaquero averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 14. Yield of bulbs in onion ring processing size (3¼-4½ inch diameter) in response to plant population for Barbaro averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 15. Percentage of bulbs larger than 3 inch diameter in response to plant population for Vaquero averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 16. Percentage of bulbs larger than 3 inch diameter in response to plant population for Barbaro averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 17. Percentage of bulbs larger than 3 inch diameter in response to plant population for Sedona averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 18. Percentage of bulbs larger than 3 inch diameter in response to plant population for Esteem averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 19. Bolting response to plant population for Vaquero averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 20. Bolting response to plant population for Barbaro averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 21. Bolting response to plant population for Sedona averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 22. Bolting response to plant population for Esteem averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 23. Response of percentage of tops down on August 17 to plant population for Vaquero averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 24. Response of percentage of tops down on August 17 to plant population for Barbaro averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Figure 25. Response of percentage of tops down on August 17 to plant population for Sedona averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 26. Response of percentage of tops down on August 17 to plant population for Esteem averaged over three irrigation systems. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


INSECTICIDE ROTATIONS FOR THRIPS CONTROL IN ONIONS, 2012 Clinton C. Shock, Erik B. G. Feibert, Kenzie J. Barlow, Ashley L. Rock, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR

Eric Jemmett, Jemmett Consulting and Research Farm, Parma, ID Stuart Reitz, Malheur County Extension, Ontario, OR

Introduction Onion thrips and the iris yellow spot virus (IYSV) that these thrips can transmit are major production limiting factors in the Treasure Valley. There are about 20,000 acres of onions produced within a 50-mile radius of Ontario, Oregon. This high concentration of onions makes for unique production challenges, especially for onion thrips and IYSV management. Thrips can rapidly develop resistance to insecticides, and new insecticides may rapidly lose their effectiveness. Therefore, it is important to assess the effectiveness of currently registered insecticides and to develop alternative management methods as part of an overall integrated pest management (IPM) program. A field experiment was conducted to evaluate six currently registered insecticides and one nonregistered insecticide applied in different rotation patterns.

Materials and Methods Onions were grown on an Owyhee silt loam with a pH of 7.7 and 1.7 percent organic matter, previously planted to wheat. In the fall of 2011, the wheat stubble was shredded and the field was irrigated. Based on a soil analysis, 100 lb of phosphorus/acre, 200 lbs of sulfur/acre, 1,000 lbs of gypsum/acre, and 1 lb of boron/acre were broadcast. The field was then disked, moldboard plowed, and groundhogged. On September 25, the field was fumigated with Vapam® at 15 gal/acre and bedded at 22 inches.

Onion seed (‘Vaquero’; Nunhems, Parma, ID) was planted on March 13 in double rows, spaced 3 inches apart using 150,000 seeds/acre. Each double row was planted on beds spaced 22 inches apart. Planting was done with a Beck planter. Onions were grown under drip irrigation. Drip tape (Toro Aqua-Traxx, Toro Co., El Cajon, CA) with emitters spaced 12 inches apart and an emitter flow rate of 0.22 gal/minute/100 ft was laid 2-4 inches deep between 2 onion beds at the time of planting. The distance between the tape and the center of each bed was 11 inches. The water application rate was 0.06 inch/hour. Immediately after planting, Lorsban® 15G insecticide was banded at 3.7 oz/1,000 ft of row (0.82 lbs ai/acre), and the soil surface was rolled.

The field was irrigated as necessary to maintain soil water tension at 20 cb at 8-inch depth. Soil water tension was monitored by six granular matrix sensors (Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside, CA) centered at 8-inch depth below the onion row. The sensors were automatically read three times a day with an AM-400 meter (Mike Hansen Co., East Wenatchee, WA).

Insecticide Rotations for Thrips Control in Onions, 2012 63

Onion emergence started on April 12. Weekly thrips counts were made, starting on May 14. Thrips counts were made by counting the number of thrips on 15 consecutive plants in one of the middle 2 rows of each plot. Each treatment plot was 4 double rows wide by 27 ft long.

Insecticides were applied weekly beginning May 30, according to the schedule and rates listed in Tables 1 and 2. Fifteen treatments were compared to an untreated check treatment. Insecticides were applied with a CO2 backpack sprayer using a 4-nozzle boom with 11004 nozzles at 30 PSI and 35 gal/acre.

Onions in each plot were evaluated subjectively for severity of symptoms of IYSV on August 15. Fifteen consecutive plants in one of the middle 2 rows of each plot were rated on a scale of 0 to 5 of increasing severity of symptoms, where the rating was 0 if there were no symptoms, 1 if 1-25 percent of foliage was diseased, 2 if 26-50 percent of foliage was diseased, 3 if 51-75 percent of foliage was diseased, 4 if 76-99 percent of foliage was diseased, and 5 if 100 percent of foliage was diseased. The onions were lifted on September 13 to field cure. Onions from the middle two double rows in each plot were topped by hand and bagged on September 24. The onions from each plot were graded on October 19. During grading, bulbs were separated according to quality: bulbs without blemishes (No. 1s), split bulbs (No. 2s), neck rot (bulbs infected with the fungus Botrytis allii in the neck or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold (bulbs infected with the fungus Aspergillus niger). The No. 1 bulbs were graded according to diameter: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches). Bulb counts per 50 lb of supercolossal onions were determined for each plot of every variety by weighing and counting all supercolossal bulbs during grading. Marketable yield consisted of No. 1 bulbs larger than 2¼ inches.

Results and Discussion Fifteen insecticide rotations plus an untreated control were evaluated for their effectiveness in controlling thrips and IYSV. Thrips populations and onion bulb yield varied significantly between treatments, suggesting that thrips were a limiting factor. Thrips populations reached an average of one thrips per plant on May 21 and peaked in late June and early July (Table 3). For the season and at the peak thrips counts, all insecticide sequences resulted in lower average number of thrips per plant than the untreated check treatment. Sequences that had Movento® in the first two applications had thrips populations reaching a peak later in the season than sequences with Movento applied later or that did not include Movento (Figs. 1 and 2). Sequences that included applications of Movento were among those that had the lowest average number of thrips per plant for the season and at the peak. The two sequences that did not include Movento were among those with the highest average number of thrips per plant for the season and at the peak.

Treatments 8, 13, 14, 15, and 16 were among those with the highest marketable yield and yield of bulbs larger than 4 inches in diameter (Table 4). Treatments 1 and 5 were among those with the lowest marketable yield and yield of bulbs larger than 4 inches in diameter. The severity of IYSV symptoms in 2012 was low, with no significant differences between treatments.


Movento and Agri-mek® were effective in early season thrips control. Lannate® and Radiant® were effective in mid- to late season thrips control. Other materials (Aza-Direct®, M-Pede®) may help early in the season.


Table 1. Conventional insecticide rotation sequence treatments tested for efficacy against onion thrips. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Date 5/30/2012 6/5/2012 6/12/2012 6/19/2012 6/26/20122 7/3/2012 7/12/2012 7/19/2012

Treatment 1st 2nd 3rd 4th 5th 6th 7th 8th

1 Control - - - - - - -

2 Movento Movento Lannate Lannate Radiant Radiant Lannate Lannate

3 M-Pede + Aza-Direct M-Pede + Aza-Direct Movento Movento Radiant Radiant Lannate Lannate

4 M-Pede + Movento M-Pede + Aza-Direct M-Pede + Aza-Direct Aza-Direct + Radiant Lannate Lannate Lannate Lannate

5 Radiant + M-Pede Radiant + M-Pede Movento Radiant Radiant Lannate Lannate Lannate

6 Agri-Mek Agri-Mek Movento Movento Radiant Radiant Lannate Lannate

7 Movento Movento Agri-mek Agri-Mek Radiant Radiant Lannate Lannate

8 Radiant + M-Pede Radiant Movento Movento Lannate Lannate Lannate Radiant

9 Movento Movento Radiant Radiant Lannate Lannate Lannate Radiant

10 Radiant Cyazypyr Lannate Radiant Cyazypyr Lannate Radiant Cyazypyr

11 Radiant Radiant Cyazypyr Cyazypyr Lannate Lannate Radiant Radiant

12 Radiant Radiant Movento Movento Lannate Lannate Radiant Radiant

13 Cyazypyr Cyazypyr Movento Movento Lannate Lannate Radiant Radiant

14 Movento Movento Cyazypyr Cyazypyr Lannate Lannate Radiant Radiant

15 Movento Movento Lannate Lannate Cyazypyr Cyazypyr Radiant Radiant

16 Movento Movento Lannate Lannate Radiant Radiant Cyazypyr Cyazypyr

Table 2. Characteristics of insecticides tested in 15 treatments for efficacy against onion thrips. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Product Rate Adjuvant Active Ingredient Mode of Action Group

Agrimek 3 fl oz Ballast 1.5 oz/100 gal; Preference 0.25% v/v Abamectin 6

Aza-Direct 12 fl oz - Azadirachtin unknown

Cyazypyr 13.5 fl oz Ballast 1.5-2 oz/100 gal Cyantraniliprole 28

Lannate 3 pt Preference 0.25% v/v Methomyl 1A

M-Pede 5.6 pt - Potassium salts of fatty acides unknown

Movento 5 fl oz Ballast 1.5-2 oz/100 gal; MSO Destiny 2.8 pt Spirotetramat 23

Radiant 8 fl oz Dyne-Amic 0.7 pt Spinetoram 5

Table 3. Average number of thrips per onion plant by sampling date in response to 15 insecticide treatments and an untreated check treatment (1). First insecticide application was made May 30. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Treatment 14 May 21 May 29 May 4 Jun 11 Jun 18 Jun 25 Jun 2 Jul 9 Jul 16 Jul 23 Jul 30 Jul 6 Aug 13 Aug 20 Aug Avg 1 0.3 0.7 4.4 7.6 12.8 25.1 33.4 28.9 34.7 25.2 11.8 9.1 6.4 3.9 3.3 14.1 2 0.3 0.5 4.1 7.0 8.0 4.3 6.6 5.9 9.6 15.2 15.2 12.2 7.3 3.9 3.9 6.9 3 0.4 0.6 3.6 8.4 12.6 18.8 13.9 5.8 4.1 5.7 8.9 14.1 8.0 4.9 3.9 7.6 4 0.3 0.7 4.5 5.8 7.3 2.8 4.8 8.4 11.9 22.1 16.3 13.7 7.7 5.8 4.1 7.7 5 0.4 0.8 3.3 6.3 7.2 17.6 6.1 8.1 5.5 15.4 13.0 17.0 5.8 5.0 4.6 7.7 6 0.3 0.5 3.9 11.7 11.1 20.9 11.3 6.7 4.7 5.6 8.5 13.3 7.0 6.2 3.8 7.7 7 0.4 1.2 4.3 8.0 9.7 5.4 6.8 4.2 4.3 14.8 16.6 18.2 7.5 4.5 3.5 7.3 8 0.4 1.1 5.1 7.8 7.8 17.2 8.9 7.5 7.7 7.1 6.6 9.9 7.6 4.4 3.8 7.0 9 0.3 0.6 3.0 7.2 6.1 2.9 4.7 3.9 7.8 17.7 12.1 11.8 5.9 4.9 3.7 6.2

10 0.4 1.4 6.3 8.5 10.0 5.8 10.9 20.3 18.7 14.7 9.9 15.6 7.5 5.5 3.9 9.3 11 0.3 1.0 4.7 7.2 11.1 16.2 33.3 20.4 12.7 15.4 8.1 11.5 7.4 5.8 3.3 10.6 12 0.4 1.1 6.0 9.4 9.3 17.6 19.6 7.3 10.7 9.0 6.3 8.0 6.0 3.9 3.9 7.9 13 0.4 0.7 5.7 9.0 12.6 20.9 12.9 10.6 8.8 3.8 7.1 11.1 5.5 4.1 2.5 7.7 14 0.3 1.0 4.2 5.4 8.5 4.9 8.9 4.8 8.4 17.2 9.2 10.9 6.6 5.0 3.4 6.6 15 0.4 0.8 2.8 6.2 7.5 3.5 5.1 6.9 13.4 8.8 5.9 9.7 5.6 5.2 2.9 5.6 16 0.6 0.9 4.4 7.0 8.4 3.9 5.5 2.7 5.1 13.0 13.2 9.5 5.4 4.4 3.5 5.8

Avg 0.4 0.8 4.4 7.6 9.4 11.7 12.0 9.5 10.5 13.2 10.5 12.2 6.7 4.8 3.6 7.9 LSD (0.05) NS NS NS 2.5 NS 8.1 9.5 4.5 7.2 7.2 4.9 5.4 NS NS NS 2.5

Table 4. Onion yield and iris yellow spot virus (IYSV) symptom severity in response to 15 insecticide rotation treatments and an untreated check treatment (1). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Marketable yield by grade

Bulb counts >4¼ in

Treatment Total yield Total >4 in >4¼ in 4-4¼ in 3-4 in 2¼-3 in No. 2s Small Total rot IYSV --------------------------------------------- cwt/acre -------------------------------------------- % of total yield #/50 lb 0-5*

1 1059.7 1050.7 440.3 63.1 377.2 588.1 22.3 0.0 6.0 0.27 31.3 0.9 2 1161.0 1152.3 688.5 124.5 564.0 445.4 18.4 0.0 5.3 0.28 30.7 1.1 3 1195.4 1189.5 742.4 186.1 556.3 432.8 14.4 0.0 3.6 0.18 31.2 1.0 4 1170.4 1160.6 704.1 170.5 533.6 437.7 18.8 0.0 8.3 0.13 31.4 1.1 5 1098.9 1090.1 651.0 109.2 541.8 422.8 16.3 0.0 5.4 0.31 30.7 1.1 6 1161.1 1156.6 735.6 146.5 589.1 409.6 11.4 0.0 2.9 0.14 29.9 1.0 7 1191.2 1177.7 759.6 211.2 548.4 397.9 20.2 2.2 7.2 0.32 30.8 1.0 8 1222.2 1215.9 795.2 234.2 561.0 404.2 16.5 0.0 4.6 0.15 30.3 1.1 9 1181.3 1172.7 757.9 209.1 548.9 398.4 16.4 0.0 6.0 0.26 30.1 1.0 10 1206.3 1193.0 726.5 168.0 558.5 448.5 18.1 0.0 3.3 0.82 29.8 0.9 11 1156.2 1144.3 691.7 137.3 554.3 436.4 16.3 0.0 3.6 0.73 30.0 1.0 12 1184.8 1169.8 758.5 207.0 551.5 392.0 19.4 0.0 5.5 0.81 29.1 1.0 13 1309.1 1300.8 830.8 202.5 628.2 451.9 18.2 0.0 3.4 0.37 30.8 0.9 14 1230.4 1221.4 836.9 228.5 608.4 366.0 18.6 0.0 5.3 0.30 30.8 1.1 15 1229.9 1224.2 846.0 244.5 601.5 368.3 9.8 0.0 3.3 0.20 31.2 1.0 16 1276.7 1259.7 814.2 261.5 552.7 432.4 13.2 0.0 5.5 0.90 29.8 1.0

average 1189.7 1180.0 736.2 181.5 554.7 427.0 16.8 0.1 4.9 0.39 30.5 1.0 LSD (0.05) 50.2 52.8 274.2 15.6 258.6 NS NS NS NS 0.5 NS NS

* IYSV: 0 = no symptoms, 1 = 1-25% of foliage diseased, 2 = 26-50% of foliage diseased, 3 = 51-75% of foliage diseased, 4 = 76-99% of foliage diseased, and 5 = 100% of foliage diseased.

Figure 1. Average number of thrips per plant over time for insecticide rotations with Movento in the first two applications and an untreated check. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 2. Average number of thrips per plant over time for insecticide rotations without Movento in the first two applications, 2 rotations with no Movento (Trts 10 and 11), and an untreated check. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


ALTERNATIVE METHODS FOR THRIPS CONTROL IN ONIONS, 2012 Clinton C. Shock, Erik B. G. Feibert, Kenzie J. Barlow, Ashley L. Rock, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR

Eric Jemmett, Jemmett Consulting and Research Farm, Parma, ID

Stuart Reitz, Malheur County Extension, Ontario, OR

Introduction Onion thrips and the iris yellow spot virus (IYSV) that these thrips can transmit are major production limiting factors in the Treasure Valley. There are about 20,000 acres of onions produced within a 50-mile radius of Ontario, Oregon. This high concentration of onions makes for unique production challenges, especially for onion thrips and IYSV management. Thrips can rapidly develop resistance to insecticides, and new insecticides may rapidly lose their effectiveness. Therefore, it is important to develop alternative management methods as part of an overall Integrated Pest Management (IPM) program. A field experiment was conducted to evaluate five different alternative control programs for thrips management.

Materials and Methods Onions were grown on an Owyhee silt loam with a pH of 7.7 and 1.7 percent organic matter, previously planted to wheat. In the fall of 2011, the wheat stubble was shredded and the field was irrigated. Based on a soil analysis, 100 lb of phosphorus/acre, 200 lbs of sulfur/acre, 1,000 lbs of gypsum/acre, and 1 lb of boron/acre were broadcast. The field was then disked, moldboard plowed, and groundhogged. On September 25, the field was fumigated with Vapam® at 15 gal/acre and bedded at 22 inches.

Onion seed (‘Vaquero’; Nunhems, Parma, ID) was planted on March 13 in double rows, spaced 3 inches apart using 150,000 seeds/acre. Each double row was planted on beds spaced 22 inches apart. Planting was done with a Beck planter. Onions were grown under drip irrigation. Drip tape (Toro Aqua-Traxx, Toro Co., El Cajon, CA) with emitters spaced 12 inches apart and an emitter flow rate of 0.22 gal/minute/100 ft was laid 2-4 inches deep between 2 onion beds at the time of planting. The distance between the tape and the center of each bed was 11 inches. The water application rate was 0.06 inch/hour. Immediately after planting, Lorsban® 15G insecticide was banded at 3.7 oz/1,000 ft of row (0.82 lbs ai/acre), and the soil surface was rolled.

The field was irrigated as necessary to maintain soil water tension at 20 cb at 8-inch depth. Soil water tension was monitored by six granular matrix sensors (Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside, CA) centered at 8-inch depth below the onion row. The sensors were automatically read three times a day with an AM-400 meter (Mike Hansen Co., East Wenatchee, WA).

Alternative Methods for Thrips Control in Onions, 2012 70

Onion emergence started on April 12. Weekly thrips counts were made, starting on May 14. Thrips counts were made by counting the number of thrips on 15 consecutive plants in one of the middle 2 rows of each plot. Each treatment plot was 4 double rows wide by 27 ft long.

Treatments were applied weekly beginning May 30, according to the schedule and rates listed in Tables 1 and 2. Five alternative treatments were compared with an untreated control and a standard insecticide program. Straw mulch has been shown to enhance populations of some beneficial insects in onion. Mycotrol® O is an insecticide whose active ingredient is the naturally occurring fungus, Beauveria bassiana. Powdered kaolinite clay (Surround®, Tessenderlo Kerley, Inc., Phoenix, AZ) has been found to control some insects by acting as a repellant and physical barrier to insect movement. Diatomaceous earth is powdered sedimentary rock formed from fossilized diatoms. Diatomaceous earth may kill insects through abrasion and dehydration. The insecticides and Mycotrol O were applied with a CO2 backpack sprayer using a 4-nozzle boom with 8010 nozzles at 40 PSI and 100 gal/acre.

Onions in each plot were evaluated subjectively for severity of symptoms of IYSV on August 15. Fifteen consecutive plants in one of the middle 2 rows of each plot were rated on a scale of 0 to 5 of increasing severity of symptoms, where the rating was 0 if there were no symptoms, 1 if 1-25 percent of foliage was diseased, 2 if 26-50 percent of foliage was diseased, 3 if 51-75 percent of foliage was diseased, 4 if 76-99 percent of foliage was diseased, and 5 if 100 percent of foliage was diseased. The onions were lifted on September 13 to field cure. Onions from the middle two double rows in each plot were topped by hand and bagged on September 24. The onions from each plot were graded on October 19. During grading, bulbs were separated according to quality: bulbs without blemishes (No. 1s), split bulbs (No. 2s), neck rot (bulbs infected with the fungus Botrytis allii in the neck or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold (bulbs infected with the fungus Aspergillus niger). The No. 1 bulbs were graded according to diameter: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches). Bulb counts per 50 lb of supercolossal onions were determined for each plot of every variety by weighing and counting all supercolossal bulbs during grading. Marketable yield consisted of No. 1 bulbs larger than 2¼ inches.

Results and Discussion Thrips populations reached an average of one thrips per plant on May 21 and peaked in late June and early July (Table 3). For the season and at the peak thrips counts, there was no significant difference in average number of thrips per plant between the untreated check (treatment 1) and any of the alternative control treatments (3-7). The standard insecticide (treatment 2) had lower average number of thrips per plant for the season and at the peak thrips counts than the untreated check and the alternative treatments (Fig. 1).

Treatment 2 (standard insecticide treatment) had higher total and marketable yield than the other treatments (Table 4). None of the other treatments differed in total and marketable yield from the untreated check at a 95 percent probability level (LSD 0.05). At a 90 percent probability level (LSD 0.10), treatment 6 (mulch, Mycotrol O, and diatomaceous earth) had greater total,


marketable, and jumbo yield and lower peak thrips counts than the untreated check. Treatment 2 had the highest yield of bulbs larger than 4 inches in diameter followed by treatment 3. There was no difference in yield of bulbs larger than 4 inches in diameter between the other treatments and the untreated check. The severity of IYSV symptoms in 2012 was low, with no significant differences between treatments.

Figure 1. Average number of thrips per onion plant over time for alternative control treatments, a standard insecticide treatment, and an untreated check. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Table 1. Alternative thrips management treatments tested for efficacy against onion thrips. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Date 5/30/2012 6/5/2012 6/12/2012 6/19/2012 6/26/20122 7/3/2012 7/12/2012 7/19/2012

Treatment 1st 2nd 3rd 4th 5th 6th 7th 8th

1 Untreated control - - -

2 Movento Movento Lannate Lannate Radiant Radiant Lannate Lannate

3

Mulch, Mycotrol O, Kaolin, Diatomaceous Earth

Mycotrol O, Diatomaceous Earth



Mycotrol O, Kaolin, Diatomaceous Earth

4









5 Mulch, Kaolin, Diatomaceous Earth

Diatomaceous Earth

Diatomaceous Earth

Kaolin, Diatomaceous Earth

Diatomaceous Earth

Diatomaceous Earth

Kaolin, Diatomaceous Earth

Diatomaceous Earth

6

Mulch, Mycotrol O, Diatomaceous Earth








7 Mulch, Mycotrol O, Kaolin

Mycotrol O, Kaolin

Mycotrol O, Kaolin

Mycotrol O, Kaolin

Mycotrol O, Kaolin

Mycotrol O, Kaolin

Mycotrol O, Kaolin

Mycotrol O, Kaolin

Table 2. Characteristics of products tested in six treatments for efficacy against onion thrips. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Product Rate Adjuvant Active Ingredient Mode of Action Group

Mycotrol Oa 1 qt/100 gal Beauveria bassiana GHA (fungal pathogen)

Surrounda 50 lbs/acre Kaolin (reflective, physical barrier)

Diatomaceous eartha none (abrasion)

Straw mulch 1000 lbs/acre none (favors predators)

Lannate 3 pt/acre Preference 0.25% v/v Methomyl 1A

Movento 5 fl oz/acre Ballast 1.5-2 oz/100 gal; MSO Destiny 2.8 pt Spirotretramat 23

Radiant 8 fl oz/acre Dyne-Amic 0.7 pt Spinetoram 5

aMycotrol O, Surround, and Diatomaceous earth are OMRI-approved products for organic production.

Table 3. Average number of thrips per onion plant by sampling date in response to five alternative thrips control treatments (3-7) compared to a standard insecticide treatment (2), and an untreated check (1). First insecticide application was made May 30. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Trt 14 May 21 May 29 May 4 Jun 11 Jun 18 Jun 25 Jun 2 Jul 9 Jul 16 Jul 23 Jul 30 Jul 6 Aug 13 Aug 20 Aug Avg 1 0.1 0.4 4.0 10.2 16.1 31.4 48.8 30.9 40.4 28.9 21.8 9.1 5.9 4.1 2.7 17.0 2 0.1 0.5 3.4 5.3 12.6 6.1 9.7 6.0 14.8 23.4 18.3 17.5 8.9 4.1 3.3 8.9 3 0.2 0.6 1.9 7.2 10.2 26.3 43.6 33.4 31.6 27.3 23.1 11.2 6.6 4.0 2.9 15.3 4 0.3 0.9 5.2 9.1 14.3 21.9 40.1 33.2 39.4 28.0 21.1 13.1 6.1 5.1 3.8 16.1 5 0.2 0.5 5.5 9.3 12.8 30.3 45.8 32.2 36.9 29.8 20.9 13.6 6.8 4.8 3.0 16.8 6 0.1 0.2 2.9 6.4 13.8 20.7 38.0 36.1 34.7 26.6 21.7 14.0 6.0 3.7 2.7 15.2 7 0.3 0.3 3.1 10.1 12.5 26.6 47.1 41.1 38.7 38.9 26.8 11.2 4.5 5.1 3.0 18.0

Avg 0.2 0.5 3.7 8.2 13.2 23.3 39.0 30.4 33.8 29.0 22.0 12.8 6.4 4.4 3.0 15.3 LSD (0.05) NS NS NS NS NS 11.6 12.3 13.2 8.3 6.7 NS NS 1.6 NS NS 2.4

Table 4. Onion yield and iris yellow spot virus (IYSV) symptom severity in response to five alternative thrips control treatments, a standard control treatment (2), and an untreated check treatment (1). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Marketable yield by grade

Bulb counts >4¼ in

Treatment Total yield Total >4 in >4¼ in 4-4¼ in 3-4 in 2¼-3 in No. 2s Small Total rot IYSV --------------------------------------------- cwt/acre ----------------------------------------------- % of total yield #/50 lb 0 - 5

1 961.4 954.5 362.0 37.7 324.3 565.0 27.6 0.0 6.8 0.0 31.0 1.1 2 1125.4 1116.7 565.0 92.4 472.7 533.8 17.9 0.0 8.8 0.0 32.3 1.1 3 969.5 961.3 450.8 42.4 408.4 492.0 18.5 0.0 6.4 0.2 34.1 1.1 4 994.1 985.7 293.6 14.0 279.6 656.4 35.6 0.0 7.1 0.1 31.2 1.1 5 960.6 951.0 363.4 37.7 325.7 568.3 19.3 0.0 6.5 0.3 32.0 1.1 6 1032.8 1026.2 376.4 28.4 348.0 629.0 20.8 0.0 4.1 0.3 30.6 1.1 7 999.1 990.2 224.1 5.3 218.8 742.6 23.5 0.0 4.6 0.4 32.8 1.0

Average 1006.1 997.9 376.5 36.8 339.6 598.2 23.3 0.0 6.3 0.2 32.0 1.1 LSD (0.05) 73.0 71.9 64.6 37.0 75.5 68.1 NS NS NS NS NS NS LSD (0.10) 59.7 58.8 52.8 30.2 61.8 55.7 NS NS NS NS NS NS

POST-EMERGENCE HERBICIDE COMBINATIONS FOR WEED CONTROL IN DIRECT-SEEDED ONION Joel Felix and Joey Ishida, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Introduction

Weed control in direct-seeded onion is essential in order to realize acceptable bulb size and minimize yield losses from weed competition. Onions are vulnerable to weed competition because of the slow early development and lack of a complete canopy cover to shade weeds. Information is needed on the response of onions to tank mixes that include recently registered herbicides (e.g., Starane® Ultra) and nonregistered products (e.g., Reflex®) with the local onion production grower standard of GoalTender® and Buctril®. The weed control research program at the Malheur Experiment Station endeavors to evaluate new herbicides that come on the market and determine their usefulness for weed control in direct-seeded onions grown under local production practices. The objective of this study was to evaluate treatment combinations for weed control efficacy and direct-seeded onion tolerance under furrow-irrigation conditions. Materials and Methods A field study was established at the Malheur Experiment Station, Ontario, Oregon in 2012 to evaluate onion response to various herbicide combinations applied prior to or after onion emergence. The herbicide Sharpen® (saflufenacil) was applied prior to onion emergence at 0.71 lb ai/acre, while Dual II Magnum® (S-metolachlor) was applied at 15.3 or 20.3 oz ai/acre. Nortron® was applied prior to onion emergence at 10 oz ai/acre, while Reflex was applied at 4 oz ai/acre. The complete list of treatments is contained in Tables 1-3. The wheat stubble was flailed and the field was plowed during fall 2011. Urea fertilizer was applied during fall 2011 to provide 100, 200, and 1 lb/acre of phosphate, sulfur, and boron, respectively. The field was then plowed, disked, and 22-inch-wide beds were formed. The beds were harrowed and reshaped on March 19, 2012. Onion variety ‘Vaquero’ was planted on March 27 in double rows spaced 3 inches apart and 4-inch seed spacing within each row on beds spaced 22 inches apart. The study was a randomized complete block design with four replications. Individual plots measured 7.33 ft (4 rows wide) and 27 ft long. Lorsban 15G® (chlorpyrifos at 0.101 lb ai/acre) was banded at 3.7 oz/1,000 ft of row over the top of the onion rows on April 5 and the soil surface was rolled. Preemergence herbicide treatments were applied on April 3 using a small plot backpack sprayer. Treatment rates for the evaluated herbicides are contained in Table 1. All postemergence treatments were applied May 15, 2012 when onion plants were at the two-leaf stage. All plots (except the untreated control) were sprayed again with GoalTender® and Buctril® at the rate of 0.5 pt/acre, equivalent to oxyfluorfen at 2 oz ai/acre and bromoxynil at 2 oz ai/acre, respectively on June 4, 2012. Plants were also sprayed (except the untreated control) with Poast®

Post-Emergence Herbicide Combinations for Weed Control in Direct-Seeded Onion 76

(sethoxydim) at 0.287 lb ai/acre on June 4 to control grassy weeds. The first furrow irrigation was applied on May 12 and lasted 24 hours to supply about 4 inches of water (including runoff). All subsequent irrigations (16 times from May 21 to August 30, 2012) lasted the same duration and delivered the same amount of water. Plants were sidedressed with urea fertilizer on June 1 to supply nitrogen at 200 lb/acre. Onion plants were sprayed with Movento® (spirotetramat) at 0.078 lb ai/acre tank-mixed with Prime Oil (crop oil concentrate) at 1.57 lb ai/acre on June 11 and 18 to control thrips. Plants were aerially sprayed for thrips control on June 25 using Radiant® (spinetoram) at 0.078 lb ai/acre tank-mixed with a crop oil concentrate. Subsequent aerial sprays for thrips control were on July 14, 21, and August 3 and 11 using Lannate® at 0.9 lb ai/acre. Plants were visually evaluated for weed control and crop injury on May 12 and June 12 based on 0 to 100 percent; where 0 percent = no weed control or crop injury and 100 percent = complete weed control or complete crop kill. Plant tops were flailed on September 7 and bulbs lifted on September 10, 2012. Bulbs were hand-harvested from the two center rows on September 12 and graded on September 19, 2012. Bulbs were graded for quality and yield on September 23 based on USDA standards. The data were subjected to analysis of variance and the treatment means were compared using LSD at 0.05 percent level of confidence. Results and Discussion Preemergence application of Sharpen at 0.71 lb ai/acre injured onion 59 percent compared to the hand-weeded control and more than any other herbicide (Table 1). Onion injury was 10 and 8 percent when Dual II Magnum was applied at 15.2 and 20.3 oz ai/acre, respectively. Injury from Nortron at 10 oz ai/acre applied prior to onion planting caused only 3 percent injury. Reflex applied at 4 oz ai/acre when onions were at the two-leaf stage caused only 8 percent injury. GoalTender alone applied at the two-leaf stage did not cause any visible injury. Injury from GoalTender tank-mixed with Buctril caused injury ranging from 3 to 8 percent. Mid-season control for common lambsquarters varied by the herbicide treatment and ranged from 70 to 96 percent. Control was generally reduced when herbicides other than Prowl® H2O were used prior to onion emergence. Preemergence application of Sharpen at 0.71 oz ai/acre, Nortron at 10 oz ai/acre, and Dual II Magnum at 15.3 and 20.3 oz ai/acre provided 19, 10, 20, and 25 percent less common lambsquarters control than the grower standard of Prowl H2O (Table 1). All herbicide treatments provided complete control for hairy nightshade and barnyardgrass. Redroot pigweed control was over 96 percent except when Sharpen was used preemergence. Reduced early season control of common lambsquarters control with the experimental products resulted in bigger weeds that were hard to control with GoalTender and Buctril applied when onions were at the two-leaf stage. The number of onion bulbs varied across herbicide treatments (Table 2). The number of small bulbs ranged from 593 to 8,012/acre across herbicide treatments. Medium-size bulbs ranged from 3,265 to 12,759 bulbs/acre, while jumbo bulbs varied from 54,302 to 78,930/acre. The number of jumbo and colossal bulbs was reduced when Sharpen at 0.71 lb ai/acre was applied prior to onion emergence compared to the rest of herbicide treatments. Sharpen also reduced the number of U.S. No. 1 bulbs compared to the other herbicides.


Yield for the small bulb category was similar across herbicide treatments and highest for the untreated control (Table 3). Medium bulb category ranged from 11.5 to 47.3 cwt/acre across herbicide treatments. Yield for colossal bulbs ranged from 175.7 cwt/acre to 541 cwt/acre. The U.S. No.1 onion yield was reduced when Sharpen was applied prior to onion emergence. Application of Nortron prior to onion emergence did not reduce onion yield. Yield was low when Dual II Magnum was applied prior to onion emergence, but statistically similar to the grower standard. These results indicated that application of Starane Ultra at 1.95 oz ai/acre tank-mixed with Buctril at 2 oz ai/acre did not adversely affect onion yield. More studies are needed to evaluate Reflex and Dual II Magnum for weed control in direct-seeded onion. Therefore, this study will be repeated in 2013 to further evaluate these herbicide combinations further.


Table 1. Weed control on June 12 in direct-seeded dry bulb onion treated with various herbicides at the Malheur Experiment Station at Ontario, OR, 2012.

Weed control

Treatment Rate Timinga Crop injury Common lambsquarters

Hairy nightshade

Redroot pigweed Barnyardgrass

oz ai/acre --------------------------------------------- % ------------------------------------------------- Untreated 0 0 0 0 0 Prowl H2O (Grower std) 15.2 Pre-emerg 0 95 99 99 99 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emerg 3 86 100 99 100 Starane Ultra 1.95 2-leaf Prowl H2O 15.20 Pre-emerg 8 96 100 99 100 Starane Ultra 1.95 2-leaf Buctril 2.00 2-leaf Prowl H2O 15.2 Pre-emerg 0 90 100 99 100 GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emerg 3 98 100 100 100 Starane Ultra 1.95 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emerg 8 83 100 96 100 Reflex 4.00 2-leaf Sharpen 0.71 Pre-emerg 59 76 100 93 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Nortron 10.00 Pre-emerg 3 85 100 96 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Dual II Magnum 15.3 Pre-emerg 10 75 100 96 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Dual II Magnum 20.3 Pre-emerg 8 70 100 98 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Handweeded 0 100 100 100 100 LSD (P = 0.05) 8 13 1 5 1

a Herbicide application timing; A = preplant incorporated; B = preemergence; C = onion at 1 leaf; D = onion at 2 leaf stage.


Table 2. Number of onion bulbs in response to various herbicides applied on direct-seeded onion at the Malheur Experiment Station at Ontario, OR, 2012.

Application Number of onion bulbsa Treatment Rate timing Small Medium Jumbo Colossal Supercolossal U.S. No. 1 Total number oz ai/acre -------------------------------------------------------- no./acre -------------------------------------------------------- Untreated 38,872 7,418 297 0 0 7,715 46,587 Prowl H2O (Grower std) 15.2 Pre-emergence 593 3,561 57,566 32,937 5,935 99,998 100,592 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emergence 2,077 6,825 63,500 34,717 2,967 108,010 110,087 Starane Ultra 1.95 2-leaf Prowl H2O 15.20 Pre-emergence 1,780 6,231 54,302 36,201 5,935 102,669 104,449 Starane Ultra 1.95 2-leaf Buctril 2.00 2-leaf Prowl H2O 15.2 Pre-emergence 2,671 7,122 77,447 26,112 3,561 114,241 116,912 GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emergence 1,780 3,264 65,281 42,136 5,935 116,615 118,395 Starane Ultra 1.95 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emergence 2,697 5,638 68,545 22,255 1,780 98,218 101,185 Reflex 4.00 2-leaf Sharpen 0.71 Pre-emergence 8,012 9,792 38,872 14,243 1,780 64,687 72,699 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Nortron 10.00 Pre-emergence 2,967 5,638 59,346 29,376 5,935 100,295 103,262 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Dual II Magnum 15.3 Pre-emergence 3,561 10,089 78,930 18,397 2,077 109,493 113,054 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Dual II Magnum 20.3 Pre-emergence 5,044 12,759 62,313 21,667 2,967 99,701 104,746 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Handweeded 890 4,451 62,017 41,839 9,495 117,802 118,692 LSD (P = 0.05) 7,456 7,039 18,008 13,286 5,571 18503 19,964

a Onion were graded to size as follows: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches); and U.S. No. 1 was composed of medium through colossal.

Table 3. Onion yield in response to various herbicides applied on direct-seeded onion at the Malheur Experiment Station at Ontario, OR, 2012.

Application Onion yielda Treatment Rate timing Small Medium Jumbo Colossal Supercolossal U.S. No. 1 Total number oz ai/acre --------------------------------------------------- cwt/acre -------------------------------------------------------- Untreated 28.7 15.3 1.4 0.0 0.0 16.7 45.4 Prowl H2O (Grower std) 15.2 Pre-emergence 0.8 14.1 501.0 417.8 100.6 1,033.5 1,034.3 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emergence 4.7 26.7 556.5 442.2 52.5 1,078.0 1,082.7 Starane Ultra 1.95 2-leaf Prowl H2O 15.20 Pre-emergence 4.8 23.6 463.0 461.6 102.2 1,050.3 1,055.1 Starane Ultra 1.95 2-leaf Buctril 2.00 2-leaf Prowl H2O 15.2 Pre-emergence 6.6 28.8 672.6 320.1 59.7 1,081.0 1,087.7 GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emergence 4.7 11.5 587.2 541.7 99.4 1,239.9 1,244.5 Starane Ultra 1.95 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Pre-emergence 7.0 21.5 568.0 271.9 31.1 892.6 899.9 Reflex 4.00 2-leaf Sharpen 0.71 Pre-emergence 12.9 31.7 329.6 175.7 28.9 565.9 579.8 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Nortron 10.00 Pre-emergence 6.3 21.2 516.2 370.3 99.5 1,007.1 1,013.4 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Dual II Magnum 15.3 Pre-emergence 6.8 40.3 641.0 229.6 33.0 943.9 950.8 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Dual II Magnum 20.3 Pre-emergence 11.0 47.3 507.2 269.7 50.6 874.8 885.9 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Handweeded 2.2 18.3 545.8 528.6 153.4 1,246.0 1,248.2 LSD (P = 0.05) 12.7 23.7 152.2 172.4 90.6 874.8 210.8

a Onion were graded to size as follows: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches); and U.S. No. 1 was composed of medium through colossal.

EVALUATION OF SUSTAIN® ADJUVANT FOR IMPROVED HERBICIDE WEED EFFICACY IN DIRECT-SEEDED ONION Joel Felix and Joey Ishida, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Introduction Sustain® is a nonionic surfactant containing a specific pinolene polymer designed to improve product performance in the soil and plants. When applied to the soil, the resin-based polymer binds the herbicides on the soil surface to improve product performance. It is believed that the Sustain polymer is insoluble in water, hence the reason it helps to keep compounds from leaching or moving laterally. It does not provide complete suppression of lateral movement, but appears to keep more active ingredients of soil-applied herbicides in the target zone. In addition, Sustain is not rapidly degraded by microbes, and therefore, could enhance the activity for soil-applied herbicides. Sustain also improves the contact, wetting, and adhesion of pesticides on plant leaves. The objective of this study was to evaluate weed control efficacy for herbicides with and without Sustain in direct-seeded bulb onion.

Materials and Methods A field study was conducted in 2012 at the Malheur Experiment Station near Ontario, Oregon to evaluate weed control efficacy with various herbicides applied preemergence (PRE) or postemergence (POST) with and without Sustain on direct-seeded bulb onion. The wheat stubble was flailed and the field plowed during fall 2011. Urea fertilizer was applied during fall 2011 to provide 100, 200, and 1 lb/acre of phosphate, sulfur, and boron, respectively. The field was plowed, disked, and 22-inch-wide beds formed. The beds were harrowed and reshaped on March 19, 2012. Onion variety ‘Vaquero’ was planted on March 27 in double rows spaced 3 inches apart and 4-inch seed spacing within the row on beds spaced 22 inches apart.

Herbicide treatments were arranged in randomized complete block design with four replications. Individual plots measured 7.33 ft (4 beds wide) by 27 ft long. Lorsban® 15G (chlorpyrifos at 0.101 lb ai/acre) was banded at 3.7 oz/1,000 ft of row over the top of the onion rows on April 5 and the soil surface was rolled. Roundup® was applied at 22 fl oz/acre (glyphosate at 0.77 lb ae/acre) on April 22 to control emerged weeds prior to onion emergence. The first furrow irrigation was applied on May 12 and lasted 24 hours to supply about 4 inches of water (including overflow). All subsequent irrigations (12 times from June 10 to August 29, 2011) lasted the same duration and delivered the same amount of water. Herbicide treatments included Prowl® H2O (pendimethalin) at 0.98 lb ai/acre applied PRE on April 3 with and without Sustain at 1.04 lb ai/acre (Table 1). POST treatments were applied on

Evaluation of Sustain® Adjuvant for Improved Herbicide Weed Efficacy in Direct-Seeded Onion 82

May 15 when onions were at the two-leaf stage. A grower standard that included Prowl H2O at 0.98 lb ai/acre PRE followed by GoalTender® (oxyfluorfen) at 0.25 lb ai/acre POST and the nontreated control were also included. On June 4, onions (except the untreated control) were sprayed with Poast® (sethoxydim) at 0.287 lb ai/acre POST to control grassy weeds. All onions (except the untreated control) were sprayed again with GoalTender and Buctril® (bromoxynil) at the rates of 0.5 pt/acre each equivalent to oxyfluorfen at 2 oz ai/acre and bromoxynil at 2 oz ai/acre, respectively, on June 4, 2012. All herbicide treatments were applied using a CO2-pressurized backpack sprayer with a boom equipped with four 8002 EVS nozzles and calibrated to deliver 20 gal/acre at 35 PSI at 3 mph. The first furrow irrigation was applied on May 12 and lasted 24 hours to supply about 4 inches of water (including runoff). All subsequent irrigations (16 times from May 21 to August 30, 2012) were the same duration and delivered the same amount of water. Onion plants were sidedressed with urea fertilizer to supply 200 lb/acre of nitrogen on June 1. Onion plants were sprayed with Movento® (spirotetramat) at 0.078 lb ai/acre tank-mixed with Prime Oil (crop oil concentrate) at 1.57 lb ai/acre on June 11 and 18 to control thrips. Plants were aerially sprayed for thrips control on June 25 using Radiant® (spinetoram) at 0.078 lb ai/acre tank-mixed with a crop oil concentrate. Subsequent aerial sprays for thrips control were on July 14, 21, August 3 and 11 using Lannate® (methomyl) at 0.9 lb ai/acre. Plants were visually evaluated for weed control and crop injury on May 12 and June 12 based on 0 to 100 percent, where 0 percent = no weed control or crop injury and 100 percent = complete weed control or complete crop kill. Onion plant tops were flailed on September 7 and bulbs lifted on September 10, 2012. Bulbs were hand-harvested from the two center rows on September 12 and graded on September 19, 2012. The data were subjected to analysis of variance and treatment means were compared using LSD at 0.05 percent level of confidence.

Results There was no crop injury observed from any of the herbicide and Sustain treatments (Table 1). Evaluations on June 12 (61 days after treatment) indicated a similar level of weed control when Prowl H2O was applied with or without Sustain prior to onion emergence (Table 1). Application of Prowl H2O plus Sustain prior to onion emergence provided 88 percent control of common lambsquarters compared to 80 percent for Prowl H2O alone. Control for redroot pigweed, hairy nightshade, and barnyardgrass was also similar for Prowl H2O with and without Sustain. These results contrast with our findings in 2011 (Felix and Ishida 2012) when Prowl H2O plus Sustain improved common lambsquarters and redroot pigweed by 20 and 31 percent, respectively. It is possible that the differences in weed control between 2011 and 2012 could be attributed to variation in weather conditions between the years. The weather during 2011 was generally cool and wet compared to drier and warmer conditions in 2012. Tank-mixing GoalTender with Sustain improved common lambsquarters control by 5 percent compared to GoalTender alone (Table 1). Hairy nightshade and barnyardgrass control was similar across the treatments.

The yield for small onion (<2.25 inch diameter) was similar across herbicide treatment combination and highest for the untreated control (Table 2). Medium category (2¼-3 inch diameter) yield was similar across treatments and ranged from 11.2 to 29 cwt/acre. The jumbo category (3-4 inch diameter) yield ranged from 225.2 to 721.3 cwt/acre across herbicide


treatments. The yield for colossal bulbs (4-4¼ inch diameter) was higher in the Prowl H2O plus Sustain treatment (479.7 cwt/acre) compared to Prowl H2O alone (269.3 cwt/acre). However, the colossal yield was similar for treatments that were applied at the two-leaf stage with and without Sustain. Yield for the U.S. No. 1 bulbs was higher in the Prowl H2O plus Sustain (1,169.3 cwt/acre) compared to Prowl H2O alone (1,065.2 cwt/acre). The increase in U.S. No. 1 bulbs for the Prowl H2O plus Sustain was mainly influenced by the high yield in the jumbo category.

The results indicated that the application of Prowl H2O plus Sustain prior to onion emergence may improve some weed control compared to Prowl H2O alone. The results varied between 2 years, suggesting that the performance could be influenced by the weather. However, the improved weed control did not result in improved onion yield. The study will be repeated in 2013 to confirm these results.

References Felix, J., and J. Ishida. 2012. Evaluation of Sustain® adjuvant for improved herbicide weed efficacy in direct-seeded onion. Malheur Experiment Station Annual Report 2011, Ext/CrS 141:87-91.


Table 1. Weed control in onion on June 12 (70 days after treatment) with various herbicides applied with and without Sustain® at the Malheur Experiment Station, Ontario, OR, 2012.

Application Weed controla

Treatment Rate timingb Crop injury

Common lambsquarters

Hairy nightshade


lb ai/a --- % --- ------------------------------------- % -------------------------------------------- Untreated 0 0 0 b 0 c 0 b Prowl H2O 0.98 A 0 88 bc 98 a 76 b 100 a Sustain 1.04 A Prowl H2O 0.98 A 0 80 c 98 a 73 b 100 a Prowl H2O 0.98 A 0 93 ab 100 a 98 a 100 a GoalTender 0.25 B Sustain 1.04 B Prowl H2O 0.98 A 0 88 bc 100 a 93 a 100 a GoalTender 0.25 B Prowl H2O 0.98 A 0 96 a 100 a 99 a 100 a GoalTender 0.25 B Buctril 0.125 B Sustain 1.04 B Prowl H2O 0.98 A 0 93 ab 100 a 96 a 100 a GoalTender 0.25 B Buctril 0.125 B Prowl H2O 0.98 A 0 99 a 100 a 100 a 100 a Outlook 0.98 B Sustain 1.04 B Prowl H2O 0.98 A 0 98 a 100 a 99 a 100 a Dual Magnum 1.27 B Sustain 1.04 B Prowl H2O 0.98 A 0 91 ab 100 a 95 a 100 a GoalTender 0.25 B (grower standard) a Means within a column followed by the same letter are not significantly different according to LSD P = 0.05. b Application timing; A = preemergence (April 3, 2012), B = postemergence (May 15, 2012). All treatments (except for the untreated control) received an additional GoalTender plus Buctril application on June 4, 2012.


Table 2. Onion yield in response to different herbicides applied with and without Sustain® at the Malheur Experiment Station, Ontario, OR, 2012. Onion yielda Marketable yield grade Application Small Medium Jumbo Colossal S Colossal U.S. No.1 Total Treatment Rate timingb <2¼ in 2¼-3 in 3-4 in 4-4¼ in >4¼ in 2¼->4¼ in yield

lb ai/acre ------------------------------------- cwt/acre --------------------------------------------

Untreated 22.2 a 14.2 a 0.0 b 0.0 c 0.0 c 14.2 d 36.3 d Prowl H2O 0.98 A 5.8 b 15.5 a 592.2 a 479.7 a 81.6 abc 1,169.3 abc 1,175.2 abc Sustain 1.04 A Prowl H2O 0.98 A 3.9 b 23.9 a 721.3 a 269.3 b 50.9 bc 1,065.2 c 1,069.1 c Prowl H2O 0.98 A 4.9 b 26.9 a 646.5 a 413.2 ab 53.6 bc 1,140.2 abc 1,145.1 abc GoalTender 0.25 B Sustain 1.04 B Prowl H2O 0.98 A 5.6 b 29.0 a 544.9 a 464.7 a 80.4 abc 1,119.0 bc 1,124.7 bc GoalTender 0.25 B Prowl H2O 0.98 A 2.7 b 17.0 a 225.2 a 473.8 a 169.2 a 1,212.1 ab 1,214.8 ab GoalTender 0.25 B Buctril 0.125 B Sustain 1.04 B Prowl H2O 0.98 A 3.9 b 19.7 a 574.1 a 478.7 a 112.3 ab 1,184.8 abc 1,188.6 abc GoalTender 0.25 B Buctril 0.125 B Prowl H2O 0.98 A 3.9 b 11.2 a 609.7 a 521.4 a 117.6 ab 1,259.8 a 1,263.8 a Outlook 0.98 B Sustain 1.04 B Prowl H2O 0.98 A 9.1 b 19.5 a 545.2 a 499.2 a 94.1 abc 1,158.0 abc 1,167.0 abc Dual Magnum 1.27 B Sustain 1.04 B Prowl H2O 0.98 A 3.6 b 19.3 a 630.3 a 361.8 ab 88.8 abc 1,100.3 bc 1,103.9 bc GoalTender 0.25 B (grower standard)

a Means within a column followed by the same letter are not significantly different according to LSD P = 0.05. b Application timing; A = preemergence (April 3, 2012), B = postemergence (May 15, 2012). All treatments (except for the untreated control) received an additional GoalTender plus Buctril application on June 4, 2012.


EVALUATION OF ZIDUA® (PYROXASULFONE) AND WARRANT® (ACETOCHLOR) FOR WEED CONTROL IN DIRECT-SEEDED ONION Joel Felix and Joey Ishida, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Introduction

Specialty crops such as direct-seeded onions tend to have fewer herbicides that are registered for weed control than other agronomic crops. In fact most product labels include only major crops (wheat, corn, soybean, and cotton) when they are first registered. Therefore, new products must be evaluated on specialty crops for weed efficacy and crop response before they can be registered by the U.S. Environmental Protection Agency for use on specialty crops. Weed control in direct-seeded onion is essential in order to realize acceptable bulb size and yield. To that end, the weed program at the Malheur Experiment Station endeavors to evaluate new herbicides that come on the market and to determine their usefulness for weed control in direct-seeded onions grown under local production practices. The objective of this study was to evaluate Zidua® (pyroxasulfone) and Warrant® (acetochlor) for weed efficacy and tolerance by direct-seeded dry bulb onion grown under furrow irrigation. Materials and Methods A field study was established at the Malheur Experiment Station, Ontario, Oregon in 2012 to evaluate onion response to Zidua and Warrant herbicides. The study evaluated onion response and weed efficacy under furrow-irrigated conditions. The wheat stubble was flailed and the field was plowed during fall of 2011. Phosphorus (P2O5), sulfur, and boron were applied at 100, 200, and 1 lb/acre, respectively. The field was later plowed, groundhogged, fumigated using Metam VLR 42 percent at 15 gal/acre, and 22-inch wide beds were formed. The field was sprayed with glyphosate at 22 fl oz/acre (0.77 lb ae/acre) on March 19, 2012 to control emerged weeds. The beds were harrowed and reshaped on March 23, 2012. Onion variety ‘Vaquero’ was planted on March 27 in double rows spaced 3 inches apart with 4-inch seed spacing within the row on beds spaced 22 inches apart. The treatments were arranged in a randomized complete block design with four replications. Individual plots measured 7.33 ft (4 rows wide) and 27 ft long. Lorsban® 15G (chlorpyrifos at 0.101 lb ai/acre) was banded at 3.7 oz/1,000 ft of row over the top of the onion rows on April 5 and the soil surface was rolled. Preemergence herbicide treatments of Prowl® H2O, Zidua, and Warrant were applied on April 3 using a small plot backpack sprayer (Table 1). All postemergence treatments were applied May 15, 2012 when onion plants were at the two-leaf stage. All onions (except the untreated control) were sprayed again with GoalTender® and

Evaluation of Zidua® (pyroxasulfone) and Warrant® (Acetochlor) for weed control in Direct-Seeded Onion 87

Buctril® at 0.5 pt/acre, each equivalent to oxyfluorfen at 2 oz ai/acre and bromoxynil at 2 oz ai/acre, respectively on June 4, 2012. All onions (except the untreated control) were sprayed with Poast® (sethoxydim) at 0.287 lb ai/acre on June 4 to control grassy weeds. The first furrow irrigation was applied on May 12 and lasted 24 hours to supply about 4 inches of water (including runoff). All subsequent irrigations (16 times from May 21 to August 30, 2012) were the same duration and delivered the same amount of water per event. Plants were sidedressed with urea fertilizer to supply 200 lb/acre nitrogen on June 1. Onion plants were sprayed with Movento® (spirotetramat) at 0.078 lb ai/acre tankmixed with Prime Oil (crop oil concentrate) at 1.57 lb ai/acre on June 11 and 18 to control thrips. Plants were aerially sprayed for thrips control on June 25 using Radiant® (spinetoram) at 0.078 lb ai/acre tank-mixed with a crop oil concentrate. Subsequent aerial sprays for thrips control were on July 14, 21, and August 3 and 11 using Lannate® (methomyl) at 0.9 lb ai/acre. Plants were visually evaluated for weed control and crop injury on May 12 and June 12 based on 0 to 100 percent; where 0 percent = no weed control or crop injury and 100 percent = complete weed control or complete crop kill. Onion plant tops were flailed on September 7 and bulbs lifted on September 10, 2012. Bulbs were hand-harvested from the two center rows on September 12 and graded on September 19, 2012. The data were subjected to analysis of variance and treatment means were compared using LSD at 0.05 percent level of confidence. Results and Discussion Evaluations on May 12 indicated an average onion injury of 20 percent when Zidua and Warrant were applied prior to onion emergence. Evaluations on June 12 (after application of other herbicides at the two-leaf stage) indicated 14 to 16 percent and 10 to 14 percent injury for plants treated with Zidua and Warrant, respectively (Table 1). When Zidua was applied at the two-leaf stage in a tank-mixture with Buctril and GoalTender, the injury was only 6 to 8 percent compared to 5 percent for the grower standard of GoalTender plus Buctril. Similarly, the injury was reduced to 4 to 9 percent when Warrant application was delayed until onions were at the two-leaf stage. Mid-season control for common lambsquarters varied greatly for the different herbicide treatments ranging from 61 to 93 percent compared to 94 percent for the grower standard (Table 1). All herbicide treatments provided complete control for hairy nightshade and barnyardgrass. Control for redroot pigweed ranged from 95 to 100 percent across herbicide treatments. The number of onion bulbs varied across herbicide treatments (Table 2). Except for the untreated control, there was no difference in the number of small bulbs when Zidua and Warrant were applied prior to onion emergence or at the two-leaf stage. Small bulbs (<2¼ inch diameter) ranged from 1,187 to 2,671 bulbs/acre across herbicide treatments compared to 1,484 for the grower standard. Medium bulbs (2¼-3 inch diameter) ranged from 2,967 to 11,869 bulbs/acre across experimental herbicides compared to 3,857 for the grower standard. Jumbo bulbs (3-4 inch diameter) varied from 64,094 to 84,271/acre compared to 52,521 for the grower standard. Colossal bulbs (4-4¼ inch diameter) ranged from 21,661 to 40,355 bulbs/acre across herbicide treatments. Except for the untreated control, there was no difference in supercolossal bulbs (>4¼ inch diameter) across different herbicide treatments. Similar numbers of U.S. No. 1 onion bulbs were obtained for Zidua and Warrant applied pre- and postemergence and the grower standard.


Small onion yield was similar across different herbicides and highest for the untreated control (Table 3). Yield for the medium, colossal, and supercolossal categories was similar across herbicide treatments. However, when grouped to generate the U. S. No. 1 category (medium to supercolossal), Zidua applied prior to onion emergence at 1.7 lb ai/acre and Warrant at 16 oz ai/acre resulted in reduced yield compared to the grower standard. It is likely weather conditions may have contributed to the results obtained in 2012. The weather was generally dry during spring when Zidua and Warrant were applied prior to onion emergence. It is not clear why Warrant at 16 oz ai/acre reduced the yield, but not at the 18 oz ai/acre rate. These results indicated that Zidua and Warrant may have a potential to be used for weed control in direct-seeded dry bulb onions. We will continue to evaluate these two products to generate more data on crop safety and weed efficacy. Acknowledgements This project was funded by the Idaho-Eastern Oregon Onion Committee in cooperation with Oregon State University, Malheur Experiment Station.


Table 1. Weed control on June 12 in direct-seeded dry bulb onion treated with various herbicides at the Malheur Experiment Station at Ontario, OR 2012.

Weed control

Treatment Rate Timinga Crop injury Common lambsquarters

Hairy nightshade


oz ai/acre --------------------------------------------- % ------------------------------------------------- Untreated 0 0 0 0 0 Zidua** 1.28 Preemerg 16.3 61 100 95 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Zidua** 1.70 Preemerg 13.8 70 100 95 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Preemerg 6.3 95 100 100 100 Zidua 1.28 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemerg 7.5 94 100 100 100 Zidua 1.70 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant** 8.00 Preemerg 13.8 63 100 95 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant 16.00 Preemerg 10.0 61 100 93 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant** 18.00 Preemerg 2.5 80 100 95 100 GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemerg 3.8 91 100 100 100 Warrant 8.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemerg 8.8 94 100 98 100 Warrant 8.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemerg 6.3 93 100 100 100 Warrant 18.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemerg 5.0 94 100 99 100 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf LSD (P = 0.05) 7.4 14 NS 4 NS

**Visual evaluation on May 12, 2012 (prior to two-leaf treatments) indicate an average of 20 percent injury for these preemergence treatments.


Table 2. Number of onion bulbs in response to various herbicides applied on direct-seeded onion at the Malheur Experiment Station at Ontario, OR, 2012.

Application Number of onion bulbsa Treatment Rate timing Small Medium Jumbo Colossal Supercolossal U.S. No. 1 Total number oz ai/acre ---------------------------------------------------------- no./acre ---------------------------------------------------------- Untreated 35,311 0 0 0 0 0 35,311 Zidua 1.28 Preemergence 1,187 10,979 70,622 24,332 2,967 108,900 110,087 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Zidua 1.70 Preemergence 2,374 10,682 67,654 21,661 3,561 103,559 105,933 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Preemergence 2,374 4,154 76,853 33,827 2,374 117,208 119,582 Zidua 1.28 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 2,374 9,792 77,150 26,706 3,561 117,208 119,582 Zidua 1.70 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant 8.00 Preemergence 1,484 5,341 84,271 24,035 2,374 116,022 117,505 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant 16.00 Preemergence 2,671 11,869 60,830 22,255 2,374 97,328 99,998 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant 18.00 Preemergence 2,374 5,935 74,776 31,750 4,451 116,912 119,286 GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 1,484 5,044 64,094 36,795 3,264 109,197 110,680 Warrant 16.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 2,671 2,967 67,951 33,531 5,638 110,087 112,757 Warrant 8.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 1,780 6,231 78,337 29,376 5,638 119,582 121,363 Warrant 18.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O (Grower std) 15.2 Preemergence 1,484 3,857 52,521 40,355 8,012 104,746 106,229 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf LSD (P = 0.05) 12,836 5,565 19,785 11,252 4,753 17,453 21,484

a Onion were graded to size as follows: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and super colossal (>4¼ inches); and U.S. No. 1 was composed of medium through colossal bulbs.

Table 3. Onion yield in response to various herbicides applied on direct-seeded onion at the Malheur Experiment Station at Ontario, OR, 2012. Application Onion yielda Treatment Rate timing Small Medium Jumbo Colossal Supercolossal U.S. No. 1 Total number oz ai/acre ----------------------------------------------------------------- cwt/acre ----------------------------------------------------------------- Untreated 13.5 0.0 0.0 0.0 0.0 0.0 13.5 Zidua 1.28 Preemergence 2.3 41.9 585.9 299.7 47.5 974.9 977.2 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Zidua 1.70 Preemergence 3.3 38.5 546.5 266.7 57.3 908.9 912.2 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.20 Preemergence 3.7 14.8 666.4 421.0 41.0 1,143.2 1,147.0 Zidua 1.28 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 6.2 34.7 636.5 334.9 60.4 1,066.4 1,072.6 Zidua 1.70 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant 8.00 Preemergence 4.4 20.4 657.2 289.3 40.1 1,007.1 1,011.5 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant 16.00 Preemergence 3.9 44.7 506.6 278.0 38.3 867.6 871.5 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Warrant 18.00 Preemergence 5.5 24.3 623.7 389.3 67.5 1,104.8 1,110.3 GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 4.1 19.6 571.8 467.5 53.0 1,111.9 1,116.0 Warrant 16.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 4.9 11.8 598.7 426.8 94.8 1,132.0 1,137.0 Warrant 8.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O 15.2 Preemergence 2.8 22.3 670.6 355.1 80.6 1,128.6 1,131.4 Warrant 18.00 2-leaf Buctril 2.00 2-leaf GoalTender 2.00 2-leaf Prowl H2O (Grower std) 15.2 Preemergence 3.8 14.9 474.1 525.6 135.0 1,149.5 1,153.2 Buctril 2.00 2-leaf GoalTender 2.00 2-leaf LSD (P = 0.05) 7.9 20.0 162.7 147.1 81.3 178.2 176.1

a Onion were graded to size as follows: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and supercolossal (>4¼ inches); and U.S. No. 1 was composed of medium through colossal bulbs.

2012 POTATO VARIETY TRIALS Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR Introduction New potato varieties were evaluated for their productivity and their suitability for fresh market and processing. Potatoes in Malheur County are grown under contract for processors to make frozen potato products for the food service industry and grocery chain stores. There is very little production for fresh pack or open market, and very few growers store potatoes on their farms. There is also no local production of varieties for making potato chips. The varieties grown for processing in Malheur County, Oregon, are mainly ‘Ranger Russet’, ‘Shepody’, and ‘Russet Burbank’. Harvest begins in July and potatoes arrive at processing plants for storage or processing directly from the field. Prolonged vine growth increases potato yield, but tuber bulking later than mid-August may be limited by the “early die” syndrome, which causes early senescence of the vines of susceptible varieties, especially Shepody and Russet Burbank. Early die in Malheur County is caused by a complex of soil pathogens, including bacteria, nematodes, and fungi, particularly Verticillium wilt. Early die is worse when the crop rotation between potato crops is shorter. Small acreages of new varieties or advanced selections are sometimes grown under contract to study the feasibility of expanding their use. To displace an existing processing variety, a new potato variety must have numerous outstanding characteristics. The yield should be at least as high as the yield of the currently contracted varieties. The tubers need to have low reducing sugars for light fry color, and high specific gravity. A new variety should be resistant to tuber defects or deformities caused by disease, water stress, or heat. It should begin tuber bulking early and grow rapidly for early harvest. Late-harvested varieties should be resistant to early die to continue bulking tubers until harvest. Potato variety development trials at the Malheur Experiment Station in 2012 included the Oregon Statewide Russet Trial with 28 entries, the Preliminary Russet Yield Trial with 50 entries, the Oregon Statewide Specialty Trial of 10 colored skin and/or flesh potato varieties, the Preliminary Yield Specialty Trial of 23 colored skin and/or flesh potato varieties, the Oregon Statewide Chip Trial with 7 entries, and the Preliminary Chip Yield Trial with 13 entries. Through these trials and active cooperation with other scientists in Idaho, Oregon, and Washington, promising new lines are bred and evaluated. Eventually, the best of them may be released as new varieties. Materials and Methods The potato variety trials were grown in 2012 using sprinkler irrigation on Owyhee silt loam, where winter wheat was the previous crop. The soil had a pH of 7 and 1.7 percent organic matter. Based on a soil test, 200 lb phosphate/acre, 80 lb sulfur/acre, 7 lb manganese/acre, and 1 lb boron/acre were broadcast in the fall of 2011. After fertilization the field was fumigated with

2012 Potato Variety Trials 93

Vapam® (metam sodium) at 50 gal/acre and bedded on 36-inch row spacing. On April 12, 2012, 100 lb nitrogen/acre, 1 lb boron/acre, and 20 oz/acre of Admire® (imidacloprid) were shanked in the bed center. Seed of all varieties was cut by hand into 2-oz seed pieces and treated with Topsin® M

(thiophanate-methyl) dust and stored to suberize. Potato seed pieces were planted in single row plots using a 2-row assist-feed planter with 9-inch seed spacing in 36-inch rows. Red potatoes were planted at the end of each plot as markers to separate the potato plots at harvest, except in the specialty trials where russeted potatoes were used as markers. The Oregon Statewide Russet Trial and the Russet Preliminary Yield Trial were planted on April 19. The Oregon Statewide Specialty Trial, the Specialty Preliminary Yield Trial, the Oregon Statewide Chip Trial, and the Chip Preliminary Yield Trial were planted on April 20. All trials, except the preliminary yield trials, had plots that were 30 seed pieces long with 4 replicates. The preliminary yield trials had plots that were 20 seed pieces long and 2 rows wide with 1 replicate. After planting, hills were re-formed over the rows with a Lilliston rolling cultivator. Prowl® H2O at 0.95 lb ai/acre and Dual Magnum® at 1.27 lb ai/acre were applied as a tank mix for weed control on May 2. The herbicides were incorporated with 0.66 inch of precipitation that occurred on May 4 and 5. Matrix® (herbicide) at 0.38 oz ai/acre was applied on May 29 and at 0.25 oz ai/acre on June 25 through the sprinkler system. Emergence started on May 15. Irrigation scheduling was based on a soil water tension criterion of 50-60 cb. Soil water tension was measured at seed piece depth using 6 Watermark soil moisture sensors (Model 200SS, Irrometer Co. Inc., Riverside, CA) connected to dataloggers. Irrigations were managed to maintain soil moisture below 60 cb. Irrigation decisions were based on the average of all 6 sensors. The last irrigation was on September 5. Fertilizer was applied based on petiole tests taken on June 18, July 2, July 18, and August 13. Fertilizer was injected into the sprinkler system during irrigation. During the season, 80 lb nitrogen/acre (as urea-ammonium nitrate solution), 60 lb potassium/acre, 10 lb sulfur/acre, 0.75 lb zinc/acre (Che-Zinc® 9%, Jr. Simplot Co., Boise, ID), and 0.2 lb boron/acre (Concept Boron® 10%, Ag Concepts Corp., Bliss, ID) were applied. The vines were flailed on September 28. The potatoes in each plot were lifted with a two-row digger that laid the tubers back onto the soil in each row from October 8 through October 10. At harvest, visual evaluations were made that included observations of desirable traits (i.e., high yield of large, smooth, uniformly shaped and sized, oblong to long, attractively russeted tubers, with shallow eyes evenly distributed over the tuber length). Observations were also taken of tuber defects such as growth cracks, knobs, thumbnail cracks, curved or irregularly shaped tubers, pointed ends, stem-end decay, attached stolons, heat sprouts, chain tubers, folded bud ends, scab, rough skin due to excessive russeting, pigmented eyes, or any other defect. A note was made for each plot to keep or discard the clone based on the overall appearance of the tubers. Tubers were placed into burlap sacks and placed in a barn where they were kept under tarps until grading. Tubers were graded by market class (U.S. No. 1 and U.S. No. 2) and weight (<4 oz, 4-6 oz, 6-12 oz, and >12 oz). Tubers were graded as U.S. No. 2 if any of the following conditions occurred: growth cracks, bottleneck shape, abnormally curved shape, or two or more knobs. Marketable tubers are U.S. No. 1 and U.S. No. 2 larger than 4 oz. A 20-tuber sample from each


plot was placed into storage. The storage temperature was gradually reduced to 45°F. After 6 weeks, a 10-tuber sample from each plot of the Oregon Statewide Russet Trial, the Russet Preliminary Yield Trial, the State Chip Trial, and the State Chip Preliminary Yield Trial was evaluated for tuber quality traits for processing. Ten tubers per plot of the Oregon Statewide Russet Trial and the Russet Preliminary Yield Trial were cut lengthwise and the 10 center slices were fried for 3.5 min in 375°F soybean oil. For the State Chip Trial and the State Chip Preliminary Yield Trial, 10 tubers per plot were cut into 0.06-inch slices. Percent light reflectance was measured on the stem 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 0 percent light reflectance on the black standard cup and 73.6 percent light reflectance on the white porcelain standard plate. Specific gravity of all varieties was measured from a 10-tuber sample from each plot using the weight-in-air, weight-in-water method. All varieties were evaluated for internal tuber defects from a 10-tuber sample from each plot. Data from all trials were analyzed with the General Linear Models analysis of variance procedure in NCSS (Number Cruncher Statistical Systems, Kaysville, UT) using Fisher's protected LSD (least significant difference) for means separation at the 95 percent confidence level. Results and Discussion Oregon Statewide Trial The lines AO06070-1KF, AO06103-1, CO07240-1KF, AO06929-3KF, AO061003-1KF, and OR008014-4 were among those with the highest total yields (Table 1). AO06070-1KF, CO07240-1KF, and AO06103-1 were among the clones with the highest U.S. No. 1 yields. AO06064-2KF, AO06070-1KF, AO06929-3KF, AO06783-1KF, AO06191-1, OR08014-1, and Ranger Russet were among the clones with the highest specific gravity (measure of tuber solids) in this trial. Numerous clones had percent light reflectance (fry color) higher than 45 percent (Table 1). Tuber internal defects for the clones are listed in Table 2. There were statistically significant differences between clones in all internal defects, except hollow heart (Table 2). Most of the clones and ‘Russet Norkotah’ and Ranger Russet had better visual appearance at harvest than Russet Burbank (Table 3).

Preliminary Russet Yield Trial Of the 50 clones tested, 20 were selected for further testing based on visual observations at harvest (Table 4). Some of the varieties had significantly higher yield and grade and better processing quality than the three commercial varieties in the trial. Some of the clones had better visual appearance at harvest than Russet Norkotah, Ranger Russet or Russet Burbank (Table 5). Tuber internal defects for the clones are listed in Table 6.

Colored Flesh Potato Trials Potato tubers with red to yellow carotinoid or red, blue, and purple anthocyanin pigments are of interest because of the antioxidant properties of these pigments in human nutrition. Two trials tested specialty potato varieties in 2012: Oregon Specialty and Preliminary Yield Specialty.


Oregon Specialty Potato Trial ‘Red La Soda’, OR07309-1, OR08178-1, and PA07NC27-2Y were among the clones with the highest total yield (Table 7). Red La Soda had the highest yield of tubers over 10 oz, an undesirable trait. Red La Soda, ‘Yukon Gold’, and OR08178-1 had average tuber weight greater than 6 oz, an undesirable characteristic for specialty potatoes. Clones PA07NC27-2Y, OR04077-1, POR09NCKL3-1, and OR08178-1 were among those with the highest tuber specific gravity. There were statistically significant differences between clones in vascular discoloration and internal brown spot (Table 8). Exterior appearance observations can be found in Table 9.

Preliminary Specialty Yield Trial Some of the varieties had significantly higher yield and grade and better processing quality than Yukon Gold (Table 10). Tuber internal defects for the clones are listed in Table 11. Exterior appearance observations can be found in Table 12. Oregon Chip Potato Trial ‘Chipeta’ had the highest total yield followed by NDOR071204CB-5 (Table 13). Chipeta had the highest yield of tubers weighing more than 14 oz, an undesirable trait. Of the 7 clones planted, 3 were selected for fry color, specific gravity, and internal defect testing. Tuber internal defects for the clones are listed in Table 14. Clone NDOR071282CB-4 had extremely poor emergence and was not harvested.

Preliminary Chip Yield Trial Clones OR09253-1, AOR00219-3, AOR00199-1a, and Chipeta were among those with the highest total yield (Table 15). Chipeta had the highest yield of tubers weighing more than 14 oz, an undesirable trait. Exterior appearance observations can be found in Table 16.


Table 1. Oregon Statewide Russet Trial potato yield, grade, and processing quality, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

U.S. No. 1 Average fry color,

light reflectance

Variety Total yield

Percent No. 1 Total >12 oz 4-12 oz 6-12 oz 4-6 oz

U.S. No. 2 Marketable <4 oz Cull Rot Length/width

Specific gravity

Sugar ends

cwt/acre % -------------------------------------------- cwt/acre ----------------------------------------------- ratio g cm-3 ------- % --------- Ranger Russet 500.4 81.7 409.4 94.3 315.1 254.1 60.9 39.9 449.3 40.3 10.8 0.0 1.86 1.0980 41.1 0.0 Russet Burbank 481.6 51.5 257.8 41.9 216.0 149.4 66.6 119.5 377.4 47.0 57.2 0.0 1.78 1.0793 34.6 0.0 Russet Norkotah 387.4 79.2 310.6 59.4 251.2 179.2 72.0 17.5 328.1 37.1 22.2 0.0 1.88 1.0727 37.9 0.0 AO05278-1 404.0 79.6 324.8 88.6 236.2 181.9 54.3 2.5 327.3 48.8 28.0 0.0 1.67 1.0924 46.5 0.0 AO05281-1KF 510.9 79.4 407.5 63.1 344.4 258.5 85.9 9.6 417.0 64.8 29.1 0.0 1.74 1.0932 46.0 0.0 AO05286-1KF 484.7 83.0 403.3 29.6 373.6 288.6 85.1 9.7 413.0 46.7 25.1 0.0 1.67 1.0747 36.2 0.0 AO06064-2KF 554.7 89.3 498.9 294.2 204.7 172.5 32.3 13.9 512.8 13.5 27.6 0.8 1.80 1.1159 46.8 0.0 AO06070-1KF 703.4 88.9 625.1 336.1 289.0 234.5 54.5 12.3 637.5 44.4 21.1 0.4 1.74 1.1043 48.1 0.0 POR08NCKP2-1 365.3 57.6 211.9 26.6 185.2 136.6 48.7 41.8 253.6 55.8 44.4 11.5 1.37 1.0625 35.0 0.0 OR08014-1 597.3 79.9 475.0 97.6 377.4 281.8 95.7 31.0 506.0 32.6 58.7 0.0 1.93 1.0982 41.8 0.0 OR08014-4 628.4 78.7 498.9 261.4 237.5 202.4 35.1 32.6 531.6 26.0 70.7 0.1 1.69 1.0954 49.4 0.0 OR08040-1 506.8 75.6 384.9 31.3 353.7 226.2 127.5 11.0 396.0 97.2 13.6 0.0 1.72 1.0876 32.0 0.0 OR08055-1 517.6 83.1 430.9 198.0 232.8 189.0 43.9 18.0 448.8 27.0 41.8 0.0 1.79 1.0944 49.1 0.0 AO06030-5 546.0 69.5 380.3 84.6 295.7 246.6 49.1 46.2 426.5 43.2 76.4 0.0 1.78 1.0963 40.8 0.0 AO06103-1 658.1 85.4 561.7 135.4 426.3 341.0 85.3 3.8 565.5 60.1 32.4 0.0 1.49 1.0885 40.7 0.0 AO06187-1 502.3 67.6 339.5 65.6 273.9 226.6 47.3 40.1 379.6 45.2 77.5 0.0 1.74 1.0762 36.3 0.0 AO06191-1 540.0 89.6 484.5 199.2 285.3 241.2 44.1 14.4 498.9 20.2 20.9 0.0 1.71 1.0989 46.0 0.0 AO07010-1 432.9 87.4 379.6 152.1 227.5 166.4 61.1 18.2 397.8 19.8 14.9 0.3 1.71 1.0828 43.0 0.0 AO07469-2 531.4 82.2 441.1 46.3 394.7 251.0 143.7 4.6 445.6 44.6 41.2 0.0 1.70 1.0727 38.6 0.0 COO07025-1KF 469.1 87.3 410.7 81.3 329.3 274.5 54.8 2.8 413.5 39.8 15.7 0.0 1.86 1.0796 43.2 0.0 COO07092-2KF 355.3 73.4 259.4 102.6 156.8 131.9 24.9 13.5 272.9 19.8 62.5 0.0 1.66 1.0841 48.5 0.0 COO07240-1KF 653.9 86.2 563.6 255.9 307.7 239.1 68.6 27.0 590.7 37.1 26.1 0.0 1.57 1.0872 40.8 0.0 AO06092-1KF 588.0 80.9 478.5 262.1 216.4 171.0 45.4 20.2 498.8 20.8 68.4 0.0 1.79 1.0850 41.0 0.0 AO071020-4KF 473.3 81.4 386.5 98.2 288.2 238.3 49.9 10.7 397.2 21.6 54.6 0.0 1.58 1.0870 40.5 0.0 AO06783-1KF 602.8 82.6 499.2 275.2 224.0 186.6 37.4 21.7 520.9 16.8 65.1 0.0 1.90 1.1023 41.5 0.0 AO06732-1KF 506.2 86.0 436.5 134.5 302.0 249.7 52.4 9.5 446.0 32.9 27.3 0.0 1.57 1.0902 38.7 0.0 AO06929-3KF 651.7 76.4 500.4 61.2 439.2 321.6 117.6 20.7 521.1 78.4 52.2 0.0 1.80 1.1025 46.4 0.0 AO061003-1KF 630.0 81.7 513.3 70.9 442.5 318.6 123.8 9.6 522.9 83.6 23.5 0.0 1.67 1.0935 41.6 0.0 Mean 528.0 79.5 424.1 130.3 293.8 227.1 66.7 22.2 446.3 41.6 39.6 0.5 1.72 1.0891 41.9 0.0 LSD (0.05) 86.8 11.3 103.2 59.2 85.6 72.2 33.7 23.5 101.1 17.1 44.1 3.2 0.22 0.0192 3.5 NS

Table 2. Oregon Statewide Russet Trial tuber internal defects, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety Vascular

discoloration Hollow heart

Internal brown spot

Stem end browning

-------------------------- % ---------------------------- Ranger Russet 2.5 0 7.5 12.5 Russet Burbank 0.0 0 10.0 10.0 Russet Norkotah 0.0 0 5.0 7.5 AO05278-1 5.0 0 2.5 10.0 AO05281-1KF 0.0 0 7.5 27.5 AO05286-1KF 0.0 0 2.5 10.0 AO06064-2KF 2.5 0 7.5 17.5 AO06070-1KF 0.0 0 5.0 2.5 POR08NCKP2-1 0.0 0 15.0 50.0 OR08014-1 0.0 0 12.5 25.0 OR08014-4 0.0 2.5 7.5 20.0 OR08040-1 0.0 0 5.0 2.5 OR08055-1 7.5 2.5 5.0 15.0 AO06030-5 2.5 0 12.5 15.0 AO06103-1 10.0 0 2.5 2.5 AO06187-1 15.0 0 15.0 27.5 AO06191-1 0.0 0 7.5 20.0 AO07010-1 0.0 0 10.0 15.0 AO07469-2 2.5 0 2.5 7.5 COO07025-1KF 0.0 0 5.0 20.0 COO07092-2KF 0.0 0 12.5 22.5 COO07240-1KF 2.5 0 5.0 25.0 AO06092-1KF 0.0 0 2.5 2.5 AO071020-4KF 2.5 0 7.5 7.5 AO06783-1KF 2.5 0 40.0 30.0 AO06732-1KF 0.0 0 5.0 7.5 AO06929-3KF 0.0 0 7.5 5.0 AO061003-1KF 0.0 0 5.0 5.0 Mean 2.0 0.2 8.3 15.1 LSD (0.05) 7.8 NS 11.6 21.1


Table 3. Oregon Statewide Russet Trial tuber visual observations at harvest. Tuber defect observations are from a total of four plots for each clone. K = clone should be kept, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters. Since there were four replicates, a clone could be scored for the same attribute up to four times. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety K or D Description Ranger Russet 3d, 1k 2 dumbbell, 2 curves, 3 hearts, 1 bottleneck, 2 Growth Cracks, 3 pointed, 2 knobs, 1 growth crack Russet Burbank 4D 2 bottleneck, 3 dumbbell, 3 Growth Crack,1 growth crack, 2 irregular shape, 1 knob, 4 pointed, 3 curved Russet Norkotah 3k, 1d 1 alligator hide, 2 heart, 2 irregular shape, 3 pointed AO05278-1 2k, 2K 3 irregular color, 1 knob, 1 swollen lenticels, 1 curved AO05281-1KF 1K, 1k, 2d 2 irregular shape, 1 pointed, 1 curved, 2 scab AO05286-1KF 2k, 2K 3 heart, 3 irregular shape, 2 pointed, 1 flaky skin AO06064-2KF 3K, 1k 1 dumbbell, 3 irregular shape, 2 pointed, 1 swollen lenticels, 3 curved AO06070-1KF 4K 1 alligator hide, 3 irregular shape, 3 pointed POR08NCKP2-1 2D, 1k, 1d 1 Alligator Hide, 1 bottle neck, 2 irregular shape, 1 Irregular Shape, 3 knob, 3 pointed, 1 small OR08014-1 2k, 2d 1 bottle neck, 2 dumbbell, 3 growth crack, 1 knob, 1 pointed, 2 curved, 2 Curved OR08014-4 4K 1 alligator hide, 1 growth crack, 2 heart, 3 irregular shape, 1 knob, 1 pointed, 2 swollen lenticels OR08040-1 3K, 1d 1 growth crack, 1 heart, 2 pointed, 1 small OR08055-1 2k, 2K 3 heart, 2 irregular shape, 1 knob, 2 pointed, 3 swollen lenticels AO06030-5 2k, 1D, 1d 1 bottle neck, 1 dumbbell, 1 Dumbbell, 2 growth crack, 1 Growth Crack, 1 heart, 2 irregular shape, 1 Irregular Shape AO06103-1 2k, 1K, 1d 1 growth crack, 4 irregular shape, 4 pointed, 1 small, AO06187-1 1k, 1d, 2D 3 alligator hide, 1 dumbbell, 2 growth crack, 1 heart, 2 irregular shape, 1 Irregular Shape, 2 knob, 3 pointed,

1 curved, 1 Curved AO06191-1 3K 1 dumbbell, 1 growth crack, 2 heart, 1 irregular shape, 1 folded bud end AO07010-1 1d, 2K, 1k 2 growth crack, 3 heart, 4 irregular shape, 1 curved AO07469-2 1k, 3K 1 alligator hide, 1 growth crack, 1 irregular shape, 2 swollen lenticels, 1 curved COO07025-1KF 4K 2 irregular shape COO07092-2KF 2k, 2K 1 heart, 1 Heart, 1 irregular shape COO07240-1KF 2K, 2k 1 alligator hide, 1 bottle neck, 3 growth crack, 2 heart, 4 irregular shape, 1 knob, 1 pointed AO06092-1KF 1K, 2k,1D 1 dumbbell, 4 heart, 2 irregular shape, 2 pointed, 1 Pointed, 2 swollen lenticels, 1 curved, 1 Curved AO071020-4KF 1d, 3K 1 alligator hide, 2 growth crack, 1 irregular shape, 1 knob, 1 swollen lenticels, 4 folded bud end AO06783-1KF 3D, 1d 3 Alligator Hide, 1 Growth Crack, 1 heart, 1 irregular shape, 1 Pointed, 1 pointed, 2 Curved AO06732-1KF 2k, 2K 1 growth crack, 1 heart, 4 irregular shape, 1 knob, 1 pointed, 2 swollen lenticels AO06929-3KF 1d, 1k, 2K 1 dumbbell, 3 irregular shape, 3 pointed, 2 swollen lenticels, 1 small, 2 curved AO061003-1KF 2K, 2k 1 heart, 4 irregular shape,1 pointed, 1 small

Table 4. Preliminary Russet Yield Trial yield, grade, and processing quality for selected varieties. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

U.S. No. 1 Average fry color, light reflectance

Variety Total yield

Percent No. 1 Total

>12 oz

4-12 oz

6-12 oz

4-6 oz

U.S. No. 2 Marketable <4 oz Cull Rot Length/width

Specific gravity

Sugar ends

cwt/acre % ----------------------------------- cwt/acre ------------------------------------ ratio g cm-3 ------- % -------

Ranger Russet 529.1 63.5 336.0 77.9 258.1 175.8 82.3 55.1 391.1 82.3 55.8 0.0 1.87 1.0976 43.1 0.0 Russet Burbank 522.5 51.3 268.1 42.7 225.4 156.8 68.6 153.7 421.9 74.7 25.9 0.0 2.05 1.0741 33.9 0.0 Russet Norkotah 243.2 69.3 168.5 19.1 149.4 85.9 63.5 7.2 175.6 54.8 12.8 0.0 1.81 1.0781 38.5 0.0 AOR06550-2 547.4 67.3 368.4 38.0 330.4 229.6 100.8 43.9 412.3 66.6 68.5 0.0 1.52 1.0970 46.7 0.0 AOR06565-1 593.6 77.6 460.5 111.1 349.4 265.8 83.5 48.8 509.3 49.0 35.3 0.0 1.73 1.1012 50.9 0.0 AOR06987-6 389.1 88.2 343.2 40.8 302.3 198.4 103.9 1.5 344.7 40.7 3.8 0.0 1.79 1.0923 50.1 0.0 AOR061075-1 513.2 80.1 411.1 58.0 353.1 235.8 117.3 17.0 428.1 78.3 6.8 0.0 1.83 1.0966 49.5 0.0 AOR061076-2 571.6 78.4 448.3 115.2 333.1 230.1 103.0 9.3 457.6 92.2 21.9 0.0 1.57 1.0960 41.3 0.0 AOR07888-3 854.6 77.6 663.2 141.3 521.8 399.5 122.4 50.8 714.0 80.6 60.0 0.0 1.64 1.1029 50.0 0.0 AOR07919-4 630.9 80.7 509.5 121.5 388.0 312.4 75.6 20.5 530.0 53.9 47.0 0.0 1.80 1.0850 40.3 0.0 AOR08056-1 481.7 69.3 333.6 0.0 333.6 180.2 153.3 10.5 344.0 112.0 25.7 0.0 1.58 1.0874 52.0 0.0 AOR08662-5 512.2 80.7 413.5 17.2 396.3 247.7 148.6 28.1 441.6 69.7 0.9 0.0 1.52 1.0985 48.8 0.0 OR09124-1 379.9 81.4 309.1 29.6 279.5 193.1 86.4 19.0 328.1 47.5 1.6 2.6 1.69 1.0933 53.0 0.0 OR09126-1 544.9 88.6 482.8 177.7 305.1 237.3 67.9 16.5 499.3 36.2 9.4 0.0 1.83 1.0914 46.0 0.0 OR09156-1 568.2 78.3 444.8 161.7 283.1 239.3 43.9 20.4 465.2 38.1 64.9 0.0 1.75 1.0932 42.7 0.0 OR09415-2 740.9 77.4 573.4 44.5 528.9 335.3 193.6 25.6 599.0 121.3 20.6 0.0 1.52 1.0811 35.0 0.0 OR08OP289-2 569.1 67.1 381.8 127.4 254.4 186.2 68.1 105.8 487.6 52.1 29.4 0.0 2.00 1.0816 44.7 0.0 COOR07208-1KF 763.5 71.2 543.6 263.5 280.1 230.1 50.0 29.6 573.2 53.7 134.1 2.4 1.73 1.0811 45.2 0.0 COOR08294-2KF 529.5 71.4 378.3 39.4 338.9 224.8 114.1 2.9 381.2 111.0 37.3 0.0 1.86 1.0940 50.9 0.0 COOR08181-1KF 832.7 79.2 659.8 197.4 462.4 343.3 119.2 24.7 684.5 83.5 64.7 0.0 1.88 1.0779 44.1 0.0 Average 565.9 74.9 424.9 91.2 333.7 235.4 98.3 34.5 459.4 69.9 36.3 0.3 1.7 1.1 45.3 0.0

Table 5. Preliminary Russet Yield Trial tuber visual observations at harvest for selected varieties. K = clone should be kept, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety K or D Description Ranger Russet D Curved, Pointed, Irregular Shape, heart, Knob Russet Burbank D Irregular Shape, Pointed, Bottle Neck, Knob Russet Norkotah K irregular shape, pointed, heart AOR06550-2 d/k pointed, irregular shape, curved AOR06565-1 d pointed, irregular shape, curved AOR06987-6 D Pointed, small AOR061075-1 D Irregular Shape, Pointed, small, jelly end rot AOR061076-2 k or d pointed, irregular shape AOR07888-3 D Pointed or Small AOR07919-4 k irregular shape, pointed AOR08056-1 K irregular shape, small AOR08662-5 K irregular shape OR09124-1 K pointed OR09126-1 K pointed OR09156-1 D Pointed, irregular shape, heart OR09415-2 k irregular shape, pointed OR08OP289-2 D Pointed, Curved, Irregular Shape, heart COOR07208-1KF K irregular shape, pointed, growth crack, dumbbell COOR08294-2KF k nice appearance COOR08181-1KF k Curved, pointed


Table 6. Preliminary Russet Yield Trial tuber internal defects, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety Vascular discoloration Hollow heart Internal brown spot Stem end browning

-------- % -----------

Ranger Russet 0.0 0.0 0.0 10.0 Russet Burbank 20.0 0.0 10.0 10.0 Russet Norkotah 0.0 0.0 0.0 10.0 AOR06550-2 0.0 0.0 0.0 10.0 AOR06565-1 0.0 0.0 0.0 0.0 AOR06987-6 0.0 0.0 0.0 10.0 AOR061075-1 0.0 0.0 0.0 20.0 AOR061076-2 10.0 0.0 10.0 10.0 AOR07888-3 0.0 0.0 0.0 10.0 AOR07919-4 0.0 10.0 10.0 0.0 AOR08056-1 0.0 0.0 0.0 0.0 AOR08662-5 60.0 0.0 0.0 0.0 OR09124-1 0.0 0.0 20.0 10.0 OR09126-1 0.0 0.0 0.0 10.0 OR09156-1 0.0 0.0 20.0 0.0 OR09415-2 10.0 0.0 0.0 10.0 OR08OP289-2 60.0 0.0 0.0 10.0 COOR07208-1KF 10.0 0.0 10.0 10.0 COOR08294-2KF 0.0 0.0 10.0 10.0 COOR08181-1KF 10.0 0.0 10.0 0.0 Average 9.0 0.5 5.0 7.5


Table 7. Oregon Statewide Specialty Potato Trial yield and grade of colored flesh clones, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. U.S. No. 1 Average

tuber weight

No. of tubers /plant

Clone/Variety Total yield

< 4 oz

4-6 oz

6-10 oz

4-10 oz

<10 oz

>10 oz

U.S. No. 2 Cull

Twos + culls

Rotten tubers

Specific gravity

--------------------------------------------------- cwt/acre ---------------------------------------------------- oz

g cm-3 Yukon Gold 399.3 45.6 61.5 145.2 206.7 252.3 127.5 7.3 12.2 19.5 0.0 6.8 4.8 1.0800 All Blue 426.4 200.2 104.4 78.0 182.4 382.6 12.9 13.0 17.9 30.9 0.0 3.5 10.1 1.0763 Purple Majesty 565.3 246.0 177.6 93.1 270.7 516.7 4.0 20.4 24.2 44.6 0.0 3.8 12.5 1.0778 Red La Soda 675.5 72.6 91.5 235.6 327.1 399.7 230.6 11.1 34.1 45.2 0.0 7.3 7.7 1.0747 OR04077-1 506.6 171.7 127.7 130.1 257.8 429.4 45.8 8.0 23.4 31.4 0.0 5.0 8.8 1.0919 OR07309-1 614.9 313.0 163.6 75.7 239.3 552.2 18.4 21.8 22.5 44.3 0.0 3.5 14.7 1.0752 OR08178-1 597.5 82.7 95.3 146.5 241.8 324.5 183.8 48.5 40.2 88.7 0.5 6.7 7.4 1.0872 POR09PG57-1 453.4 176.4 36.4 10.9 47.3 223.7 0.0 176.5 44.6 221.1 8.7 2.4 16.2 1.0575 POR09NCKL3-1 377.2 283.3 31.4 15.3 46.7 330.0 17.0 10.3 16.7 26.9 3.2 2.4 12.9 1.0885 PA07NC27-2Y 584.3 210.8 152.7 140.6 293.3 504.1 32.3 21.3 26.6 47.9 0.0 4.9 10.0 1.0965 Mean 520.0 180.2 104.2 107.1 211.3 391.5 67.3 33.8 26.2 60.0 1.2 4.6 10.5 1.0806 LSD (0.05) 101.8 41.7 27.7 39.1 48.7 66.2 43.0 24.6 NS 38.0 5.0 1.0 2.1 0.0101

Table 8. Oregon Statewide Specialty Potato Trial tuber internal defects of colored flesh clones, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Clone/Variety Vascular

discoloration Hollow heart

Internal brown spot

Stem end browning Zebra chip

-------- % ----------- Yukon Gold 30.0 0.0 37.5 10.0 7.5

All Blue 35.0 0.0 0.0 7.5 0.0 Purple Majesty 7.5 0.0 0.0 0.0 0.0 Red La Soda 40.0 0.0 27.5 10.0 15.0 OR04077-1 47.5 2.5 7.5 5.0 5.0 OR07309-1 25.0 7.5 67.5 15.0 7.5 OR08178-1 30.0 0.0 27.5 10.0 10.0 POR09PG57-1 55.0 2.5 15.0 5.0 0.0 POR09NCKL3-1 5.0 0.0 10.0 0.0 10.0 PA07NC27-2Y 35.0 5.0 22.5 15.0 12.5 Mean 31.0 1.8 21.5 7.8 6.8 LSD (0.05) 24.4 NS 19.0 NS NS

Table 9. Oregon Specialty Trial tuber visual observations at harvest. Tuber defect observations are from a total of four plots for each clone. K = clone should be kept, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters. Since there were four replicates, a clone could be scored for the same attribute up to four times. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Clone/Variety K or D Description Yukon Gold 2k, 1D, 1d 1 alligator hide, 1 Scab, 1 scab All Blue 1d, 3D 1 dumbbell, 3 irregular shape, 1 Irregular Shape, 1 knob, 1 Knob, 1 pointed, 2 curved Purple Majesty 3d 1 pointed Red La Soda 4D 3 Irregular Shape, 1 water rot, 3 deep eyes, 4 folded bud end OR04077-1 3k, 1K OR07309-1 2d, 1K, 1D 1 deep eyes OR08178-1 2k, 1d,1D 1 growth crack, 3 heart, 2 irregular shape, 2 Irregular Shape, 2 pointed, 1 Pointed, 1swollen lenticels, 2 scab POR09PG57-1 4D 1 bottle neck, 2 dumbbell, 1 Dumbbell, 1 irregular shape, 3 knob, 3 pointed, 1Jelly End Rot POR09NCKL3-1 4K

PA07NC27-2Y 2k, 2K

Table 10. Preliminary Specialty Potato Yield Trial yield, grade, and processing quality for selected varieties, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. U.S. No. 1 Average

tuber weight


Variety Total yield <4 oz

4-6 oz

6-10 oz

4-10 oz

<10 oz

>10 oz

U.S. No. 2 Cull

Twos + culls

Rotten tubers

Specific gravity

-------------------------------------------------- cwt/acre --------------------------------------------------- oz

g cm-3 Yukon Gold 337.3 58.3 71.9 129.5 201.4 259.7 43.4 2.2 31.9 34.1 0.0 5.7 6.5 1.0900 All Blue 357.8 191.0 67.7 40.5 108.2 299.3 10.0 42.2 6.3 48.5 0.0 2.8 14.2 1.0754 POR10PG3-1 259.2 207.4 32.9 9.2 42.1 249.6 0.0 4.0 2.3 6.2 3.4 2.3 12.6 1.0884 POR10PG3-3 143.1 138.9 0.0 0.0 0.0 138.9 0.0 1.9 2.3 4.2 0.0 1.3 12.0 1.0971 POR10PG3-5 289.6 247.7 14.3 0.0 14.3 262.0 0.0 27.4 0.0 27.4 0.2 2.0 15.9 1.0804 POR10PG3-6 223.2 143.7 0.0 0.0 0.0 143.7 0.0 75.2 4.3 79.4 0.0 1.1 22.4 1.0917 POR10PG3-9 200.7 134.5 0.0 0.0 0.0 134.5 0.0 64.8 1.5 66.3 0.0 0.4 58.3 1.0746 POR10PG10-1 342.3 279.4 29.1 2.4 31.5 310.9 0.0 23.8 7.6 31.5 0.0 2.1 18.2 1.0854 POR10PG13-1 122.8 121.6 0.0 0.0 0.0 121.6 0.0 1.0 0.2 1.2 0.0 1.4 9.3 1.0738 POR10PG53-1 270.2 217.8 30.1 11.7 41.8 259.6 0.0 6.1 4.5 10.6 0.0 2.1 14.5 1.0753 POR10PG53-3 309.2 261.7 26.4 1.8 28.2 289.9 0.0 7.6 11.7 19.3 0.0 1.8 19.4 1.0651 POR10PG53-5 224.7 198.5 1.4 0.0 1.4 199.8 0.0 11.2 13.6 24.9 0.0 1.3 18.7 1.0651 POR10PG53-6 399.2 264.2 63.8 26.2 90.0 354.2 3.0 22.9 19.0 41.9 0.0 1.9 22.6 1.0587 POR10PG53-7 202.5 202.4 0.0 0.0 0.0 202.4 0.0 0.0 0.1 0.1 0.0 1.4 16.4 1.0747 AOR08695-11 454.6 319.4 112.2 18.6 130.9 450.3 0.0 3.9 0.3 4.3 0.0 2.8 18.2 1.0854 AOR06262-1 636.8 104.0 172.5 242.2 414.8 518.8 114.5 0.7 2.9 3.5 0.0 5.4 13.1 1.0830 AOR06262-2 818.9 263.8 174.6 276.5 451.0 714.9 55.4 13.8 34.8 48.7 0.0 4.1 22.2 1.0738 AOR06262-7 845.5 220.1 145.6 94.7 240.3 460.4 15.4 35.6 334.1 369.7 0.0 5.5 16.8 1.0825 AOR06267-3 446.9 218.2 102.1 42.4 144.4 362.7 0.0 61.7 22.6 84.3 0.0 2.6 18.9 1.0718 AOR07230-1 462.8 130.8 131.6 124.3 255.9 386.7 17.6 22.2 36.3 58.5 0.0 4.7 10.9 1.0700 AOR07364-1 399.1 279.5 80.6 32.7 113.4 392.9 0.0 4.1 2.2 6.2 0.0 2.7 16.4 1.0957 COOR08040-2 415.0 240.1 111.1 44.4 155.6 395.7 0.0 19.3 0.0 19.3 0.0 3.2 14.4 1.0754 OR09387-1 542.0 272.3 171.6 76.2 247.8 520.1 0.0 15.6 6.3 21.9 0.0 4.9 12.3 1.0822 Average 378.4 205.0 66.9 51.0 118.0 323.0 11.3 20.3 23.7 44.0 0.2 2.7 17.6 1.1

Table 11. Preliminary Specialty Potato Yield Trial tuber internal defects, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety Vascular

discoloration Hollow heart Internal brown

spot Stem end browning

-------- % ----------- Yukon Gold 10.0 0.0 40.0 0.0 All Blue 20.0 0.0 0.0 0.0 POR10PG3-1 30.0 0.0 0.0 0.0 POR10PG3-3 70.0 0.0 30.0 0.0 POR10PG3-5 90.0 0.0 0.0 0.0 POR10PG3-6 90.0 0.0 70.0 0.0 POR10PG3-9 90.0 0.0 0.0 0.0 POR10PG10-1 0.0 0.0 0.0 10.0 POR10PG13-1 0.0 0.0 20.0 0.0 POR10PG53-1 50.0 0.0 20.0 0.0 POR10PG53-3 30.0 10.0 40.0 40.0 POR10PG53-5 40.0 0.0 10.0 0.0 POR10PG53-6 30.0 30.0 80.0 20.0 POR10PG53-7 60.0 0.0 20.0 0.0 AOR08695-11 50.0 0.0 30.0 10.0 AOR06262-1 10.0 0.0 10.0 0.0 AOR06262-2 40.0 0.0 10.0 0.0 AOR06262-7 10.0 0.0 20.0 0.0 AOR06267-3 40.0 0.0 0.0 10.0 AOR07230-1 60.0 0.0 40.0 20.0 AOR07364-1 40.0 0.0 20.0 0.0 COOR08040-2 0.0 0.0 0.0 0.0 OR09387-1 40.0 0.0 10.0 10.0 Average 39.1 1.7 20.4 5.2

Table 12. Preliminary Specialty Potato Yield Trial tuber visual observations at harvest. K = clone should be kept, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety K or D Description Yukon Gold d Scab All Blue D Pointed, Small, Irregular, swollen lenticels, knob POR10PG3-1 D Deep Eyes, sprouts, lumpy, nice internal color POR10PG3-3 d sprouts, Irregular Shape POR10PG3-5 d sprouts POR10PG3-6 D Pointed, sprouts POR10PG3-9 d sprout, knob, would require sandy soil to produce POR10PG10-1 D unattractive skin, Pointed, Dumbbell POR10PG13-1 k skin not attractive, Irregular Shape, very low yield POR10PG53-1 D sprouts, flaky skin POR10PG53-3 D sprout s POR10PG53-5 D sprouts POR10PG53-6 D sprouts POR10PG53-7 D sprouts AOR08695-11 ? nice small yellow, pointed, irregular shape AOR06262-1 k lumpy AOR06262-2 k

AOR06262-7 D AOR06267-3 D Jelly End Rot, Bottle Neck, Pointed, Heart

AOR07230-1 K nice AOR07364-1 K nice COOR08040-2 k nice, some unattached skin OR09387-1 k pointed, some loose skin

Table 13. Oregon Statewide Chip Potato Trial yield and grade. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety Total yield

>14 oz

10-14 oz

6-10 oz

4-6 oz <4 oz

<1¾ inch Cull Rot

Average tuber

weight

No. of tubers /plant Length/width

Specific gravity

Average fry color, light reflectance

--------------------------------- cwt/acre ---------------------------------- oz

ratio g cm-3 ----- % ----- Chipeta 777.0 335.8 163.6 166.0 44.1 39.8 9.4 17.5 0.8 9.4 6.8 1.24 1.0840 46.2 NDOR071109C-1 422.6 7.0 36.1 151.5 124.4 83.3 11.4 8.9 0.0 4.7 7.3

NDOR071109C-2 371.2 34.5 56.3 165.3 66.6 33.2 7.4 7.9 0.0 6.1 4.9

NDOR071204CB-5 581.4 110.0 91.9 181.3 82.9 62.7 7.9 43.6 1.2 6.9 6.9 1.26 1.0895 47.3 NDOR071227CB-1 406.6 0.0 1.1 50.8 120.5 177.7 21.3 35.2 0.0 3.5 9.1 1.14 1.0871 44.5 NDOR071282CB-2 392.6 19.6 31.1 136.9 92.9 60.6 8.1 43.4 0.0 5.2 6.1

Mean 491.9 84.5 63.3 142.0 88.6 76.2 10.9 26.1 0.3 6.0 6.9 1.2 1.0869 46.0 LSD (0.05) 112.7 48.1 17.6 60.9 30.2 31.8 6.3 25.3 NS 0.8 2.0 NS NS NS

Table 14. Oregon Statewide Chip Potato Trial tuber internal defects for selected clones, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety Vascular discoloration Hollow heart Internal brown spot Stem end browning -------- % ----------- Chipeta 5.0 2.5 22.5 0.0 NDOR071204CB-5 3.3 10.0 13.3 0.0 NDOR071227CB-1 5.0 2.5 12.5 0.0 Mean 4.4 5.0 16.1 0.0 LSD (0.05) NS NS NS NS

Table 15. Preliminary Chip Yield Trial yield, grade, and processing quality for selected varieties. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Variety Total yield

>14 oz

10-14 oz

6-10 oz

4-6 oz <4 oz

<1¾ inch Cull Rot

Average tuber weight


---------------------------------- cwt/acre --------------------------------- oz Chipeta 697.5 345.0 119.6 103.9 47.5 24.1 2.565 43.0 0.0 9.86 7.6

AOR00199-1a 764.0 23.1 82.3 335.5 194.1 76.0 12.83 39.8 0.0 5.45 15.2 AOR00218-1 655.7 107.4 145.7 227.6 62.5 32.0 8.809 58.2 2.9 7.08 9.9 AOR00219-3 765.5 57.9 123.3 284.5 110.6 68.2 14.18 90.7 0.0 6.15 13.2 AOR01144-1 524.8 45.1 103.6 200.0 83.4 48.1 12.78 33.4 0.0 5.96 9.5 AOR01144-3 268.9 0.0 0.0 20.3 112.2 127.1 24.59 5.6 1.8 3.27 9.0 AOR01144-5 447.7 51.0 86.7 197.6 72.9 32.4 5.421 5.4 0.0 6.83 7.2 AOR08087-4 514.8 9.8 71.8 225.9 103.0 93.9 17.28 7.8 0.0 5.12 11.0 AOR08090-2 447.0 0.0 3.0 188.6 174.8 67.3 11.71 10.0 0.0 4.97 9.8 AOR08094-2 416.4 0.0 22.7 111.4 127.3 133.0 25.51 16.6 0.0 3.86 11.7 OR09253-1 830.6 18.5 109.0 347.4 165.5 143.7 24.3 34.8 0.0 5.08 17.8 OR09256-2 338.7 0.0 12.7 168.3 104.3 40.2 13.36 9.9 0.0 4.76 7.8 OR09260-1 421.5 0.0 3.8 158.3 142.5 113.8 27.93 2.3 0.0 3.87 12.0 Mean 545.6 50.6 68.0 197.6 115.4 76.9 15.5 27.5 0.4 5.6 10.9

Table 16. Preliminary Chip Yield Trial tuber visual observations at harvest. K = clone should be kept, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters. Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Clone K or D Description Chipeta d irregular, somewhat russetted, deep eyes, Folded bud end AOR00199-1a d irregular, pear shaped, growth cracks AOR00218-1 d folded bud end, Irregular, deep eyes AOR00219-3 K pointed, knobs AOR01144-1 K irregular AOR01144-3 d small AOR01144-5 K folded bud end, deep eyes, round AOR08087-4 d a few sprouts AOR08090-2 k irregular AOR08094-2 k small OR09253-1 k

OR09256-2 k OR09260-1 k

RESPONSE OF SEVERAL ROTATIONAL CROPS TO FOMESAFEN (REFLEX®) HERBICIDE SOIL RESIDUES Joel Felix and Joey Ishida, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Introduction Fomesafen (Reflex®) is currently registered in specific counties in Idaho for weed control in potato, but not in Oregon and Washington. Registration in Oregon will depend on the response of rotational crops grown subsequent to potato treated with fomesafen. Fomesafen has a potential to improve yellow nutsedge control in potato, especially when used as a tank-mix partner with other products including S-metolachlor (Dual Magnum®) and dimethenamid-p (Outlook®). Studies conducted at the Malheur Experiment Station in 2010 indicated that fomesafen controls most annual broadleaf weeds and provides partial control of yellow nutsedge. The objective of this study was to evaluate the response of crops grown following potato (rotational crops) to fomesafen (Reflex) herbicide soil residues. No injury was observed on winter wheat var. ‘Stephens’ and spring wheat var. ‘Alturas’ planted 179 and 293 days after herbicide application, respectively. Similarly, pinto bean var. ‘Windbreaker’ was not injured by fomesafen soil residues when planted 360 days after herbicide application. However, spring barley var. ‘Millennium’ planted 293 days after herbicide application was injured 48 to 72 percent and grain yield reduced 19 percent compared to the grower standard. Also, sugar beet hybrid 27RR20 planted 324 days after herbicide application was injured 13 to 95 percent across treatments. Residues from fomesafen applied at 0.5 lb ai/acre were more injurious and reduced sugar beet root yield and estimated recoverable sugar by 35 percent and 41 percent, respectively. Dry bulb onion var. ‘Vaquero’ planted 296 days after herbicide application were injured 92 percent and the U.S. No. 1 bulb yield reduced 60 percent compared to the grower standard. Onion injury was in plots that were treated with fomesafen at 0.5 lb ai/acre, but not at 0.25 lb ai/acre, which is the targeted use rate. The results suggested that winter and spring wheat, onion, and pinto bean could be planted safely following application of fomesafen at 0.25 lb ai/acre to control weeds in potato.

Materials and Methods A study was established in 2011 at the Malheur Experiment Station in a field previously planted to wheat to evaluate 1) fomesafen herbicide for weed control when applied alone or as a tank-mix partner with standard potato herbicides, and 2) the response of subsequent crops to soil residues when grown following potato (rotational crops). No injury to potato was observed and the data are not included in this report. Tillage operations during the preceding fall followed standard practices for potato production. The soil was an Owyhee silt loam with a pH of 7.7 and 1.89 percent organic matter. Seven rotational crops (winter and spring wheat, dry bulb onion, sugar beet, sweet corn, pinto bean, and barley) were planted in 2012 to assess the response to fomesafen soil residues (Table 1).

Response of Several Rotational Crops to Fomesafen (Reflex®) Herbicide Soil Residues 112

The study design was a split-plot, with four herbicide treatments forming the main plots onto which seven rotational crops were randomly assigned as subplots in 2012. Each main plot was 63 ft wide (21 rows) by 30 ft long with 3 replications. Herbicide treatments are contained in Tables 2-7. In order to minimize weed competition in crops grown in 2012, plots were kept weed free with periodic hand weeding. Herbicide treatments were applied on May 21, 2011 before potato and weed emergence using a pressurized CO2 backpack sprayer fitted with a boom equipped with 6 EVS8002 flat-fan nozzles at a spray volume of 20 gal/acre. Plots were sprinkler irrigated immediately after herbicide application to incorporate herbicides in the soil. Subsequent irrigations were scheduled based on six Watermark soil moisture sensors (Irrometer Co., Riverside, CA) connected to an AM400 data logger (M.K. Hansen Co., Wenatchee, WA) to prevent the soil at the seed-piece depth from drying beyond 60 kPa soil water tension. Table 1. Rotational crops with planting dates and the number of days after herbicide application. Crop variety Planting date Number of days after herbicide application Winter wheat (var. Stephens) 11/16/2011 179 Spring wheat (var. Alturas) 03/09/2012 293 Spring barley (var. Millennium) 03/09/2012 293 Pinto bean (var. Windbreaker) 05/15/2012 360 Sugar beet (hybrid 27RR20) 04/09/2012 324 Dry bulb onion (var. Vaquero) 03/12/2012 296 Sweet corn (var. Golden Bantum) 05/09/2012 354

Crops were grown following local procedures and harvested at maturity to determine yield. All rotational crops were furrow irrigated. Plants were evaluated for injury based on a 0 percent (no apparent injury) to 100 percent (complete crop damage). Data were subjected to analysis of variance using PROCGLM in SAS and means were compared using Fisher’s protected least significant difference procedure at P ≤ 0.05.

Results and Discussion Evaluations conducted April 17 and May 21, 2012 indicated no apparent injury to winter wheat and spring wheat planted 179 and 293 days after herbicide application (Tables 2 and 3). The grain yield was similar across treatments and ranged from 83 to 97 cwt/acre for winter wheat and 65 to 78 cwt/acre for spring wheat. These results suggested that winter wheat var. Stephens and spring wheat var. Alturas could be safely planted in the Treasure Valley the fall and spring following fomesafen application, respectively. Similarly, there was no injury observed on pinto bean (var. Windbreaker) planted 360 days after fomesafen application (Table 4). The bean yield ranged from 4,178 to 4,447 lb/acre for treatments that included formasafen compared to 3,545 lb/acre for the grower standard. Fomesafen soil residues injured spring barley (var. Millennium) planted 293 days after herbicide application (Table 5). Visible injury was characterized by chlorosis followed by wilting of the


first and third leaf about 10 days after emergence. The leaf sheath and plant stems developed brown/purple specks that persisted throughout the growing season. The injury ranged from 48 to 72 percent on April 17 and 10 to 37 percent on May 21, 2012. The average grain yield reduction for spring barley was 19 percent compared to the grower standard. Sugar beet hybrid 27RR20 planted 324 days after fomesafen application was injured 13 to 95 percent on April 17 and 8 to 93 percent on May 21, 2012 (Table 6). The injury was characterized by wilting and dying of seedlings in the plots previously treated with fomesafen at 0.5 lb ai/acre. The injury reduced root and estimated recoverable sugar by 35 percent and 40 percent, respectively, compared to the grower standard treatment. Onion variety Vaquero planted 296 days after herbicide application was tolerant of fomesafen residues when applied at 0.25 lb ai/acre (which is the targeted use rate) (Table 7). Soil residues from fomesafen at 0.5 lb ai/acre were injurious to dry bulb onion. The injury for plants growing in plots previously treated with fomesafen at 0.5 lb ai/acre was 92 percent compared to the grower standard. The injury resulted in 60 percent reduction for U.S. No. 1 bulb yield. Sweet corn var. Golden Bantum planted on May 15, 2012 at 435 days after fomesafen application was injured 40 to 92 percent compared to the grower standard (data not shown). The highest injury was observed from plants growing in plots previously treated with fomesafen at 0.5 lb ai/acre. Injury was characterized by midrib and vein chlorosis (whitening). The tissue between veins remained green/yellow, but on some plants the midrib was weakened and resulted in collapsed leaves. There also was an improper unfurling “buggy whipping” of the leaves. Injured plants did not recover. Plants within plots previously treated with fomesafen at 0.5 lb ai/acre eventually wilted and dried. Sweet corn was not taken to maturity due to excessive bird damage. Summary The results suggested that winter wheat var. Stephens and spring wheat (Alturas) could be safely planted in the Treasure Valley the fall and spring following fomesafen application, respectively. Similarly, pinto bean (Windbreaker) could be planted safely the spring following application of fomesafen. At the intended use rate of 0.25 lb ai/acre, onion could be safely planted the spring following application of fomesafen. However, the results suggested that sugar beet, sweet corn, and spring barley were sensitive to soil residue almost a year after fomesafen application. The registration of fomesafen will bring a new herbicide group for weed control in potato in the Treasure Valley. Use of different herbicide groups is recommended as a tactic to avoid selection for weed resistance to herbicides. If registered, growers are likely to experience better weed control by tank- mixing fomesafen with either Dual Magnum® (S-metolachlor) or Outlook® (dimethenamid-p) and Prowl® H2O (pendimethalin), which have become foundation products for weed control programs in potato. Better weed control produces higher quality potato, which in turn benefits growers, the processing industry, and consumers of this nutritious produce.


Table 2. Response of winter wheat var. Stephens to fomesafen (Reflex) herbicide soil residues 179 days after application to control weeds in potato at the Malheur Experiment Station, Ontario, OR, 2012.

Winter wheatb Application Injury Yield Treatmenta Rate Unit date Apr17, 2012 May 21, 2012 % cwt/acre Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 0.0 a 0.0 a 96.9 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Fomesafen (Reflex) 0.5 lb ai/a May 21, 2011 0.0 a 0.0 a 84.8 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Dual Magnum 1.27 lb ai/a May 21, 2011 0.0 a 0.0 a 93.3 a Prowl H2O 0.95 lb ai/a May 21, 2011 Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 Dual Magnum 1.27 lb ai/a May 21, 2011 0.0 a 0.0 a 82.9 a Prowl H2O 0.95 lb ai/a May 21, 2011 LSD (P = 0.05) -- -- NS Standard deviation -- -- 7.1

a Dual Magnum plus Prowl H2O was considered the grower standard treatment for weed control in potato. b Means within a column followed by the same number are not significantly different (LSD 0.05).


Table 3. Response of spring wheat var. Alturas to fomesafen (Reflex) herbicide soil residues 293 days after application to control weeds in potato at the Malheur Experiment Station, Ontario, OR, 2012.

Spring wheatb Application Injury Treatmenta Rate Unit date Apr 17, 2012 May 21, 2012 Yield --------------- % --------------- cwt/acre Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 0.0 a 0.0 a 64.9 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Fomesafen (Reflex) 0.5 lb ai/a May 21, 2011 0.0 a 0.0 a 73.3 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Dual Magnum 1.27 lb ai/a May 21, 2011 0.0 a 0.0 a 71.4 a Prowl H2O 0.95 lb ai/a May 21, 2011 Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 Dual Magnum 1.27 lb ai/a May 21, 2011 0.0 a 0.0 a 78.3 a Prowl H2O 0.95 lb ai/a May 21, 2011 LSD (P = 0.05) -- -- NS Standard deviation -- -- 7.9



Table 4. Response of pinto bean var. Windbreaker to fomesafen (Reflex) herbicide soil residues 360 days after application to control weeds in potato at the Malheur Experiment Station, Ontario, OR, 2012.

Pinto beanb Application Injury Treatmenta Rate Unit date Apr 17, 2012 May 21, 2012 Yield --------------- % --------------- lbs/acre Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 0 b 0 a 4,344 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Fomesafen (Reflex) 0.5 lb ai/a May 21, 2011 0 a 0 a 4,447 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Dual Magnum 1.27 lb ai/a May 21, 2011 0 a 0 a 4,178 a Prowl H2O 0.95 lb ai/a May 21, 2011 Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 Dual Magnum 1.27 lb ai/a May 21, 2011 0 a 0 a 3,545 a Prowl H2O 0.95 lb ai/a May 21, 2011 LSD (P = 0.05) -- -- NS Standard deviation -- -- 453



Table 5. Response of spring barley var. Millenium planted 293 days after fomesafen (Reflex) application to control weeds in potato at the Malheur Experiment Station, Ontario, OR, 2012.

Spring barleyb Application Injury Treatmenta Rate Unit date Apr 17, 2012 May 21, 2012 Yield --------------- % --------------- cwt/acre Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 48.3 b 13.3 b 54.8 ab Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Fomesafen (Reflex) 0.5 lb ai/a May 21, 2011 71.7 a 36.7 a 50.0 b Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Dual Magnum 1.27 lb ai/a May 21, 2011 60.0 ab 10.0 bc 49.4 b Prowl H2O 0.95 lb ai/a May 21, 2011 Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 Dual Magnum 1.27 lb ai/a May 21, 2011 0.0 c 0.0 c 63.5 a Prowl H2O 0.95 lb ai/a May 21, 2011 LSD (P = 0.05) 16.23 11.04 10.83 Standard deviation 8.12 5.53 5.42



Table 6. Response of sugar beet hybrid 27RR20 to fomesafen (Reflex) herbicide soil residues 324 days after application to control weeds in potato at the Malheur Experiment Station, Ontario, OR, 2012. Application Injury Sugar beet yieldb Treatmenta Rate Unit date Apr 17, 2012 May 21, 2012 Plant stand Root Yield Sugar content ERSc % roots/acre tons/acre % lb/acre Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 28.3 b 20.0 b 45,499 a 47.1 a 16.6 a 13,137.1 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Fomesafen (Reflex) 0.5 lb ai/a May 21, 2011 95.0 a 93.3 a 17,804 b 30.5 b 15.9 a 8,150.6 b Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Dual Magnum 1.27 lb ai/a May 21, 2011 13.3 bc 8.3 bc 45,103 a 46.3 a 16.8 a 13,184.0 a Prowl H2O 0.95 lb ai/a May 21, 2011 Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 Dual Magnum 1.27 lb ai/a May 21, 2011 0.0 c 0.0 c 4,9059 a 47.1 a 16.9 a 13,703.8 a Prowl H2O 0.95 lb ai/a May 21, 2011 LSD (P = 0.05) 15.9 16.9 8,167 4.7 NS 1,543.4 Standard deviation 7.9 8.5 4,088 2.4 0.6 772.5 a Dual Magnum plus Prowl H2O was considered the grower standard treatment for weed control in potato. b Means within a column followed by the same number are not significantly different (LSD 0.05). cERS = Estimated recoverable sugar.

Table 7. Response of dry bulb onion var. Vaquero to fomesafen (Reflex) herbicide soil residues 296 days after application to control weeds in potato at the Malheur Experiment Station, Ontario, OR, 2012. Application Onion yieldb Treatmenta Rate Unit date Injury Small Medium Jumbo Colossal U.S. No. 1 % ---------------------------------------------- cwt/acre ---------------------------------------- Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 2 b 17.1 a 96.0 b 513.5 a 23.7 a 633.2 a Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Fomesafen (Reflex) 0.5 lb ai/a May 21, 2011 92 a 8.7 a 45.2 b 195.1 b 8.7 a 249.0 b Clethodim (Select) 0.125 lb ai/a COC 1 % v/v Dual Magnum 1.27 lb ai/a May 21, 2011 0 b 16.1 a 157.9 a 546.4 a 3.1 a 707.4 a Prowl H2O 0.95 lb ai/a May 21, 2011 Fomesafen (Reflex) 0.25 lb ai/a May 21, 2011 Dual Magnum 1.27 lb ai/a May 21, 2011 0 b 22.9 a 171.4 a 434.3 ab 23.5 a 629.1 a Prowl H2O 0.95 lb ai/a May 21, 2011 LSD (P = 0.05) 3 NS 58.1 293.3 NS 304.81 Standard deviation 1.7 7.4 29.1 146.8 20.9 152.6 a Dual Magnum plus Prowl H2O was considered the grower standard treatment for weed control in potato. b Means within a column followed by the same number are not significantly different (LSD 0.05); Onion were graded to size as follows: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), U.S. No. 1 was composed of medium through colossal.

SWEET POTATO CULTIVAR PERFORMANCE AND IRRIGATION CRITERIA FOR THE TREASURE VALLEY Joel Felix, Clinton C. Shock, Joey Ishida, Eric B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012 Introduction Sweet potato is a long-season crop grown mainly in the southeastern United States and in California. The availability of irrigation water together with high temperatures during summer favors production of high quality sweet potatoes in eastern Oregon. Recently, growers have indicated interest in growing sweet potato as a new crop in eastern Oregon. The valley has a number of crop produce processors who may be willing to buy sweet potatoes grown locally as a strategy to cut the costs associated with sweet potato trucking from California and the southeastern United States. Purchasing locally produced sweet potatoes could significantly reduce the carbon footprint of sweet potato processors in the Treasure Valley. Also, growers would be able to develop niche marketing for a crop that is loved by most consumers. Newly developed sweet potato varieties will produce mature tubers in 80 to 90 days, suggesting that plants transplanted in early June can produce mature tubers, which could be harvested during September or early October, around the time of the first vegetation killing frost. Critical factors for successful sweet potato production include irrigation scheduling and the amount of water to be applied. Irrigation scheduling options rely on the measurement of soil water content or soil water tension. Precise irrigation scheduling by soil water tension criteria is a powerful method to optimize plant performance. By utilizing the ideal soil water tension and adjusting irrigation duration and amount, it is possible to simultaneously achieve high productivity and meet environmental stewardship goals for water use and reduced leaching (Shock and Wang 2011).

Objectives The overarching goal of this study was to assess the possibility of producing sweet potato in eastern Oregon. The specific objectives were to (1) evaluate varieties; (2) develop the irrigation criterion suitable for sweet potato production in eastern Oregon; and (3) evaluate the herbicide Dual Magnum® (S-metolachlor) for crop safety and weed efficacy under local conditions. The herbicide data will be used to support a Section 24C local needs registration of Dual Magnum for weed control under eastern Oregon conditions.

Materials and Methods Fields were plowed and disked during fall of 2010 and 2011 prior to trials conducted in 2011 and 2012. The field was fumigated on March 28, 2011 using metam sodium at 30 gal/acre through

Sweet Potato Cultivar Performance and Irrigation Criteria for the Treasure Valley 121

sprinklers, while in 2012 the field was fumigated using Telone® II at 20 gal/acre in the fall of 2011. The beds (36 inches wide) were formed 3 weeks after fumigation followed by fertilizer to supply 100 lb nitrogen/acre that was shanked into beds. Studies to accomplish objectives 1 and 2 followed a split-plot design with irrigation criteria as the main plots and varieties as the split-plots with treatments arranged in randomized complete block. Each split-plot was 3 beds (9 ft) wide by 30 ft long. The study for objective 3 followed a randomized complete block design. Each study had three replications and drip tape was used to deliver irrigation water. Sweet potato slips were transplanted by hand on June 3, 2011 and May 24, 2012 on 12-inch spacing within the row using the drip tape emitter spacing on top of the bed as markers. The drip tape used was Toro Aqua-traxx® (Toro Co., El Cajon, CA) 8-mil emitting 0.22 gal/min/100 ft. Slips were transplanted 4- to 6-inch depth using a hand trowel. Plants were immediately irrigated for 5 hours (0.35 inch) in 2011 and 8.5 hours (0.6 inch) in 2012 to provide water and soil/transplant contact. Plants were irrigated again on June 4, 2011 for 2 hours (0.14 inch) and May 29, 2012 for 22 hours (1.54 inch). Plants were irrigated again on June 10, 21 and July 5, 2011 to provide 0.5 inch of water each. Other irrigations in 2012 were on June 15 and 25 to provide 0.7 inch and 1.4 inch, respectively. Subsequent irrigations were automatically determined by the datalogger controller depending on targeted soil water tension criteria. The irrigation criteria in 2011 were 40, 60, 80, and 100 kPa of soil water tension (SWT) and water was delivered through drip tape. Because plants responded similarly to 80 and 100 kPa, the criteria in 2012 were changed to 25, 40, 60, and 80 kPa. All treatments in the herbicide evaluation study were irrigated at 25 kPa. Sweet potato plants in each main plot were irrigated automatically and independently when the SWT dropped below the targeted irrigation criterion. The irrigation duration was predetermined based on the drip tape capacity to deliver 0.5 inch of water in 7 hours and 5 min per event. Soil water tension was measured in each main plot with four granular matrix sensors (Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside, CA) centered at 8-inch depth in the center row of ‘Beauregard’ variety in each main plot. Sensors had been calibrated to local SWT (Shock et al. 1998). The granular metric sensors were connected to a datalogger (CR10X, Campbell Scientific, Logan, UT) through a multiplexer (AM 410 multiplexer, Campbell Scientific). The datalogger read the sensors and recorded the hourly SWT. The datalogger was programmed to check the sensor readings in each main plot every 12 hours and irrigate the appropriate main plot if the average SWT was below the targeted criterion. The irrigations were controlled by the datalogger using a controller (SDM CD16AC controller, Campbell Scientific) connected to solenoid valves in each main plot. The irrigation water was supplied by a well that maintained a continuous and constant water pressure of 241 kPa (35 psi). The pressure in the drip lines was maintained at 69 kPa (10 psi) by pressure regulators in each main plot. The automated irrigation system was started on July 8, 2011 and June 29, 2012 and was turned off on September 29, 2011 and October 1, 2012.

Integrated pest management Post-transplant soil-active herbicides were not used on the variety by irrigation criteria study because of the field proximity to sensitive crops. All plots were sprayed with glyphosate (Roundup® at 22 fl oz/acre) on May 26, 2011 and April 10, 2012 to control all emerged weeds prior to transplanting. Sethoxydim (Poast®) at 16 fl oz/acre plus nonionic surfactant (0.25% v/v) was applied on June 27, 2011 and June 19, 2012 to control grassy weeds. Plots were hand-


weeded on June 27 and July 28, 2011 and June 19, 2012 to remove all broadleaf weeds. Later weed cohorts were sparsely distributed and were periodically removed by hand. Sweet potato vines were flailed on October 4, 2011 and October 8, 2012 and roots were dug using a two-row digger set at 18-inch depth. Roots were picked by hand from the center row and later graded following California standards (May and Scheuerman 1998). In brief, the roots were graded based on California standards; U.S. No. 1 were of uniform size 1¾-3½ inches diameter and 3-9 inches long; U.S. No. 2 (mediums) included misshapen roots with a minimum diameter of 1½ inches; jumbo weighed more than 20 oz and was true to type. The data were subjected to analysis of variance using PROCGLM procedure in Statistical Analysis Software (SAS) and means compared using Fisher’s protected LSD 0.05.

Results and Discussion Irrigated trial results The average SWT increased with the increase in the targeted irrigation criterion (Table 1). The total amount of water applied from transplanting to harvest included the water used during the plant establishment phase (June 3 to July 8, 2011 and May 24 to June 25, 2012) and rainfall. Total applied water decreased with the increase in the targeted SWT. Plots irrigated at 25 kPa in 2012 received a total of 46.6 inches. That amount was significantly greater than the 40 kPa criteria that received a seasonal total of 14.1 inches and 33.9 inches of water in 2011 and 2012, respectively. Less water was used at 80 and 100 kPa. The difference in water used between 2011 and 2012 could be attributed to weather conditions (Fig. 1). Vegetative ground cover at 49 days after transplanting (July 22) was not influenced by the different irrigation criteria in 2011 (Table 2). Differences in average percent ground cover in 2011 were related to varietal characteristics. Ground cover for ‘Covington’ and ‘Diane’ averaged 80 and 83 percent, respectively, compared to 94 percent for Beauregard and ‘Evangeline’. These results are supported by the average runner length for different varieties on July 22 (Table 3). Covington and Diane had shorter vine length (29 and 26 inches) compared to Beauregard and Evangeline, which averaged 50 inches. Vine ground cover was influenced by the irrigation criteria and variety in 2012 (Table 2). The number of sweet potato vines per hill at 117 days after transplanting was similar among irrigation criteria in both years (Table 3). However, differences in the number of vines per hill were attributed to varieties. Covington and Beauregard averaged 8 and 9, 6 and 11 vines, compared to 11 and 12, 10 and 12 for Evangeline and Diane in 2011 and 2012, respectively. Potato vine length was influenced by irrigation and varied among varieties for both years, but there was no irrigation x variety interaction (Table 3). Beauregard produced the longest vines in both years. Sweet potato yield varied among irrigation criteria and varieties (Table 4). The greatest marketable yields were obtained when plants were irrigated at 40 kPa of SWT in 2011 and at 25 kPa in 2012. However, the irrigation at 25 kPa in 2012 reduced marketable yield for Diane and Evangeline. Generally, there was a decline in root yield with the increase in the targeted SWT to trigger irrigation. All varieties produced much lower yield at SWT of 80 and 100 kPa. Previous studies by May and Scheuerman (1998) in California indicated improved yield when sweet


potato were irrigated at 25 kPa throughout the season or 25 kPa during plant development and 100 kPa during root bulking stage. It is important to note that the irrigation criterion will be influenced by the soil type. Because the varieties responded similarly to irrigation at 80 and 100 kPa in 2011, the irrigation criteria was changed to 25, 40, 60, and 80 kPa in 2012. The water use efficiency (ton/acre marketable yield per inch of water applied) reflected the total amount of water used, which was directly related to the irrigation frequency needed to maintain the targeted irrigation criterion (Figs. 2 and 3).

Weed control results Application of Dual Magnum did not affect sweet potato plant stand (Table 5). The average number of hills ranged from about 12,000 to 15,000 per acre across the varieties. The marketable sweet potato root yield for plants treated with Dual Magnum at 1 to 1.27 lb ai/acre was similar to hand-weeded control. We believe the placement of water with drip irrigation may have reduced the weed pressure that would be expected with furrow or overhead irrigation.

Conclusions The results indicated that sweet potato could be grown successfully in eastern Oregon. Varietal differences in terms of growth habits and yield in response to available moisture were noted. Both Beauregard and Covington responded well to increased irrigation frequency and produced better yield in 2012 compared to 2011. Based on the combined results for 2011 and 2012, Beauregard and Covington were highly productive and should be irrigated at a SWT of 25 kPa.

References Shock, C., and F. Wang. 2011. Soil water tension, a powerful measurement for productivity and

stewardship. HortScience 46:178-185. Shock, C.C., J.M. Barnum, and M. Seddigh. 1998. Calibration of Watermark Soil Moisture

Sensors for irrigation management. Pages 139-146 in Proceedings of the International Irrigation Show, Irrigation Association, San Diego, CA.

May, D., and B. Scheuerman. 1998. Sweet potato production in California. Vegetable Research Information Center, Vegetable Production Series, Univ. Calif., Div. Agric. Natural Res. Publication 7237.


Table 1. Average hourly soil water tension, total water applied, marketable yield, and water use efficiency (ton/acre marketable yield per inch of water applied) averaged over four sweet potato varieties subjected to irrigation soil water tensions at the Malheur Experiment Station, Oregon State University, Ontario, OR, 2011 and 2012.

Soil water tension

Hourly soil water tension

Total water applieda

Marketable yield Water use efficiency

2011 2012 2011 2012 2011 2012 2011 2012 kPa kPa ------- inches -------- tons/acre tons/inch 25 -- 19.0 -- 46.6 -- 23.9 -- 0.52 40 27.7 27.2 14.1 33.9 17.9 24.6 0.12 0.84 60 44.4 35.4 10.1 14.9 15.5 17.8 0.15 1.19 80 48.6 55.2 6.3 11.1 10.0 15.7 0.16 1.46

100 58.9 -- 5.8 -- 9.6 -- 0.16 -- LSD (0.05) 4.2 10.8 1.6 6.4 1.3 3.2 0.02 0.54

a Total applied water for each criterion includes the amount applied uniformly to all treatments during plant establishment phase and rainfall from June 3 to September 29, 2011 and May 24 to October 8, 2012. Table 2. Sweet potato vegetative ground cover at 49 and 60 days after transplanting in 2011 and 2012 in response to differential irrigation criteria at Malheur Experiment Station, Oregon State University, Ontario, OR.

Ground cover

Irrigation criteria Covington Beauregard Evangeline Diane

2011 2012 2011 2012 2011 2012 2011 2012

kPa ---------------------------------------------------- % -------------------------------------------------

25 -- 100 -- 100 -- 100 -- 100

40 88 96 95 99 94 99 83 99

60 75 92 93 99 94 98 83 97

80 82 83 93 99 93 98 83 96

100 75 -- 94 -- 93 -- 80 --

LSD (0.05) NS 1 NS 1 NS 1 NS 1

Average 80 b 93 b 94 a 99 a 94 a 99 a 83 b 98 a


Table 3. Number of sweet potato vines per hill and average length (at 117 days after transplanting) in response to differential irrigation criteria and variety at the Malheur Experiment Station, 2011 and 2012.

Irrigation criterion Number of vines/hill

Covington Beauregard Evangeline Diane 2011 2012 2011 2012 2011 2012 2011 2012

(kPa) ------------------------------------------------- Number ------------------------------------------------ 25 -- 6 -- 11 -- 12 -- 14 40 6 6 9 11 9 10 11 13 60 6 6 9 11 10 10 12 10 80 13 6 10 10 12 10 12 9

100 5 -- 8 -- 11 -- 12 -- Average 8 6 9 11 11 10 12 12

LSD (0.05) Irrigation NS NS NS NS NS NS NS NS Varietya 3 2 3 2 3 2 3 2

Irrigation x Variety

NS NS NS NS NS NS NS NS

Irrigation criterion ----------------------------------- Average length/vine (inches) -----------------------------------

25 -- 67 -- 114 -- 91 -- 68 40 35 60 70 103 56 78 31 64 60 33 43 62 92 53 70 27 51 80 22 46 54 88 41 68 24 45

100 27 -- 49 -- 35 -- 20 -- Average 29 54 59 99 46 77 26 57

LSD (0.05) Irrigation 5 13 5 13 5 13 5 13 Variety 5 6 5 6 5 6 5 6

Irrigation x Variety

NS NS NS NS NS NS NS NS

a Comparing means within a row and year (LSD 0.05%).


Table 4. Sweet potato yield and grade in response to differential irrigation criteria and variety at Malheur Experiment Station, Oregon State University, Ontario, OR, 2011 and 2012.

Sweet potato yielda Irrigation Criterion

Total Marketable U. S. No. 2 U.S. No. 1 Jumbo Discard

2011 2012 2011 2012 2011 2012 2011 2012 2011 2012 2011 2012 (kPa) --------------------------------------------------- (tons/acre) -----------------------------------------------------

Beauregard 25 -- 38 -- 35 -- 8 -- 11 -- 16 -- 3 40 25 32 22 29 4 7 15 11 2 11 3 4 60 23 27 21 23 4 8 15 9 2 6 2 4 80 18 24 14 20 3 7 10 8 2 5 3 4

100 15 -- 12 -- 3 -- 9 -- 0 -- 3 -- Average 20 30 17 27 4 8 12 10 2 9 3 4

Covington 25 -- 30 -- 25 -- 10 -- 7 -- 8 -- 5 40 25 25 18 19 7 10 11 7 0 2 7 6 60 20 19 14 13 6 8 8 4 0 2 6 6 80 16 17 7 12 4 7 3 4 0 2 8 6

100 15 -- 7 -- 3 -- 4 -- 0 -- 8 -- Average 19 23 12 17 5 8 6 5 0 3 7 6

Diane 25 -- 22 -- 15 -- 8 -- 5 -- 2 -- 8 40 23 23 19 19 2 8 16 7 1 4 4 4 60 19 21 17 18 2 6 14 6 1 6 2 3 80 16 19 13 15 3 6 10 7 1 3 3 4

100 15 -- 13 -- 2 -- 9 -- 1 -- 2 -- Average 18 21 16 17 2 7 12 6 1 3

Evangeline 25 -- 26 -- 22 -- 7 -- 8 -- 7 -- 5 40 22 36 19 32 3 7 14 9 1 15 3 4 60 19 20 16 17 3 6 12 7 1 4 3 3 80 13 20 9 16 3 6 6 6 1 4 3 4

100 13 -- 10 -- 2 -- 6 -- 1 -- 3 -- Average 17 26 14 22 3 7 10 8 1 3 4

LSD (0.05) Irrigation 1 2 1 3 1 1 1 1 1 3 1 1

Variety 1 3 1 3 1 1 1 1 1 3 1 1 Irrigation X Variety

NS 6 NS 6 1 2 NS 2 NS 7 NS 2

a Sweet potato grades were based on California standards; U.S. No. 1 were of uniform size 1¾-3½ inches diameter and 3-9 inches long; U.S. No. 2 (mediums) included misshapen and with a minimum diameter of 1½ inches; jumbo weighed more than 20 oz and were true to type. Discarded roots were <1½ inches in diameter. Marketable yield was comprised of U.S. No. 2, U.S. No. 1, and jumbo root categories.


Table 5. Response of five sweet potato varieties to Dual Magnum herbicide applied 7 days after transplanting at the Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Sweet potato yielda Herbicide

rate Plant stand

Discard U.S. No. 2

U.S. No. 1

Jumbo Marketable

lb ai/acre hills/acre -------------------------- tons/acre -------------------------- Beauregard Hand weeded 0.00 14,520 3.7 6.7 11.0 18.3 36.0 Dual Magnum 0.95 13,262 4.5 8.7 10.4 8.3 27.3 Dual Magnum 1.27 13,262 3.8 7.6 11.6 11.7 30.9 Covington Hand weeded 0.00 14,230 4.5 7.5 9.8 6.3 23.6 Dual Magnum 0.95 13,842 5.3 8.8 7.7 2.5 18.9 Dual Magnum 1.27 14,230 5.6 7.4 9.1 3.4 19.9 Diane Hand weeded 0.00 12,294 7.4 8.1 6.6 4.3 19.0 Dual Magnum 0.95 12,584 6.6 8.5 7.3 2.8 18.6 Dual Magnum 1.27 11,906 8.3 7.1 6.9 4.1 18.1 Evangeline Hand weeded 0.00 14,520 4.8 7.2 8.9 6.4 22.5 Dual Magnum 0.95 12,874 4.6 6.8 7.2 8.0 22.1 Dual Magnum 1.27 13,552 4.9 4.1 5.7 7.4 17.1 LSD (0.05) NS 2.9 2.6 3.3 6.1 NS

a Sweet potato grades were based on California standards; U.S. No. 1 were of uniform size 1¾-3½ inches diameter and 3-9 inches long; U.S. No. 2 (mediums) included misshapen and with a minimum diameter of 1½ inches; jumbo weighed more than 20 oz and were true to type. Discarded roots were <1½ inches in diameter. Marketable yield was comprised of U.S. No. 2, U.S. No. 1, and jumbo root categories.


Figure 1. Cumulative growing degree-days (base 50°F) and mean air temperature at the Malheur Experiment Station, Oregon State University, Ontario, OR, 2011 and 2012.

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Figure 3. Soil water tension at 8-inch depth over time for sweet potato production at Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Each peak represents 0.5 inch of water delivered by drip irrigation with different irrigation criteria.

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DIRECT SURFACE SEEDING STRATEGIES FOR THE ESTABLISHMENT OF TWO NATIVE LEGUMES OF THE INTERMOUNTAIN WEST Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012 Doug Johnson and Shaun Bushman, USDA Agricultural Research Service, Logan, UT

Introduction Legumes provide an important role for restored rangelands of the Intermountain West. Reliable commercial seed production is desirable to make seed readily available. Direct seeding of native range plants has been generally problematic, especially for certain species. Rangeland legumes have been extremely difficult to establish.

In established native perennial fields at the Malheur Experiment Station and in rangelands we have observed prolific natural emergence from seed that falls on the soil surface and is covered by thin layers of organic debris. Seed of some legumes has a hard seed coat that slows germination. Scarification of the seed coat might improve water penetration and improve emergence. Fall planting is important for many native plant species, because their seed requires a period of cold to break dormancy (vernalization). Loss of soil moisture, soil crusting, and bird damage are some detrimental factors hindering emergence of fall planted seed. Row cover can be a protective barrier against soil desiccation and bird damage. Seed treatment can protect the emerging seed from fungal pathogens that might cause seed decomposition or seedling damping off. This trial tested the effect of timing of planting (fall vs. spring), seed scarification, row cover, and seed treatment on germination of surface-planted seed of two legume species, blue mountain prairie clover (Dalea ornata) and basalt milkvetch (Astragalus filipes) that are native to Malheur County and surrounding rangelands for which stand establishment has been problematic. Materials and Methods Two selected germplasms of blue mountain prairie clover, ‘Majestic’ and ‘Spectrum’, and one accession of basalt milkvetch were included in the stand establishment trials. One seed lot of each of these three plant materials was scarified by immersion for 5 min in 98 percent sulfuric acid. After scarification, 12 seed packets of each seed lot were prepared with 120 seeds per packet. Seed of half of the scarified and half of the nonscarified packets was treated briefly with a liquid mix of the fungicides Allegiance (metalaxyl) and captan (100 g Allegiance, 100 g captan in 1 liter of water) then dried. The seed packets were assigned to one of six treatments (Tables 1-3). Seed was planted manually on November 11, 2011 and again on February 28, 2012. Immediately before the spring 2012 planting, a manual clodbuster was run over the surface of the beds to break the crust formed over the winter. The experimental design was a randomized

Direct Surface Seeding Strategies for the Establishment of Two Native Legumes of the Intermountain West 132

complete block with four replications. Plots were one 30-inch-wide by 5-ft-long bed. Each plot had 120 seeds planted in 5 ft of 2 rows on the bed.

After planting, some of the beds were covered with row cover. The row cover (N-sulate, DeWitt Co., Inc., Sikeston, MO) covered four rows (two beds) and was applied with a mechanical plastic mulch layer.

On March 12, 2012, the row cover was removed and emergence counts were made in each plot. Emergence counts were again taken on March 22, April 2, April 12, April 24, and May 8. The row cover for the fall planted seed was replaced after the March 12 count. The row cover for the spring planted seed was replaced after the March 12 and March 22 counts. Tetrazolium tests were conducted to determine seed viability of each species. Seed viability was 89 percent for unscarified and 91percent for scarified Dalea ornata (cv. Spectrum, 2010), 88 percent for unscarified and 92 percent for scarified Dalea ornata (cv. Majestic, 2009), and 97 percent for unscarified and 95 percent for scarified Astragalus filipes (Lot No. NBR-1 2010). The tetrazolium results were used to correct the emergence data to emergence of viable seed.

Data were analyzed using analysis of variance (General Linear Models Procedure, NCSS, Kaysville, UT). Means separation was determined using Fisher’s least significant difference test at the 5 percent probability level, LSD (0.05). Results and Discussion The winter of 2011/2012 at the Malheur Experiment Station had no snowfall compared to the 68-year winter (Oct-Mar) average of 18 inches. Snow cover may reduce fluctuations in temperature and moisture and thus may be an important factor in vernalization of surface-planted seed. Precipitation from October 2011 through March 2012 (6.1 inches) was close to the 68-year average of 6.4 inches. Dalea ornata Emergence and stand for both D. ornata selected germplasms was very poor for the fall-planted seed for all treatments (Tables 1 and 2). There were no statistically significant differences in stand between treatments for the fall-planted seed. Emergence and stand for the spring-planted seed was significantly better than for the fall-planted seed, but was nevertheless poor. The highest stand for the spring-planted seed was achieved with row cover and scarified seed with no fungicide (24% for Spectrum and 34.7% for Majestic). For the spring-planted seed, row cover resulted in significantly higher stand than uncovered seed for both germplasms. Scarified seed resulted in significantly higher stand than non-scarified seed for both germplasms. Seed treatment resulted in lower stand than untreated seed for both germplasms. Astragalus filipes Fall planting resulted in higher stand than spring-planted seed (Table 3). Emergence and stand for the fall-planted seed was nevertheless poor. The highest stand for the fall planted seed was achieved with row cover and scarified, untreated seed (36.2%). For the fall-planted seed, row cover resulted in significantly higher stand than uncovered seed. Scarified seed resulted in


significantly higher stand than nonscarified seed. Seed treatment resulted in lower stand than untreated seed. Conclusions Stand survivability was very poor for both species. By May 8, stand was 10 percent or less for all treatments and both germplasms of D. ornata and 12 percent or less for all treatments of A. filipes.


Table 1. Stand of Dalea ornata (Majestic selected germplasm) in response to timing of planting and three treatments. Oregon State University, Malheur Experiment Station, Ontario, OR. Stand counts were based on live plants as a percent of live seed planted. Timing Row cover Scarification Seed treatment 12 Mar 22 Mar 2 Apr 12 Apr 24 Apr 8 May

------------------------ % stand -------------------------

Fall 2011 no no no 0.00 0.24 0.24 0.00 0.00 0.00

no no yes 0.00 0.00 0.00 0.00 0.00 0.00

no avg 0.00 0.12 0.12 0.00 0.00 0.00

no yes no 0.00 0.00 0.00 0.23 0.00 0.00

no yes yes 0.00 0.00 0.23 0.45 0.00 0.00

no avg 0.00 0.00 0.11 0.34 0.00 0.00

avg 0.00 0.06 0.12 0.17 0.00 0.00

yes no no 3.31 0.00 0.95 0.71 0.00 0.47

yes no yes 2.37 0.24 0.47 1.89 0.00 0.24

yes avg 2.84 0.12 0.71 1.30 0.00 0.36

yes yes no 1.81 0.91 0.91 0.91 0.00 0.00

yes yes yes 4.08 1.59 1.59 0.68 0.23 0.23

yes avg 2.94 1.25 1.25 0.79 0.11 0.11

avg 2.89 0.68 0.98 1.05 0.06 0.23

avg 1.45 0.37 0.55 0.61 0.03 0.12 Spring 2012 no no no 0.00 0.00 0.71 0.24 0.47 0.00

no no yes 0.00 0.00 0.00 0.47 1.18 0.00

no avg 0.00 0.00 0.36 0.36 0.83 0.00

no yes no 0.00 1.59 8.38 12.23 3.85 3.17

no yes yes 0.00 0.00 1.13 6.57 3.17 2.72

no avg 0.00 0.79 4.76 9.40 3.51 2.94

avg 0.00 0.40 2.56 4.88 2.17 1.47

yes no no 0.00 2.60 3.08 3.79 2.84 0.24

yes no yes 0.00 0.24 0.24 0.24 0.00 0.24

yes avg 0.00 1.42 1.66 2.01 1.42 0.24

yes yes no 0.00 33.97 34.65 22.87 17.66 5.89

yes yes yes 0.00 2.94 7.02 14.49 0.45 0.23

yes avg 0.00 18.46 20.83 18.68 9.06 3.06

avg 0.00 9.94 11.25 10.35 5.24 1.65

avg 0.00 5.17 6.90 7.61 3.70 1.56 LSD (0.05)

Species X timing 2.92 2.55 2.48 2.02 2.21 1.27 Species X timing X row cover 4.13 3.60 3.51 2.86 3.13 NS Species X timing X row cover X scarification 1.49 3.85 4.19 NS 2.81 NS Species X timing X row cover X scarif. X seed treatment 4.71 7.98 5.41 NS 2.38 NS

Table 2. Stand of Dalea ornata (Spectrum selected germplasm) in response to timing of planting and three treatments. Oregon State University, Malheur Experiment Station, Ontario, OR. Stand counts were based on live plants as a percent of live seed planted. Timing Row cover Scarification Seed treatment 12 Mar 22 Mar 2 Apr 12 Apr 24 Apr 8 May

------------------------ % stand -------------------------

Fall 2011 no no no 0.00 0.00 0.00 0.23 0.23 0.00

no no yes 0.00 0.00 0.00 0.47 0.00 0.00

no avg 0.00 0.00 0.00 0.35 0.12 0.00

no yes no 0.00 0.23 0.00 0.23 0.00 0.00

no yes yes 0.00 0.00 0.00 0.23 0.00 0.00

no avg 0.00 0.11 0.00 0.23 0.00 0.00

avg 0.00 0.06 0.00 0.29 0.06 0.00

yes no no 3.75 0.23 2.81 1.87 0.23 0.70

yes no yes 3.51 0.70 2.57 4.45 2.11 2.34

yes avg 3.63 0.47 2.69 3.16 1.17 1.52

yes yes no 3.21 0.69 1.14 1.37 0.23 0.23

yes yes yes 4.35 0.23 1.14 1.37 0.00 0.00

yes avg 3.78 0.46 1.14 1.37 0.11 0.11

avg 3.70 0.46 1.92 2.27 0.64 0.82


no no yes 0.00 0.00 0.00 0.47 0.70 0.23

no avg 0.00 0.00 0.23 1.52 0.94 0.23

no yes no 0.00 0.00 2.98 6.87 5.95 2.29

no yes yes 0.00 0.00 0.00 0.23 0.00 0.69

no avg 0.00 0.00 1.49 3.55 2.98 1.49

avg 0.00 0.00 0.86 2.54 1.96 0.86

yes no no 0.00 2.11 0.94 2.11 1.87 0.47

yes no yes 0.00 0.00 1.40 3.51 0.94 0.47

yes avg 0.00 1.05 1.17 2.81 1.40 0.47

yes yes no 0.00 16.48 24.04 16.94 11.68 3.89

yes yes yes 0.00 0.00 2.75 4.35 1.60 1.14

yes avg 0.00 8.24 13.39 10.65 6.64 2.52

avg 0.00 4.65 7.28 6.73 4.02 1.49

avg 0.00 2.32 4.07 4.63 2.99 1.18 LSD (0.05)


Table 3. Stand of Astragalus filipes in response to timing of planting and three treatments. Oregon State University, Malheur Experiment Station, Ontario, OR. Stand counts were based on live plants as a percent of live seed planted. Timing Row cover Scarification Seed treatment 12 Mar 22 Mar 2 Apr 12 Apr 24 Apr 8 May

------------------------- % stand -------------------------

Fall 2011 no no no 0.00 0.43 0.00 0.64 0.64 0.64

no no yes 0.00 0.21 0.21 0.43 0.00 0.21

no avg 0.00 0.32 0.11 0.54 0.32 0.43

no yes no 0.00 4.17 1.10 2.41 3.07 2.41

no yes yes 0.44 3.51 0.22 2.41 2.19 0.66

no avg 0.22 3.84 0.66 2.41 2.63 1.54

avg 0.11 2.08 0.38 1.47 1.48 0.98

yes no no 13.75 12.03 9.24 8.81 4.30 4.08

yes no yes 5.58 8.38 2.36 4.08 2.36 0.43

yes avg 9.66 10.20 5.80 6.44 3.33 2.26

yes yes no 29.82 36.18 28.29 24.78 17.54 11.40

yes yes yes 14.91 14.91 8.99 8.99 5.04 5.04

yes avg 22.37 25.55 18.64 16.89 11.29 8.22

avg 16.02 17.88 12.22 11.66 7.31 5.24


no no yes 0.00 0.00 0.00 0.00 0.00 0.00

no avg 0.00 0.00 0.00 0.21 0.32 0.00

no yes no 0.00 0.00 0.00 0.44 0.22 1.10

no yes yes 0.00 0.00 0.00 0.44 0.88 0.88

no avg 0.00 0.00 0.00 0.44 0.55 0.99

avg 0.00 0.00 0.00 0.33 0.44 0.49

yes no no 0.00 0.00 0.21 2.58 1.72 1.07

yes no yes 0.00 0.21 0.00 0.86 0.21 0.21

yes avg 0.00 0.11 0.11 1.72 0.97 0.64

yes yes no 0.00 1.32 4.82 14.25 3.07 2.85

yes yes yes 0.00 0.22 1.32 3.29 0.44 0.66

yes avg 0.00 0.77 3.07 8.77 1.75 1.75

avg 0.00 0.44 1.59 5.25 1.36 1.20

avg 0.00 0.22 0.79 2.79 0.90 0.85 LSD (0.05)


EIGHT YEARS EVALUATING THE IRRIGATION REQUIREMENTS FOR NATIVE WILDFLOWER SEED PRODUCTION Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Nancy Shaw, U.S. Forest Service, Rocky Mountain Research Station, Boise, ID

Ram S. Sampangi, University of Idaho, Parma, ID Introduction Native wildflower seed is needed to restore rangelands of the Intermountain West. Commercial seed production is necessary to provide the quantity of seed needed for restoration efforts. A major limitation to economically viable commercial production of native wildflower (forb) seed is stable and consistent seed productivity over years.

In native rangelands, the natural variations in spring rainfall and soil moisture result in highly unpredictable water stress at flowering, seed set, and seed development, which for other seed crops is known to compromise seed yield and quality.

Native wildflower plants are not well adapted to croplands. They often are not competitive with crop weeds in cultivated fields. Poor competitiveness with weeds could also limit wildflower seed production. Both sprinkler and furrow irrigation could provide supplemental water for seed production, but these irrigation systems risk further encouraging weeds. Also, sprinkler and furrow irrigation can lead to the loss of plant stand and seed production due to fungal pathogens. By burying drip tapes at 12-inch depth and avoiding wetting the soil surface, we hoped to assure flowering and seed set without undue encouragement of weeds or opportunistic diseases. The trials reported here tested the effects of three low rates of irrigation on the seed yield of 13 native wildflower species. Materials and Methods Plant Establishment Seed of seven Intermountain West wildflower species (the first seven species in Table 1) was received in late November in 2004 from the Rocky Mountain Research Station (Boise, ID). The plan was to plant the seed in the fall of 2004, but due to excessive rainfall in October, the ground preparation was not completed and planting was postponed to early 2005. To try to ensure germination, the seed was submitted to cold stratification. The seed was soaked overnight in

Eight Years Evaluating the Irrigation Requirements for Native Wildflower Seed Production 138

distilled water on January 26, 2005, after which the water was drained and the seed soaked for 20 min in a 10 percent by volume solution of 13 percent bleach in distilled water. The water was drained and the seed was placed in thin layers in plastic containers. The plastic containers had lids with holes drilled in them to allow air movement. These containers were placed in a cooler set at approximately 34°F. Every few days the seed was mixed and, if necessary, distilled water added to maintain seed moisture. In late February, seed of Lomatium grayi and L. triternatum (see Table 1 for common names) had started to sprout.

In late February, 2005 drip tape (T-Tape TSX 515-16-340) was buried at 12-inch depth between two 30-inch rows of a Nyssa silt loam with a pH of 8.3 and 1.1 percent organic matter. The drip tape was buried in alternating inter-row spaces (5 ft apart). The flow rate for the drip tape was 0.34 gal/min/100 ft at 8 psi with emitters spaced 16 inches apart, resulting in a water application rate of 0.066 inch/hour.

On March 3, seed of all species was planted in 30-inch rows using a custom-made plot grain drill with disc openers. All seed was planted at 20-30 seeds/ft of row. The Eriogonum umbellatum and the Penstemon spp. were planted at 0.25-inch depth and the Lomatium spp. at 0.5-inch depth. The trial was irrigated with a minisprinkler system (R10 Turbo Rotator, Nelson Irrigation Corp., Walla Walla, WA) for even stand establishment from March 4 to April 29. Risers were spaced 25 ft apart along the flexible polyethylene hose laterals that were spaced 30 ft apart and the water application rate was 0.10 inch/hour. A total of 1.72 inches of water was applied with the minisprinkler system. Eriogonum umbellatum, Lomatium triternatum, and L. grayi started emerging on March 29. All other species except L. dissectum emerged by late April. Starting June 24, the field was irrigated with the drip system. A total of 3.73 inches of water was applied with the drip system from June 24 to July 7. The field was not irrigated further in 2005.

Plant stands for Eriogonum umbellatum, Penstemon spp., Lomatium triternatum, and L. grayi were uneven. Lomatium dissectum did not emerge. None of the species flowered in 2005. In early October, 2005 more seed was received from the Rocky Mountain Research Station for replanting. The empty lengths of row were replanted by hand in the E. umbellatum and Penstemon spp. plots. The Lomatium spp. plots had the entire row lengths replanted using the planter. The seed was replanted on October 26, 2005. In the spring of 2006, the plant stands of the replanted species were excellent, except for P. deustus.

On April 11, 2006 seed of three globemallow species (Sphaeralcea parvifolia, S. grossulariifolia, S. coccinea), two prairie clover species (Dalea searlsiae, D. ornata), and basalt milkvetch (Astragalus filipes) was planted at 30 seeds/ft of row. The field was sprinkler irrigated until emergence. Emergence was poor. In late August of 2006 seed of the three globemallow species was harvested by hand. On November 9, 2006 the six wildflowers that were planted in 2006 were mechanically flailed and on November 10, they were replanted. On November 11, the Penstemon deustus plots were also replanted at 30 seeds/ft of row.


Table 1. Wildflower species planted in the drip irrigation trials at the Malheur Experiment Station, Oregon State University, Ontario, OR.

Species Common names Eriogonum umbellatum Sulphur-flower buckwheat Penstemon acuminatus Sharpleaf penstemon, sand-dune penstemon Penstemon deustus Scabland penstemon, hotrock penstemon Penstemon speciosus Royal penstemon, sagebrush penstemon Lomatium dissectum Fernleaf biscuitroot Lomatium triternatum Nineleaf biscuitroot, nineleaf desert parsley Lomatium grayi Gray’s biscuitroot, Gray’s lomatium Sphaeralcea parvifolia Smallflower globemallow Sphaeralcea grossulariifolia Gooseberryleaf globemallow Sphaeralcea coccinea Scarlet globemallow, red globemallow Dalea searlsiae Searls’ prairie clover Dalea ornata Western prairie clover, Blue Mountain prairie clover Astragalus filipes Basalt milkvetch

Irrigation for Seed Production In April, 2006 each planted strip of each wildflower species was divided into plots 30 ft long. Each plot contained four rows of each species. The experimental designs were randomized complete blocks with four replicates. The three irrigation treatments were a nonirrigated check, 1 inch per irrigation, and 2 inches per irrigation. Each treatment received 4 irrigations that were applied approximately every 2 weeks starting with flowering of the wildflowers. The amount of water applied to each treatment was calculated by the length of time necessary to deliver 1 or 2 inches through the drip system. Irrigations were regulated with a controller and solenoid valves. After each irrigation, the amount of water applied was read on a water meter and recorded to ensure correct water applications.

In March of 2007, the drip-irrigation system was modified to allow separate irrigation of the species due to different timings of flowering. The three Lomatium spp. were irrigated together and Penstemon deustus and P. speciosus were irrigated together, but separately from the others. Penstemon acuminatus and Eriogonum umbellatum were irrigated individually. In early April, 2007 the three globemallow species, two prairie clover species, and basalt milkvetch were divided into plots with a drip-irrigation system to allow the same irrigation treatments that were received by the other wildflowers.

Irrigation dates are found in Table 2. In 2007, irrigation treatments were inadvertently continued after the fourth irrigation. Irrigation treatments for all species were continued until the last irrigation on June 24, 2007.

Soil volumetric water content was measured by neutron probe. The neutron probe was calibrated by taking soil samples and probe readings at 8-, 20-, and 32-inch depths during installation of the access tubes. The soil water content was determined volumetrically from the soil samples and


regressed against the neutron probe readings separately for each soil depth. Regression equations were then used to transform the neutron probe readings into volumetric soil water content.

Flowering, Harvesting, and Seed Cleaning Flowering dates for each species were recorded (Table 2). The Eriogonum umbellatum and Penstemon spp. plots produced seed in 2006, in part because they had emerged in the spring of 2005. Each year, the middle two rows of each plot were harvested when seed of each species was mature (Table 2), using the methods listed in Table 3. The plant stand for P. deustus was too poor to result in reliable seed yield estimates. Replanting of P. deustus in the fall of 2006 did not result in adequate plant stand in the spring of 2007.

Eriogonum umbellatum seeds did not separate from the flowering structures in the combine; the unthreshed seed was taken to the U.S. Forest Service Lucky Peak Nursery (Boise, ID) and run through a dewinger to separate seed. The seed was further cleaned in a small clipper seed cleaner.

Penstemon deustus seed pods were too hard to be opened in the combine; the unthreshed seed was precleaned in a small clipper seed cleaner and then seed pods were broken manually by rubbing the pods on a ribbed rubber mat. The seed was then cleaned again in the small clipper seed cleaner.

Penstemon acuminatus and P. speciosus were threshed in the combine and the seed was further cleaned using a small clipper seed cleaner.

Cultural Practices in 2006 On October 27, 2006, 50 lb phosphorus (P)/acre and 2 lb zinc (Zn)/acre were injected through the drip tape to all plots of Eriogonum umbellatum, Penstemon spp., and Lomatium spp. On November 11, 100 lb nitrogen (N)/acre as urea was broadcast to all Lomatium spp. plots. On November 17, all plots of Eriogonum umbellatum, Penstemon spp. (except P. deustus), and Lomatium spp. had Prowl® at 1 lb ai/acre broadcast on the soil surface. Irrigations for all species were initiated on May 19 and terminated on June 30. Harvesting and seed cleaning methods for each species are listed in Table 3.

Cultural Practices in 2007 Penstemon acuminatus and P. speciosus were sprayed with Aza-Direct® at 0.0062 lb ai/acre on May 14 and 29 for lygus bug control. Irrigations for each species were initiated and terminated on different dates (Table 2). Harvesting and seed cleaning methods for each species are listed in Table 3. All plots of the Sphaeralcea spp. were flailed on November 8, 2007.

Cultural Practices in 2008 On November 9, 2007 and on April 15, 2008, Prowl at 1 lb ai/acre was broadcast on all plots for weed control. Capture® 2EC at 0.1 lb ai/acre was sprayed on all plots of Penstemon acuminatus and P. speciosus on May 20 for lygus bug control. Irrigations for each species were initiated and terminated on different dates (Table 2). Harvesting and seed cleaning methods for each species are listed in Table 3.


Cultural Practices in 2009 On March18, Prowl at 1 lb ai/acre and Volunteer® at 8 oz/acre were broadcast on all plots for weed control. On April 9, 50 lb N/acre and 10 lb P/acre were applied through the drip irrigation system to the three Lomatium spp.

The flowering, irrigation timing, and harvest timing were recorded for each species (Table 2). Harvesting and seed cleaning methods for each species are listed in Table 3. On December 4, 2009, Prowl at 1 lb ai/acre was broadcast for weed control on all plots.

Cultural Practices in 2010 The flowering, irrigation, and harvest timing of the established wildflowers were recorded for each species (Table 2). Harvesting and seed cleaning methods for each species are listed in Table 3. On November 17, Prowl at 1 lb ai/acre was broadcast on all plots for weed control.

Cultural Practices in 2011

On May 3, 2011, 50 lb N/acre was applied to all Lomatium spp. plots as Uran (urea ammonium nitrate) injected through the drip tape. The timing of flowering, irrigations, and harvests varied by species (Table 2). Harvesting and seed cleaning methods for each species are listed in Table 3. On November 9, Prowl at 1 lb ai/acre was broadcast on all plots for weed control.


The soil volumetric water content was very low in 2012 prior to the onset of irrigation for each species. Iron deficiency symptoms were prevalent in 2012. On April 13, 50 lb N/acre, 10 lb P/acre, and 5 lb iron (Fe)/acre was applied to all Lomatium spp. plots as liquid fertilizer injected through the drip tape.


Table 2. Native wildflower flowering, irrigation, and seed harvest dates by species in 2006-2012, Malheur Experiment Station, Oregon State University, Ontario, OR.

Flowering Irrigation Species Start Peak End Start End Harvest 2006 Eriogonum umbellatum 19-May 20-Jul 19-May 30-Jun 3-Aug Penstemon acuminatus 2-May 10-May 19-May 19-May 30-Jun 7-Jul Penstemon deustus 10-May 19-May 30-May 19-May 30-Jun 4-Aug Penstemon speciosus 10-May 19-May 30-May 19-May 30-Jun 13-Jul Lomatium dissectum 19-May 30-Jun Lomatium triternatum 19-May 30-Jun Lomatium grayi 19-May 30-Jun Sphaeralcea parvifolia S. grossulariifolia Sphaeralcea coccinea Dalea searlsiae Dalea ornata 2007 Eriogonum umbellatum 25-May 25-Jul 2-May 24-Jun 31-Jul Penstemon acuminatus 19-Apr 25-May 19-Apr 24-Jun 9-Jul Penstemon deustus 5-May 25-May 25-Jun 19-Apr 24-Jun Penstemon speciosus 5-May 25-May 25-Jun 19-Apr 24-Jun 23-Jul Lomatium dissectum 5-Apr 24-Jun Lomatium triternatum 25-Apr 1-Jun 5-Apr 24-Jun 29-Jun, 16-Jul Lomatium grayi 5-Apr 10-May 5-Apr 24-Jun 30-May, 29-Jun Sphaeralcea parvifolia 5-May 25-May 16-May 24-Jun 20-Jun, 10-Jul, 13-Aug S. grossulariifolia 5-May 25-May 16-May 24-Jun 20-Jun, 10-Jul, 13-Aug Sphaeralcea coccinea 5-May 25-May 16-May 24-Jun 20-Jun, 10-Jul, 13-Aug Dalea searlsiae 20-Jun, 10-Jul Dalea ornata 20-Jun, 10-Jul 2008 Eriogonum umbellatum 5-Jun 19-Jun 20-Jul 15-May 24-Jun 24-Jul Penstemon acuminatus 29-Apr 5-Jun 29-Apr 11-Jun 11-Jul Penstemon deustus 5-May 20-Jun 29-Apr 11-Jun Penstemon speciosus 5-May 20-Jun 29-Apr 11-Jun 17-Jul Lomatium dissectum 10-Apr 29-May Lomatium triternatum 25-Apr 5-Jun 10-Apr 29-May 3-Jul Lomatium grayi 25-Mar 15-May 10-Apr 29-May 30-May, 19-Jun Sphaeralcea parvifolia 5-May 15-Jun 15-May 24-Jun 21-Jul S. grossulariifolia 5-May 15-Jun 15-May 24-Jun 21-Jul Sphaeralcea coccinea 5-May 15-Jun 15-May 24-Jun 21-Jul Dalea searlsiae 19-Jun Dalea ornata 19-Jun


Table 2, continued. Native wildflower flowering, irrigation, and seed harvest dates by species in 2006-2012. Malheur Experiment Station, Oregon State University, Ontario, OR. Flowering Irrigation Species start peak end start end Harvest 2009

Eriogonum umbellatum 31-May 15-Jul 19-May 24-Jun 28-Jul Penstemon acuminatus 2-May 10-Jun 8-May 12-Jun 10-Jul Penstemon deustus 19-May 24-Jun Penstemon speciosus 14-May 20-Jun 19-May 24-Jun 10-Jul Lomatium dissectum 10-Apr 7-May 20-Apr 28-May 16-Jun Lomatium triternatum 10-Apr 7-May 1-Jun 20-Apr 28-May 26-Jun Lomatium grayi 10-Mar 7-May 20-Apr 28-May 16-Jun Sphaeralcea parvifolia 1-May 10-Jun 22-May 24-Jun 14-Jul Sphaeralcea grossulariifolia 1-May 10-Jun 22-May 24-Jun 14-Jul Sphaeralcea coccinea 1-May 10-Jun 22-May 24-Jun 14-Jul

2010 Eriogonum umbellatum 4-Jun 12-19 Jun 15-Jul

28-May 8-Jul 27-Jul

Penstemon speciosus 14-May

20-Jun

12-May 22-Jun 22-Jul Lomatium dissectum 25-Apr

20-May

15-Apr 28-May 21-Jun

Lomatium triternatum 25-Apr

15-Jun

15-Apr 28-May 22-Jul Lomatium grayi 15-Mar

15-May

15-Apr 28-May 22-Jun

Sphaeralcea parvifolia 10-May 4-Jun 25-Jun

28-May 8-Jul 20-Jul Sphaeralcea grossulariifolia 10-May 4-Jun 25-Jun

28-May 8-Jul 20-Jul

Sphaeralcea coccinea 10-May 4-Jun 25-Jun 28-May 8-Jul 20-Jul

2011

Eriogonum umbellatum 8-Jun 30-Jun 20-Jul

20-May 5-Jul 1-Aug Penstemon speciosus 25-May 30-May 30-Jun

20-May 5-Jul 29-Jul

Lomatium dissectum 8-Apr 25-Apr 10-May

21-Apr 7-Jun 20-Jun Lomatium triternatum 30-Apr 23-May 15-Jun

21-Apr 7-Jun 26-Jul

Lomatium grayi 1-Apr 25-Apr 13-May

21-Apr 7-Jun 22-Jun Sphaeralcea parvifolia 26-May 15-Jun 14-Jul

20-May 5-Jul 29-Jul

Sphaeralcea grossulariifolia 26-May 15-Jun 14-Jul

20-May 5-Jul 29-Jul Sphaeralcea coccinea 26-May 15-Jun 14-Jul 20-May 5-Jul 29-Jul

2012

Eriogonum umbellatum 30-May 20-Jun 4-Jul 30-May 11-Jul 24-Jul Penstemon speciosus 2-May 20-May 25-Jun 2-May 13-Jun 13-Jul Lomatium dissectum 9-Apr 16-Apr 16-May 13-Apr 24-May 4-Jun Lomatium triternatum 12-Apr 17-May 6-Jun 13-Apr 24-May 21-Jun Lomatium grayi 15-Mar 25-Apr 16-May 13-Apr 24-May 14-Jun


Table 3. Native wildflower seed harvest and cleaning by species, Malheur Experiment Station, Oregon State University, Ontario, OR. Species Number of

harvests/year Harvest method Pre-

cleaning Threshing method

Cleaning method

Eriogonum umbellatum 1 combinea none dewingerb mechanicalc Penstemon acuminatus 1 combined none combine mechanicalc Penstemon deustus 1 combinea mechanicalc hande mechanicalc Penstemon speciosusf 1 combined none combine mechanicalc Lomatium dissectum 1 hand hand none mechanicalc Lomatium triternatum 1–2 hand hand none mechanicalc Lomatium grayi 1–2 hand hand none mechanicalc Sphaeralcea parvifolia 1–3 hand or combined none combine none Sphaeralcea grossulariifolia 1–3 hand or combined none combine none Sphaeralcea coccinea 1–3 hand or combined none combine none Dalea searlsiae 0 or 2 hand none dewinger mechanicalc Dalea ornate 0 or 2 hand none dewinger mechanicalc a Wintersteiger Nurserymaster small-plot combine with dry bean concave. b Specialized seed threshing machine at USDA Lucky Peak Nursery used in 2006. Thereafter an adjustable hand-driven corn grinder was used to thresh seed. c Clipper seed cleaner. d Wintersteiger Nurserymaster small-plot combine with alfalfa seed concave. For the Sphaeralcea spp., flailing in the fall of 2007 resulted in more compact growth and one combine harvest in 2008, 2009, and 2010. e Hard seed pods were broken by rubbing against a ribbed rubber mat. f Harvested by hand in 2007 and 2009 due to poor seed set.

Results and Discussion Very low precipitation in November and December of 2011 was followed by close to average precipitation from January through June in 2012 resulting in a dry spring and lower soil volumetric water content early in the wildflower growing season. For example, the soil water in the nonirrigated plots of Eriogonum umbellatum in 2012 was much drier compared to wetter years such as 2006 and 2011 (Fig. 3). The soil volumetric water content for all the various species in 2012 started very dry but responded to the irrigation treatments (Figs. 4-8). The accumulated precipitation and growing degree-days (50-86°F) from January through June in 2012 were close to the average (Table 4, Figs. 1 and 2). The relatively dry soil at the beginning of the growing season may have been detrimental to the seed yield of all species in 2012.

Flowering and Seed Set Penstemon acuminatus and P. speciosus had poor seed set in 2007, partly due to a heavy lygus bug infestation that was not adequately controlled by the applied insecticides. In the Treasure Valley, the first hatch of lygus bugs occurs when 250 degree-days (52°F base) are accumulated. Data collected by an AgriMet weather station adjacent to the field indicated that the first lygus bug hatch occurred on May 14, 2006; May 1, 2007; May 18, 2008; May 19, 2009; and May 29, 2010. The average (1995-2010) lygus bug hatch date was May 18. Penstemon acuminatus and P. speciosus


start flowering in early May. The earlier lygus bug hatch in 2007 probably resulted in harmful levels of lygus bugs present during a larger part of the Penstemon spp. flowering period than normal. Poor seed set for P. acuminatus and P. speciosus in 2007 also was related to poor vegetative growth compared to 2006 and 2008. In 2009, all plots of P. acuminatus and P. speciosus again showed poor vegetative growth and seed set. Root rot affected all plots of P. acuminatus in 2009, killing all plants in two of the four plots of the wettest treatment (2 inches per irrigation). Root rot affected the wetter plots of P. speciosus in 2009, but the stand partially recovered due to natural reseeding.

The three Sphaeralcea spp. showed a long flowering period (early May through September) in 2007. Multiple manual harvests were necessary because the seed falls out of the capsules once they are mature. The flailing of the three Sphaeralcea spp. starting in the fall of 2007 was done annually to induce a more concentrated flowering, allowing only one mechanical harvest. Precipitation in June of 2009 (2.27 inches) and 2010 (1.95 inches) was substantially higher than average (0.76 inches). Rust (Puccinia sherardiana) infected all three Sphaeralcea spp. in June of 2009 and 2010, causing substantial leaf loss and reduced vegetative growth.

Seed Yields

Eriogonum umbellatum In 2006, seed yield of Eriogonum umbellatum increased with increasing water application, up to 8 inches, the highest amount tested (Table 5, Fig. 9). In 2007-2009 seed yield showed a quadratic response to irrigation rate (Tables 5 and 6). Seed yields were maximized by 8.1 inches, 7.2 inches, and 6.9 inches of water applied in 2007, 2008, and 2009, respectively. In 2010, there was no significant difference in yield between treatments. In 2011, seed yield was highest with no irrigation. The 2010 and 2011 seasons had unusually cool (Table 4, Fig. 1) and wet weather (Fig. 2). The accumulated precipitation in April through June of 2010 and 2011 was the highest over the years of the trial (Table 4). The relatively high seed yield of E. umbellatum in the nonirrigated treatment in 2010 and 2011 seemed to be related to the high spring precipitation. The negative effect of irrigation on seed yield in 2011 might have been related to the presence of rust. Irrigation could have exacerbated the rust and resulted in lower yields. In 2006, seed yield of Eriogonum umbellatum increased with increasing water application, up to 8 inches, the highest amount tested (Table 5, Fig. 9). Averaged over 7 years, seed yield of E. umbellatum increased with increasing water applied up to 8 inches, the highest amount tested (Fig. 9). The quadratic seed yield responses most years suggests that additional irrigation above 8 inches would not be beneficial.

Penstemon acuminatus There was no significant difference in seed yield between irrigation treatments for P. acuminatus in 2006 (Table 5). Precipitation from March through June was 6.4 inches in 2006. The 64-year-average precipitation from March through June is 3.6 inches. The wet weather in 2006 could have attenuated the effects of the irrigation treatments. In 2007, seed yield showed a quadratic response to irrigation rate (Fig. 10). Seed yields were maximized by 4.0 inches of water applied in 2007. In 2008, seed yield showed a linear response to applied water. In 2009, there was no significant difference in seed yield between treatments (Table 6). However, due to root rot affecting all plots in 2009, the seed yield results were compromised. By 2010, substantial lengths of row contained only


dead plants. Measurements in each plot showed that plant death increased with increasing irrigation rate. The stand loss was 51.3, 63.9, and 88.5 percent for the 0-, 4-, and 8-inch irrigation treatments, respectively. The trial area was disked out in 2010. Following the 2005 planting, seed yields were substantial in 2006 and moderate in 2008. P. acuminatus is a short-lived perennial.

Penstemon speciosus In 2006-2009 seed yield of P. speciosus showed a quadratic response to irrigation rate (Fig. 11, Tables 5 and 6). Seed yields were maximized by 4.3, 4.2, 5.0, and 4.3 inches of water applied in 2006, 2007, 2008, and 2009, respectively. In 2010, 2011, and 2012 there was no difference in seed yield between treatments. Seed yield was low in 2007 due to lygus bug damage, as discussed previously. Seed yield in 2009 was low due to stand loss from root rot. The plant stand recovered somewhat in 2010 and 2011, due in part to natural reseeding, especially in the nonirrigated plots. Averaged over 7 years, seed yield was maximized by 4.5 inches of water applied.

Penstemon deustus There was no significant difference in seed yield between irrigation treatments for P. deustus in 2006 or 2007. Both the replanting of the low stand areas in October 2005 and the replanting of the whole area in October 2006 resulted in very poor emergence and plots with very low and uneven stands. The planting was disked out.

Lomatium triternatum Lomatium triternatum showed a trend for increasing seed yield with increasing irrigation rate in 2007 (Table 5). The highest irrigation rate resulted in significantly higher seed yield than the nonirrigated check treatments. Seed yields of L. triternatum were substantially higher in 2008-2011 (Tables 5 and 6). In 2008–2011 seed yields of L. triternatum showed a quadratic response to irrigation rate (Fig. 12). Seed yields were estimated to be maximized by 8.4, 5.4, 7.8, and 4.1 inches of water applied in 2008, 2009, 2010, and 2011, respectively. In 2012, seed yield increased with increasing water applied up to the highest amount of 8 inches. Averaged over 6 years, seed yield of L. triternatum was estimated to be maximized by 6.2 inches of applied water. Irrigation requirements were lower in 2011.

Lomatium grayi Lomatium grayi showed a trend for increasing seed yield with increasing irrigation rate in 2007 (Table 5). The highest irrigation rate resulted in significantly higher seed yield than the nonirrigated check. Seed yields of L. grayi were substantially higher in 2008 and 2009. In 2008, seed yields of L. grayi showed a quadratic response to irrigation rate (Fig. 13). Seed yields were estimated to be maximized by 6.9 inches of water applied in 2008. In 2009, seed yield showed a linear response to irrigation rate. Seed yield with the 4-inch irrigation rate was significantly higher than in the nonirrigated check, but the 8-inch irrigation rate did not result in a significant increase above the 4-inch rate. In 2010, seed yield was not responsive to irrigation, possibly caused by the unusually wet spring of 2010. A further complicating factor in 2010 that compromised seed yields was rodent damage. Extensive rodent (vole) damage occurred over the 2009-2010 winter. The affected areas were transplanted with 3-year-old L. grayi plants from an adjacent area in the spring of 2010. To


reduce their attractiveness to voles, the plants were mowed after becoming dormant in early fall of 2010. In 2011, seed yield again did not respond to irrigation. The spring of 2011 was unusually cool and wet. In 2012, seed yields of L. grayi showed a quadratic response to irrigation rate, with a maximum seed yield at 5.5 inches of applied water (Fig. 13). Averaged over 6 years, seed yield of L. grayi was estimated to be maximized by 5.2 inches of applied water. More appropriately, irrigation probably should be variable according to precipitation.

Lomatium dissectum Lomatium dissectum had very poor vegetative growth in 2006-2008, and produced only very few flowers in 2008. In 2009, vegetative growth and flowering for L. dissectum were greater. Seed yield of L. dissectum showed a linear response to irrigation rate in 2009 (Fig. 14). Seed yield with the 4-inch irrigation rate was significantly higher than with the nonirrigated check, but the 8-inch irrigation rate did not result in a significant increase above the 4-inch rate. In 2010 and 2011, seed yields of L. dissectum showed a quadratic response to irrigation rate. Seed yields were estimated to be maximized by 5.4 and 5.1 inches of applied water in 2010 and 2011, respectively. In 2012, seed yields of L. dissectum were not responsive to irrigation rate (Fig. 14). Averaged over the 4 years, seed yield showed a quadratic response to irrigation rate and was estimated to be maximized by 5.1 inches of applied water.

All the Lomatium species tested were affected by Alternaria fungus, but the infection was greatest on the L. dissectum selection planted in this trial. This infection might have delayed L. dissectum plant development.

Sphaeralcea spp. In 2007-2011 there were no significant differences in seed yield among irrigation treatments for the three Sphaeralcea spp. (Tables 5 and 6). Stand of the three Sphaeralcea species was poor in 2012 and the planting was eliminated. Conclusions Subsurface drip irrigation systems were tested for native seed production because they have two potential strategic advantages: a) low water use, and b) the buried drip tape provides water to the plants at depth, precluding stimulation of weed seed germination on the soil surface and keeping water away from native plant tissues that are not adapted to a wet environment.

Due to the arid environment, supplemental irrigation may often be required for successful flowering and seed set because soil water reserves may be exhausted before seed formation. The total irrigation requirements for these arid-land species were low and varied by species (Table 7). The Sphaeralcea spp. and Penstemon acuminatus did not respond to irrigation in these trials. Natural rainfall was sufficient to maximize seed production in the absence of weed competition.

Lomatium dissectum required approximately 6 inches of irrigation. Lomatium grayi, L. triternatum, and Eriogonum umbellatum responded quadratically to irrigation with the optimum varying by year. The other species tested had insufficient plant stands to reliably evaluate their response to irrigation.


Management Applications This report describes practices that can be immediately implemented by seed growers. A multi-year summary of research findings is found in Table 7. Table 4. Precipitation and growing degree-days at the Malheur Experiment Station, Ontario, OR.

Precipitation (inches) Growing degree-days (50-86°F) Year Jan-June April-June Jan-June 2006 9 3.1 1120 2007 3.1 1.9 1208 2008 2.9 1.2 936 2009 5.8 3.9 1028 2010 8.3 4.3 779 2011 8.3 3.9 671 2012 5.8 2.3 979

67-year average 5.8 2.7 1028a a25-year average.


Table 5. Native wildflower seed yield response to irrigation rate (inches/season) in 2006, 2007, and 2008. Malheur Experiment Station, Oregon State University, Ontario, OR.

2006 2007 2008

Species 0

inches 4

inches 8

inches LSD

(0.05) 0

inches 4

inches 8

inches LSD

(0.05) 0

inches 4

inches 8

inches LSD

(0.05) ---------------------------------------------------------- lb/acre -------------------------------------------------------- Eriogonum umbellatuma 155.3 214.4 371.6 92.9 79.6 164.8 193.8 79.8 121.3 221.5 245.2 51.7 Penstemon acuminatusa 538.4 611.1 544.0 NS 19.3 50.1 19.1 25.5b 56.2 150.7 187.1 79.0 Penstemon deustusc 1246.4 1200.8 1068.6 NS 120.3 187.7 148.3 NS --- very poor stand --- Penstemon speciosusa 163.5 346.2 213.6 134.3 2.5 9.3 5.3 4.7b 94.0 367.0 276.5 179.6 Lomatium dissectumd ---- no flowering ---- --- no flowering --- --- very little flowering --- Lomatium triternatumd ---- no flowering ---- 2.3 17.5 26.7 16.9b 195.3 1060.9 1386.9 410.0 Lomatium grayid ---- no flowering ---- 36.1 88.3 131.9 77.7b 393.3 1287 1444.9 141.0 Sphaeralcea parvifoliae 1062.6 850.7 957.9 NS 436.2 569.1 544.7 NS Sphaeralcea grossulariifoliae 442.6 324.8 351.9 NS 275.3 183.3 178.7 NS Sphaeralcea coccineae 279.8 262.1 310.3 NS 298.7 304.1 205.2 NS

a planted March, 2005, areas of low stand replanted by hand in October 2005. b LSD (0.10). c planted March, 2005, areas of low stand replanted by hand in October 2005 and whole area replanted in October 2006. Yields in 2006 are based

on small areas with adequate stand. Yields in 2007 are based on whole area of very poor and uneven stand. d planted March, 2005, whole area replanted in October 2005. e planted spring 2006, whole area replanted in November 2006.

Table 6. Native wildflower seed yield response to irrigation rate (inches/season) in 2009- 2012, and 2- to 7-year averages. Malheur Experiment Station, Oregon State University, Ontario, OR.

2009 2010 2011

Species 0

inches 4

inches 8

inches LSD

(0.05) 0

inches 4

inches 8

inches LSD

(0.05) 0

inches 4

inches 8

inches LSD

(0.05)

----------------------------------------------------------------------- lb/acre ------------------------------------------------------------------

Eriogonum umbellatuma 132.3 223 240.1 67.4

252.9 260.3 208.8 NS

248.7 136.9 121.0 90.9 Penstemon acuminatusa 20.7 12.5 11.6 NS

-- Stand disked out --

Penstemon speciosusa 6.8 16.1 9.0 6.0b

147.2 74.3 69.7 NS

371.1 328.2 348.6 NS Lomatium dissectumd 50.6 320.5 327.8 196.4b

265.8 543.8 499.6 199.6

567.5 1342.8 1113.8 180.9

Lomatium triternatumd 181.6 780.1 676.1 177

1637.2 2829.6 3194.6 309.4

1982.9 2624.5 2028.1 502.3b Lomatium grayid 359.9 579.8 686.5 208.4

1035.7 1143.5 704.8 NS

570.3 572.7 347.6 NS

Sphaeralcea parvifoliae 285.9 406.1 433.3 NS

245.3 327.3 257.3 NS

81.6 142.5 141.2 NS Sphaeralcea grossulariifoliae 270.7 298.9 327.0 NS

310.5 351 346.6 NS

224.0 261.9 148.1 NS

Sphaeralcea coccineae 332.2 172.1 263.3 NS 385.7 282.6 372.5 NS 89.6 199.6 60.5 NS

2012

4- to 7-year averages

0 inches

4 inches

8 inches

LSD (0.05)

0 inches

4 inches

8 inches

LSD (0.05) Species

Eriogonum umbellatuma 61.2 153.2 185.4 84.4

154.5 194.2 217.4 30.8 Penstemon acuminatusa

163.8 204.8 189.9 NS

Penstemon speciosusa 103.8 141.1 99.1 NS

127.8 174.8 145.8 30.5b Lomatium dissectumd 388.1 460.3 444.4 NS

318.0 719.1 596.4 179.4

Lomatium triternatumd 238.7 603.0 733.2 323.9

706.3 1319.3 1341.0 192.4 Lomatium grayid 231.9 404.4 377.3 107.4

437.9 679.3 615.5 185.5

Sphaeralcea parvifoliae

449.9 495.9 495.8 NS Sphaeralcea grossulariifoliae

339.5 323.4 309.4 NS

Sphaeralcea coccineae

320.5 275.8 284.2 NS a planted March, 2005, areas of low stand replanted by hand in October 2005.

b LSD (0.10). c planted March, 2005, areas of low stand replanted by hand in October 2005 and whole area replanted in October 2006. Yields in 2006 were based

on small areas with adequate stand. Yields in 2007 were based on whole area of very poor and uneven stand. d planted March, 2005, whole area replanted in October 2005. e planted spring 2006, whole area replanted in November 2006.

Table 7. Amount of irrigation water for maximum native wildflower seed yield, years to seed set, and life span. A summary of multi-year research findings, Malheur Experiment Station, Oregon State University, Ontario, OR.

Species Optimum amount of irrigation Years to first seed set Life span

inches/season from fall planting years

Eriogonum umbellatum 0 in wet years, 7 to 8 in dry years 1 7+ Penstemon acuminatus no response 1 3 Penstemon speciosus 0 in wet years, 4 in dry years 1 3 Lomatium dissectum 5 4 7+ Lomatium triternatum 4 to 8 depending on precipitation 2 7+ Lomatium grayi 0 in wet years, 5 in dry years 2 7+ Sphaeralcea parvifolia no response 1 5 Sphaeralcea grossulariifolia no response 1 5 Sphaeralcea coccinea no response 1 5


Figure 1. Cumulative annual and 22-year average growing degree-days at the Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 2. Cumulative annual and 68-year average precipitation from January through July at the Malheur Experiment Station, Oregon State University, Ontario, OR.


Figure 3. Soil volumetric water content in nonirrigated Eriogonum umbellatum over 7 years. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 4. Soil volumetric water content for Eriogonum umbellatum over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on May 30 and ended on July 11. Arrows denote irrigations. E. umbellatum was harvested on July 24 (day 205). Malheur Experiment Station, Oregon State University, Ontario, OR.


Figure 5. Soil volumetric water content for Penstemon speciosus over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on May 2 and ended on June 13. Arrows denote irrigations. P. speciosus was harvested on July 13 (day 194). Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 6. Soil volumetric water content for Lomatium triternatum over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 13 and ended on May 24. Arrows denote irrigations. L. triternatum was harvested on June 21 (day 172). Malheur Experiment Station, Oregon State University, Ontario, OR.


Figure 7. Soil volumetric water content for Lomatium grayi over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 13 and ended on May 24. Arrows denote irrigations. L. grayi was harvested on June 14 (day 165). Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 8. Soil volumetric water content for Lomatium dissectum over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 13 and ended on May 24. Arrows denote irrigations. L. dissectum was harvested on June 4 (day 155). Malheur Experiment Station, Oregon State University, Ontario, OR.


Figure 9. Average annual Eriogonum umbellatum seed yield response to irrigation water applied in 7 years and averaged over 7 years, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Regression equations: 2006, Y = 137.9 + 27.8X, R2 = 0.68, P = 0.01; 2007, Y = 79.6 + 28.3X – 1.75X2, R2 = 0.69, P = 0.05; 2008, Y = 121.3 + 34.6X – 2.4X2, R2 = 0.73, P = 0.01; 2009, Y = 132.3 + 31.9X – 2.3X2, R2 = 0.60, P = 0.05; 2010, Y = 252.9 + 9.21X – 1.8X2, R2 = 0.08, P = NS; 2011, Y = 232.7 – 16.0X, R2 = 0.58, P = 0.01; 2012, 71.2 + 15.5X, R2 = 0.61, P = 0.01; 7-year average, Y = 157.2 + 7.9X, R2 = 0.68, P = 0.01.

Figure 10. Annual Penstemon acuminatus seed yield response to irrigation water from 2006 to 2008. Malheur Experiment Station, Oregon State University, Ontario, OR. Regression equations: 2006, Y = 538.4 + 35.6X – 4.4X2, R2 = 0.03, P = NS; 2007, Y = 19.3 + 15.4X – 1.9X2, R2 = 0.44, P = 0.10; 2008, Y = 84.5 + 13.6X, R2 = 0.49, P = 0.05.


Figure 11. Annual and 7-year (2006-2012) average Penstemon speciosus seed yield response to irrigation water, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Regression equations: 2006, Y = 163.5 + 85.1X – 9.9X2, R2 = 0.66, P = 0.05; 2007, Y = 2.5 + 3.2X – 0.38X2, R2 = 0.48, P = 0.10; 2008, Y = 94.1 + 113.7X – 11.4X2, R2 = 0.56, P = 0.05; 2009, Y = 6.8 + 4.4X – 0.52X2, R2 = 0.54, P = 0.05; 2010, Y = 147.2 + 29.81X – 2.1X2, R2 = 0.35, P = NS; 2011, Y = 360.6 – 2.82X, R2 = 0.01, P = NS; 2012, 103.8 + 19.3X – 2.5X2, R2 = 0.30, P = NS; 7-year average, Y = 127.8 + 21.2X – 2.4X2; R2 = 0.37, P = NS.

Figure 12. Annual and 6-year (2007-2012) average Lomatium triternatum seed yield response to irrigation water applied, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Regression equations: 2007, Y = 3.26 + 3.06X, R2 = 0.52, P = 0.01; 2008, Y = 195.3 + 283.9X – 16.9X2, R2 = 0.77, P = 0.01; 2009, Y = 181.6 + 237.4X – 22.0X2, R2 = 0.83, P = 0.001; 2010, Y = 1637.2 + 401.5X – 25.9X2, R2 = 0.83, P = 0.001; 2011, Y = 1982.932 + 315.1X – 38.7X2, R2 = 0.45, P = 0.10; 2012, 277.8 + 61.8X, R2 = 0.49, P = 0.05; 6-year average, Y = 706.3 + 227.1X – 18.5X2, R2 = 0.80, P = 0.001.


Figure 13. Annual and 6-year (2007-2012) average Lomatium grayi seed yield response to irrigation water applied, Malheur Experiment Station, Oregon State University, Ontario OR, 2012. Regression equations: 2007, Y = 37.5 + 12.0X, R2 = 0.26, P = 0.10; 2008, Y = 393.3 + 315.4X – 23.0X2, R2 = 0.93, P = 0.001; 2009, Y = 378.7 + 40.8X, R2 = 0.38, P = 0.05; 2010, Y = 1035.7 + 95.3X – 17.1X2, R2 = 0.22, P = NS; 2011, Y = 608.2 – 27.8X, R2 = 0.07, P = NS; 2012, Y = 231.9 + 68.1X – 6.2X2, R2 = 0.66, P = 0.01; 6-year average, Y = 437.9 + 98.5X – 9.5X2, R2 = 0.49, P = 0.05.

Figure 14. Annual and 4-year (2009-2012) average Lomatium dissectum seed yield response to irrigation water, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012. Regression equations: 2009, Y = 86.4 + 34.6X, R2 = 0.31, P = 0.10; 2010, Y = 265.8 + 109.8X – 10.1X2, R2 = 0.68, P = 0.01; 2011, Y = 567.5 + 319.3X – 31.4X2, R2 = 0.86, P = 0.001; 2012, Y = 402.7 + 7.0X, R2 = 0.04, P = NS; 4-year average, Y = 318.0 + 165.7X – 16.4X2, R2 = 0.79, P = 0.001.


PRELIMINARY ESTIMATES OF THE IRRIGATION REQUIREMENTS FOR NOVEL NATIVE WILDFLOWER SEED PRODUCTION Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Nancy Shaw, U.S. Forest Service, Rocky Mountain Research Station, Boise, ID

Ram S. Sampangi, University of Idaho, Parma, ID Introduction Native wildflower seed is needed to restore rangelands of the Intermountain West. Commercial seed production is necessary to provide the quantity of seed needed for restoration efforts. A major limitation to economically viable commercial production of native wildflower (forb) seed is stable and consistent seed productivity over years.

In natural rangelands, the natural variations in spring rainfall and soil moisture result in highly unpredictable water stress at flowering, seed set, and seed development, which for other seed crops is known to compromise seed yield and quality.

Native wildflower plants are not well adapted to croplands. Native plants are often not competitive with crop weeds in cultivated fields. Poor competitiveness with weeds could also limit wildflower seed production. Both sprinkler and furrow irrigation could provide supplemental water for seed production, but these irrigation systems risk further encouraging weeds. Also, sprinkler and furrow irrigation can lead to the loss of plant stand and seed production due to fungal pathogens. By burying drip tapes at 12-inch depth and avoiding wetting the soil surface, we hoped to assure flowering and seed set without undue encouragement of weeds or opportunistic diseases. The trials reported here tested the effects of three low rates of irrigation on the seed yield of 11 native wildflower species (Table 1) planted in 2009.

Materials and Methods Plant Establishment

In November 2009, drip tape (T-Tape TSX 515-16-340) was buried at 12-inch depth between two 30-inch rows of a Nyssa silt loam with a pH of 8.3 and 1.1 percent organic matter. The drip tape was buried in alternating inter-row spaces (5 ft apart). The flow rate for the drip tape was 0.34 gal/min/100 ft at 8 psi with emitters spaced 16 inches apart, resulting in a water application rate of 0.066 inch/hour.

Preliminary Estimates of the Irrigation Requirements for Novel Native Wildflower Seed Production 160

On November 25, 2009 seed of 9 perennial species (Table 1) was planted in 30-inch rows using a custom-made plot grain drill with disk openers. All seed was planted on the soil surface at 20-30 seeds/ft of row. After planting, sawdust was applied in a narrow band over the seed row at 0.26 oz/ft of row (558 lb/acre). Following planting and sawdust application, the beds were covered with row cover. The row cover (N-sulate, DeWitt Co., Inc., Sikeston, MO) covered four rows (two beds) and was applied with a mechanical plastic mulch layer. The field was irrigated for 24 hours on December 2, 2009 due to very dry soil conditions.


After the newly planted wildflowers had emerged, the row cover was removed in April. The irrigation treatments were not applied to these wildflowers in 2010. Stands of Penstemon cyaneus, P. pachyphyllus, and Eriogonum heracleoides were not adequate for an irrigation trial. Gaps in the rows were replanted by hand on November 5. The replanted seed was covered with a thin layer of a mixture of 50 percent sawdust and 50 percent hydro seeding mulch (Hydrostraw LLC, Manteno, IL) by volume. The mulch mixture was sprayed with water using a backpack sprayer.

On November 18, 2010, seed of Cleome serrulata was planted as previously described.


Seed from the middle 2 rows in each plot of Penstemon deustus and Eriogonum heracleoides was harvested with a small plot combine. Seed from the middle 2 rows in each plot of the other species was harvested manually. On November 11, 2011, seed of Cleome serrulata was planted as previously described. On December 5, 2011, seed of C. lutea was planted as previously described.


Many areas of the wildflower seed production were suffering from severe iron deficiency early in the spring of 2012. On April 13, 2012, 50 lb nitrogen/acre, 10 lb phosphorus/acre, and 5 lb iron (Fe)/acre was applied to all plots of Lomatium nudicaule, Cymopterus bipinnatus, Penstemon deustus, P. cyaneus, and P. pachyphyllus as liquid fertilizer injected through the drip tape. On April 23, 2012, 5 lb Fe/acre was applied to all plots of P. deustus, P. cyaneus, P. pachyphyllus, Eriogonum heracleoides, Dalea searlsiae, D. ornata, and Astragalus filipes as liquid fertilizer injected through the drip tape.

Flea beetles were observed feeding on leaves of Cleome serrulata and C. lutea in April. On April 29, all plots of C. serrulata and C. lutea were sprayed with Capture® at 5 oz/acre to control flea beetles. On June 11, C. serrulata was again sprayed with Capture at 5 oz/acre to control a reinfestation of flea beetles.

A substantial amount of plant death occurred in the Penstemon deustus plots during the winter and spring of 2011/2012. For P. deustus, only the undamaged parts in each plot were harvested. Seed of all species was harvested and cleaned manually.


Table 1. Wildflower species planted in the fall of 2009 at the Malheur Experiment Station, Oregon State University, Ontario, OR. All species are perennial except Cleome serrulata and Cleome lutea.

Species Common names Penstemon deustus Scabland penstemon, hotrock penstemon Penstemon cyaneus Blue penstemon Penstemon pachyphyllus Thickleaf beardtongue Eriogonum heracleoides Parsnip flower buckwheat Dalea searlsiae Searls’ prairie clover Dalea ornata Western prairie clover, Blue Mountain prairie clover Astragalus filipes Basalt milkvetch Cleome serrulata Cleome lutea Lomatium nudicaule Cymopterus bipinnatus

Rocky Mountain beeplant Yellow beeplant Barestem biscuitroot, Barestem lomatium Hayden's cymopterus

Irrigation for Seed Production In April, 2011, each plot strip of each wildflower species was divided into plots 30 ft long. Each plot contained four rows of each species. The experimental design for each species was a randomized complete block with four replicates. The three irrigation treatments were a nonirrigated check, 1 inch per irrigation, and 2 inches per irrigation. Each treatment received 4 irrigations that were applied approximately every 2 weeks starting with flowering of the wildflowers. The amount of water applied to each treatment was calculated by the length of time necessary to deliver 1 or 2 inches through the drip system. Irrigations were regulated with a controller and solenoid valves. After each irrigation, the amount of water applied was read on a water meter and recorded to ensure correct water applications.

The drip-irrigation system was designed to allow separate irrigation of the species due to different timings of flowering and seed formation. The three Penstemon spp. were irrigated together and the two Dalea spp. were irrigated together. Eriogonum heracleoides and Astragalus filipes were irrigated individually. Flowering, irrigation, and harvest dates were recorded (Table 2). Lomatium nudicaule flowered in 2012; irrigation treatments were applied and seed was harvested. Cymopterus bipinnatus has not flowered as of 2012, but differential irrigation treatments were applied to Cymopterus bipinnatus in 2012.

Soil volumetric water content was measured by neutron probe. The neutron probe was calibrated by taking soil samples and probe readings at 8-, 20-, and 32-inch depths during installation of the access tubes. The soil water content was determined volumetrically from the soil samples and regressed against the neutron probe readings for each soil depth. Regression equations were then used to transform the neutron probe readings during the season into volumetric soil water content.


Table 2. Native wildflower flowering, irrigation, and seed harvest dates by species. Malheur Experiment Station, Oregon State University, Ontario, OR. Flowering Irrigation Species start peak end start end Harvest

2011

Penstemon cyaneus 23-May 15-Jun 8-Jul

13-May 23-Jun 18-Jul Penstemon pachyphyllus 10-May 30-May 20-Jun

13-May 23-Jun 15-Jul

Penstemon deustus 23-May 20-Jun 14-Jul

13-May 23-Jun 16-Aug Eriogonum heracleoides 26-May 10-Jun 8-Jul

27-May 6-Jul 1-Aug

Dalea searlsiae 8-Jun 20-Jun 20-Jul

27-May 6-Jul 21-Jul Dalea ornata 8-Jun 20-Jun 20-Jul

27-May 6-Jul 22-Jul

Astragalus filipes 20-May 26-May 30-Jun

13-May 23-Jun 18-Jul Cleome serrulata 25-Jun 30-Jul 15-Aug

21-Jun 2-Aug 26-Sep

Lomatium nudicaule

No flowering Cymopterus bipinnatus

No flowering

2012 Penstemon cyaneus 16-May 30-May 10-Jun

27-Apr 7-Jun 27-Jun

Penstemon pachyphyllus 23-Apr 2-May 10-Jun

27-Apr 7-Jun 26-Jun Penstemon deustus 16-May 30-May 4-Jul

27-Apr 7-Jun 7-Aug

Eriogonum heracleoides 23-May 30-May 25-Jun

11-May 21-Jun 16-Jul Dalea searlsiae 23-May 10-Jun 30-Jun

11-May 21-Jun 10-Jul

Dalea ornata 23-May 10-Jun 30-Jun

11-May 21-Jun 11-Jul Astragalus filipes 28-Apr 23-May 19-Jun

11-May 21-Jun 5-Jul

Cleome serrulata 12-Jun 30-Jun 30-Jul

13-Jun 25-Jul 24-Jul to 30-Aug Cleome lutea 16-May 15-Jun 30-Jul

2-May 13-Jun 12-Jul to 30-Aug

Lomatium nudicaule 12-Apr 1-May 30-May

18-Apr 30-May 22-Jun Cymopterus bipinnatus No flowering

Results and Discussion

Seed Yields in 2011

Seed yield of all species, except Cleome serrulata, either had a negative response to irrigation (Dalea searlsiae and Penstemon deustus) or did not respond to irrigation (Dalea ornata and Astragalus filipes) (Table 3, Figs. 3-5). Seed yield of Cleome serrulata was highest with the highest amount of water applied (8 inches). The higher than average winter moisture and precipitation in March and May reduced the effect of the irrigation treatments for the species that flowered in May and June (Fig. 1). Cleome serrulata started flowering in late June and peaked in August, when precipitation was lower. Seed yields of Penstemon cyaneus and P. pachyphyllus did not respond to irrigation, but the results might have been compromised by the poor stand in many plots.

Seed Yields in 2012


Precipitation was lower in 2012 than in 2011(Fig. 1) and the accumulated growing degree-days was higher in 2012 than in 2011 (Fig. 2). Very low precipitation in November and December of 2011 was followed by close to average precipitation from January through June in 2012 resulting in a dry spring and in lower soil volumetric water content early in the wildflower growing season. The soil volumetric water content was very low for Penstemon deustus (Fig. 11) at the start of the growing season. The soil volumetric water content responded to the irrigation treatments on each species (Figs. 8-14).

Seed yield of Penstemon cyaneus was highest with the highest amount of water applied. Seed yield of Dalea searlsiae increased with increasing irrigation rate up to 6.6 inches of water applied (Table 3, Fig. 6). Seed yield of D. ornata increased with increasing irrigation rate up to 7.7 inches of water applied (Table 3, Fig. 7). None of the other species tested had statistically significant seed yield responses to irrigation in 2012.


Figure 1. Cumulative annual and 66-year-average precipitation from January through July at the Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 2. Cumulative growing degree-days (50-86°F ) for selected years and 20-year average at the Malheur Experiment Station, Oregon State University, Ontario, OR.


Table 3. Native wildflower seed yield response to irrigation rate (inches/season). Malheur Experiment Station, Oregon State University, Ontario, OR.

2011

2012

Average

0

inches 4

inches 8

inches LSD

(0.05) 0

inches 4

inches 8

inches LSD

(0.05) 0

inches 4

inches 8

inches LSD

(0.05) Species

--------- lb/acre ---------

--------- lb/acre ---------

--------- lb/acre ---------

Penstemon cyaneus 857.2 821.4 909.4 NS

343.3 474.6 581.2 202.6b

600.3 648.0 745.3 NS Penstemon pachyphyllus 569.9 337.6 482.2 NS

280.5 215.0 253.7 NS

425.2 276.3 368.0 NS

Penstemon deustus 637.6 477.8 452.6 NS

308.7 291.8 299.7 NS

512.7 403.1 374.2 NS Eriogonum heracleoides 55.2 71.6 49.0 NS

252.3 316.8 266.4 NS

153.8 194.2 157.7 NS

Dalea searlsiae 262.7 231.2 196.3 50.1

175.5 288.8 303.0 93.6

219.1 260.0 249.6 NS Dalea ornata 451.9 410.8 351.7 NS

145.1 365.1 431.4 189.3

298.5 387.9 391.6 NS

Astragalus filipes 87.0 98.4 74.0 NS

22.7 12.6 16.1 NS

87.0 98.4 74.0 NS Lomatium nudicaule

53.8 123.8 61.1 NS

Cleome serrulata 446.5 499.3 593.6 100.9b

184.3 162.9 194.7 NS

154.5 194.2 217.4 NS Cleome lutea 111.7 83.7 111.4 NS bLSD (0.10)

Figure 3. Penstemon deustus seed yield response to irrigation water applied in 2011. Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 4. Cleome serrulata seed yield response to irrigation water applied in 2011. Malheur Experiment Station, Oregon State University, Ontario, OR.


Figure 5. Dalea searlsiae seed yield response to irrigation water applied in 2011. Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 6. Dalea searlsiae seed yield response to irrigation water applied in 2012. Malheur Experiment Station, Oregon State University, Ontario, OR.


Figure 7. Dalea ornata seed yield response to irrigation water applied in 2012. Malheur Experiment Station, Oregon State University, Ontario, OR.

Figure 8. Soil volumetric water content for Eriogonum heracleoides over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on May 11 and ended on June 21. Arrows denote irrigations. E. heracleoides was harvested on July 16 (day 197). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 9. Soil volumetric water content for Penstemon cyaneus over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 27 and ended on June 7. Arrows denote irrigations. P. cyaneus was harvested on June 27 (day 178). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 10. Soil volumetric water content for Penstemon pachyphyllus over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 27 and ended on June 7. Arrows denote irrigations. P. pachyphyllus was harvested on June 26 (day 177). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 11. Soil volumetric water content for Penstemon deustus over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 27 and ended on June 7. Arrows denote irrigations. P. deustus was harvested on August 7 (day 219). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 12. Soil volumetric water content for Dalea searlsiae over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on May 11 and ended on June 21. Arrows denote irrigations. D. searlsiae was harvested on July 10 (day 191). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


Figure 13. Soil volumetric water content for Dalea ornata over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on May 11 and ended on June 21. Arrows denote irrigations. D. ornata was harvested on July 11 (day 192). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.

Figure 14. Soil volumetric water content for Astragalus filipes over time in 2012. Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on May 11 and ended on June 21. Arrows denote irrigations. A. filipes was harvested on July 5 (day 186). Malheur Experiment Station, Oregon State University, Ontario, OR, 2012.


TOLERANCE OF SULPHUR-FLOWER BUCKWHEAT (ERIOGONUM UMBELLATUM) TO RATES AND MIXTURES OF POSTEMERGENCE HERBICIDES, 2008–2012 Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders, Malheur Experiment Station, Oregon State University, Ontario, OR Nancy Shaw, U.S. Forest Service, Rocky Mountain Research Station, Boise, ID Introduction Native forb seed is needed to restore rangelands of the Intermountain West. Commercial seed production is necessary to provide the quantity of seed needed for restoration efforts. A major limitation to economically viable commercial production of native forb seed is weed competition. Weeds are adapted to growing in disturbed soil, and native forbs are not competitive with these weeds. The use of preemergence and postemergence herbicides for forb weed control is important, because forbs are fall planted. Fall planting results in nearly simultaneous forb and weed emergence early in the spring, complicating weed control. There is considerable knowledge about the relative efficacy of different herbicides to control target weeds, but few trials have tested the tolerance of native forbs to commercial herbicides. This trial evaluated the tolerance of sulphur-flower buckwheat (Eriogonum umbellatum) to the herbicides Select® (clethodim), Prowl® (pendimethalin), and Outlook® (dimethenamid-p). Prowl and Outlook are broad-spectrum, soil-active herbicides that prevent weed emergence during the growing season. Select is a foliar-contact grass herbicide.

This work sought to discover products that could eventually be registered for use for native forb seed production. The information in this report is for the purpose of informing cooperators and colleagues in other agencies, universities, and industry of the research results. Reference to products and companies in this publication is for the specific information only and does not endorse or recommend that product or company to the exclusion of others that may be suitable. Nor should any information and interpretation thereof be considered as recommendations for the application of any of these herbicides. Pesticide labels should always be consulted before any pesticide use. Considerable efforts may be required to register these herbicides for use in native forb seed production. Materials and Methods The trial was conducted on a field of Nyssa silt loam with a pH of 8.3 and 1.1 percent organic matter. Before planting, drip tape (T-Tape TSX 515-16-340) was buried at 12-inch depth midway between two 30-inch rows. The drip tapes were buried 5 ft apart in alternating inter-row

Tolerance of Sulphur-flower Buckwheat (Eriogonum umbellatum) to Rates and Mixtures of Postemergence Herbicides, 2008–2012 173

spaces (5 ft apart). The flow rate for the drip tape was 0.34 gal/min/100 ft at 8 psi with emitters spaced 16 inches apart, resulting in a water application rate of 0.066 inch/hour. In the fall of 2006, sulphur-flower buckwheat was planted in an area 10 ft wide and 220 ft long. The seeds were planted at 0.25-inch depth in 4 rows 30 inches apart. The field previously had been disked, ground hogged, and marked in rows 30 inches apart. A total of 4 drip irrigations applying 1 inch of water each were applied at 2-week intervals in 2007–2010. Drip irrigations were started when the flowering began. The trial was not irrigated in 2011.

On March 12, 2008, March 20, 2009, April 7, 2010, April 1, 2011, and April 10, 2012 13 herbicide treatments (Table 1) were applied to plots 4 rows wide and 5 ft long. The treatments consisted of different rates and combinations of the soil-active herbicides Prowl and Outlook. The treatments were arranged in a randomized complete block design with four replications. Treatments were applied at 30 psi, 2.63 mph, and 20 gal/acre using 8002 nozzles with 6 nozzles spaced 20 inches apart.

Seed was harvested at maturity from the middle two rows in each plot each year.

General Considerations The focus of the evaluations was forb tolerance to the herbicides, not weed control, so weeds were removed as needed.

Treatment differences were compared using ANOVA and protected least significant differences at the 95 percent confidence LSD (0.05) using NCSS Number Cruncher software (NCSS, Kaysville, UT). Results and Discussion All observations made on the herbicides tested are strictly preliminary observations. Herbicides that damaged forbs as reported here might be helpful if used at a lower rate or in a different environment. The herbicides were relatively safe for sulphur-flower buckwheat in this trial but they might be harmful if used at higher rates or in a different environment. Nothing in this report should be construed as a recommendation.

Symptoms of herbicide injury were not observed in any of the plants in any year. Foliar injury would not be expected since all herbicides tested (except Select) were soil active and were applied early. There were no significant differences in seed yield between the herbicide treatments and the untreated check in 2008 and 2009 (Table 1). In 2010, Prowl at 1.43 lb ai/acre produced a higher seed yield than the check. In 2011, Prowl at 1.43 lb ai/acre and the mixture of Prowl at 1.19 lb ai/acre with Outlook at 0.84 lb ai/acre had a higher yield than the check. These herbicide treatments could have provided better weed control than the check, had the check not been kept weed free by hand weeding. In 2012, there were no significant differences in seed yield between the herbicide treatments and the untreated check.


Summary Sulphur-flower buckwheat was tolerant to Prowl and Outlook applied as postemergence treatments at the rate and timing and on the soils used in these trials. The use of these three herbicides may provide the basis for an effective weed control program for seed production of sulphur-flower buckwheat. Further tests are warranted to describe the range of safety for these herbicides and whether or not they have any undesirable interactions. Seed yields in 2012 were low. The soil water started very low in April, which may have had a detrimental effect on the seed yield of all of the treatments. Table 1. Seed yield of sulphur-flower buckwheat (Eriogonum umbellatum) in response to repeated postemergence herbicides applied on March 12, 2008, March 20, 2009, April 7, 2010, April 1, 2011, and April 10, 2012. Malheur Experiment Station, Oregon State University, Ontario, OR. Prowl and Outlook are soil-active herbicides and Select is a foliar-contact grass herbicide.

Treatment Rate 2008 2009 2010 2011 2012

(lbs ai/acre) --------------------------- lb/acre ------------------------

Weed free, untreated control

276.5 430.0 622.6 346.2 89.5

Select 2.0 ECa 0.094 149.1 475.2 618.1 285.3 141.2 Prowl 0.95 387.2 440.8 549.7 406.9 120.9 Prowl 1.19 533.1 596.6 736.5 356.0 105.1 Prowl 1.43 250.6 596.4 988.8 502.3 105.9 Outlook 0.84 319.8 474.5 725.2 440.1 89.7 Outlook 0.98 143.5 501.4 627.4 251.7 137.1 Prowl + Outlook 0.95 + 0.66 300.9 555.5 795.5 357.0 154.9 Prowl + Outlook 0.95 + 0.84 440.0 763.8 861.3 464.0 61.2 Prowl + Outlook 0.95 + 0.98 330.9 569.1 614.8 436.0 59.8 Prowl + Outlook 1.19 + 0.66 244.0 699.8 618.5 433.7 129.7 Prowl + Outlook 1.19 + 0.84 336.7 556.0 592.2 513.6 57.9 Prowl + Outlook 1.19 + 0.98 285.6 506.2 684.3 367.0 126.3 Average 307.5 551.2 695.0 396.9 106.1 LSD (0.05) NS NS 241.7 149.5 NS

aapplied with Herbimax adjuvant at 1 percent v/v.


BIOLOGY, DEVELOPMENT, AND TUBER PRODUCTION OF TWO YELLOW NUTSEDGE (Cyperus esculentus) VARIETIES IN THE TREASURE VALLEY Joel Felix and Joey Ishida, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012

Introduction Yellow nutsedge (YNS) has become a problem weed in the Treasure Valley of eastern Oregon and southwestern Idaho. The negative consequences of YNS on onion production are extreme. Studies at the Malheur Experiment Station indicated that onion yield losses are between 23 and 63 percent in heavily infected fields. The state of YNS in the Treasure Valley is evolving. In 2011 we confirmed the coexistence of Cyperus esculentus var. leptostachyus (referred to as ‘true type’) and Cyperus esculentus var. heermannii (referred to as ‘new type’). The main visual differentiating characteristic between the varieties is the inflorescence (flower arrangement) (Fig. 1). The inflorescence of the true type has small spikelet angle, very high spikelet density, and has secondary leaf-like structures (bracts) on the spikes. The plant form for the new type sometimes varies to include multiple stems clustered at the base of the plant (see Fig. 1). Variety heermannii is considered relatively rare in the United States, and until now, it had been reported to be present only in California, Utah, and Florida (Flora of North America). A field survey was conducted during September 2011 to document the distribution of the new type YNS variety. The survey covered fields on the eastern and western sides of highway 201 from near Adrian, Oregon to the area known as the ‘Oregon slope’ (west of Weiser, ID). The new type variety was found in fields planted to onion, sugar beet, and pinto beans. We are not aware of any published information in the literature addressing the growth biology, requirements for tuber germination, and tuber production output for var. heermannii under field conditions.

Materials and Methods Three field studies were established during fall 2011 at the Malheur Experiment Station, Ontario, Oregon to compare the emergence, growth and development, and tuber production of the two YNS varieties (C. esculentus var. leptostachyus and heermannii) in the Treasure Valley.

Study 1 The study determined the timing of tuber emergence for the two YNS varieties in response to depth of tuber placement. One hundred tubers were uniformly distributed in 1.6 by 1.6-ft metal enclosures buried to 24-inch depth. Tubers of each variety were planted at 2- or 4-inch depth on November 17, 2011. Treatments were arranged in randomized complete block design with four

Biology, Development, and Tuber Production of Two Yellow Nutsedge (Cyperues esculentus) Varieties in The Treasure Valley 176

replications. Cumulative YNS emergence was monitored during the spring of 2012. Emerged plants were counted daily and removed.

Study 2 The two YNS varieties were compared for their date of emergence and tuber production. The study had a split-plot design with varieties forming the main plots, while tuber depth of placement was randomly assigned to each variety as subplot. Polyvinyl chloride (PVC) pipes were buried to a 20-inch depth and filled with soil. A single tuber was planted in each PVC pipe at 2-, 6-, 10-, 14-, or 18-inch depth on November 18, 2011. The PVC pipes were retrieved in October 2012 and the soil was washed to quantify YNS tubers.

Study 3 Emergence, growth and development, and tuber production for the two YNS varieties were evaluated using a split-plot design with four replications. The two YNS varieties were the main plots, while time of harvesting was the subplot. Eighty pots (each measuring 10 inches in diameter by 12 inches deep) were filled with soil and 1 tuber/pot was planted at 2-inch depth on November 17, 2011. The pots were buried with the top of the pot at ground level. Four pots were harvested biweekly starting June 15, 2012 and processed to determine plant height, number of stems, aboveground and belowground biomass, and the number of tubers.

All Studies Tubers used in these studies were collected locally. The YNS tubers were planted into soil that was from a non-YNS infested field. Emergence was monitored starting March 2012 and irrigation commenced on April 6, 2012 for the three studies. Each pot or PVC pipe was irrigated with one emitter rated at 1 gal/hour flow rate. The metal enclosures had two emitters each. Weekly irrigation for YNS in the pots and PVC pipes lasted 8 hours. The irrigation duration was 12 hours for yellow nutsedge in the metal enclosures. A soil agitation and washing method was used to recover tubers (Felix and Ishida 2009). The data were subjected to analysis of variance, and quadratic regression models in SigmaPlot® were used to construct the graphs. The regressions presented here are on treatment averages and future regression analyses will be done on all the data.

Results and Discussion Study 1 The true type YNS variety emerged more rapidly than the new type (Fig. 1). Emergence for the true type tubers planted at 2- and 4-inch depth began on April 20 at 19 percent and 13 percent, respectively. The respective cumulative germination for true type tubers peaked at 85 percent and 84 percent on May 9, 2012 as a function of planting depth. Planting depth also affected the emergence of the new type tubers. When planted at the 2-inch depth, only about 1 percent of the new type tubers had emerged on April 20. Emergence for the new type tubers planted at the 4-inch depth was noted on April 24 at only 0.3 percent. Emergence for the new type tubers planted at the 2- and 4-inch depth peaked on May 9 at 50 and 77 percent, respectively. Cumulative emergence for both varieties followed a quadratic relationship over time. Emergence counts were


stopped on May 9 to avoid inclusion of secondary sprouts from the same tubers. These results suggested relatively late emergence for the new type variety and possible differential effects of depth of tuber placement between the varieties. The management implications are that most new type tubers will emerge after soil-applied herbicides have been degraded. This could result in extensive tuber population buildup in infested fields.

Study 2 Total tuber production varied between the two varieties (Fig. 3). Also, tuber placement depth affected the date of emergence for the two varieties. Emergence for the true type tubers planted at 2-inch depth was observed on April 25 compared to May 2 for the new type variety at the same depth. Emergence for true type and new type tubers planted at the 6-inch depth was on May 4 and May 6, respectively. Tubers planted at the 10- to 18-inch depth started to emerge in June for both varieties. The true type variety produced fewer tubers, ranging from 358 to 921 tubers/1,558 cubic inches of soil compared to 625 to 921 tubers for the new type. The highest number of tubers was produced when both varieties were planted at the 6-inch depth. The high tuber production for the new type could be attributed to a higher number of stems, suggesting greater ability to produce rhizomes and possible expansion to cover a wider area within a short time.

Study 3 The new type plants harvested on June 15 had a greater number of stems and plant height compared to the true type (Fig. 4). The number of stems and height peaked during late August for both the true and new type variety. The decrease in the number of stems starting early September indicated plant maturity towards the end of the season and container effects. These results suggest that the new type YNS is capable of forming large patches early in the season and possibly severely competing with onions compared to the true type. This matches field observations in locally infested fields. Relatively higher number of stems for the new type resulted in greater root weight and the number of tubers produced per pot compared to the true type (Fig. 5). The number of tubers for the true type variety ranged from 28 to 744/pot for plants harvested June 15 and September 17, respectively. Respective tuber number for the new type variety was 112 to 718/pot. These studies will be repeated for two more years to confirm the results and complement ongoing greenhouse studies to evaluate local YNS varietal response to herbicide dose.

References Felix, J., and J. Ishida. 2009. Yellow nutsedge tuber production in response to depth of

emergence. Malheur Experiment Station Annual Report 2008. Oregon State University Special Report 1094:185-190.

Flora of North America. FNA Vol. 23 Page 168-169. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242357656


http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242357656

Figure 1. Yellow nutsedge (Cyperus esculentus) var leptostachyus (top left) and var. heermannii (top right and bottom picture) in the Treasure Valley of eastern Oregon. Photos by Dr. Joel Felix, Oregon State University, Malheur Experiment Station, Ontario, OR.

Cyperus esculentus var. leptostachyus Cyperus esculentus var. heermannii

Cyperus esculentus var. heermannii


True type (2-inch)

Y=-4930.7+80.9X-0.32X2

R2=0.92; P=0.007

Julian date (April 20 to May, 9, 2012)

105 110 115 120 125 130

Em

erge

nce

(%)

0

20

40

60

80

100

True type; 2-inch

True type; 4-inch

New type; 2-inch

New type; 4-inch

True type (4-inch)

Y=-5659.8+92.4X-0.4X2

R2=0.97; P=0.001

New type (4-inch)

Y=1263.6-23.5X+0.1X2

R2=0.99; P<0.0001

New type (2-inch)

Y=1260.4-25.1X+0.1X2

R2=0.97; P=0.0012

Figure 2. Yellow nutsedge emergence in response to depth of tuber placement for Cyperus esculentus var. leptostachyus (true type) and Cyperus esculentus var. heermannii (new type) at the Malheur Experiment Station, Ontario, OR, 2012.


New typeY=736.2+29.6-1.9X2; R2=0.60; P=0.40

Tuber placement depth (inches)

0 5 10 15 20

Num

ber o

f tub

ers/

1,55

8 in

3 of s

oil

0

200

400

600

800

1000

True type

New Type

True typeY=406.2+47.3-2.5X2; R2=0.12; P=0.87

Figure 3. Tuber production in response to depth of placement for Cyperus esculentus var. leptostachyus (true type) and Cyperus esculentus var. heermannii (new type) at the Malheur Experiment Station, Ontario, OR, 2012.


True typeY=-283.7+2.7X-0.006X2

R2=0.66; P=0.02

Julian date (June 15 to October 31, 2012)

140 160 180 200 220 240 260 280 300

Num

ber o

f ste

ms/

pot

0

20

40

60

80

100Stems; True type

Stems; New type

New type

Y=-155.8+1.7X-0.003X2

R2=0.45; P=0.12

New type

Y=-31.9+0.4X-0.0008X2

R2=0.84; P=0.002


140 160 180 200 220 240 260 280 300

Pla

nt h

eigh

t (in

ches

)

8

10

12

14

16

18

20

22Plant height; True type

Plant height; New type

True type

Y=-29.9+0.5X-0.0007X2

R2=0.77; P=0.006

Figure 4. Yellow nutsedge number of stems and plant height for biweekly harvest of Cyperus esculentus var. leptostachyus (true type) and Cyperus esculentus var. heermannii (new type) at the Malheur Experiment Station, Ontario, OR, 2012.


New type

Y=0.8-0.0057X-0.000021X2

R2=0.55; P=0.06


140 160 180 200 220 240 260 280 300

Roo

t wei

ght (

oz/p

ot)

0.0

0.2

0.4

0.6

0.8

1.0

1.2Root weight (True type)

Root weight (New type)

True type

Y=-0.06-0.0011X-0.000021X2

R2=0.74; P=0.009

New type

Y=-261.9+0.8X+0.0095X2

R2=0.91; P=0.0002


140 160 180 200 220 240 260 280 300

Num

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f tub

ers/

pot

-200

0

200

400

600

800

1000Tubers (True type)

Tubers (New type)

True type

Y=-1054.5+7.2X-0.004X2

R2=0.83; P=0.002

Figure 5. Total number of yellow nutsedge tubers for Cyperus esculentus var. leptostachyus (true type) and Cyperus esculentus var. heermannii (new type) plants harvested biweekly at the Malheur Experiment Station, Ontario, OR, 2012.


HERBICIDE COMBINATIONS AND ADJUVANTS FOR YELLOW NUTSEDGE CONTROL IN GLYPHOSATE-RESISTANT SUGAR BEET Joel Felix and Joey Ishida, Malheur Experiment Station, Oregon State University, Ontario, OR, 2012 Introduction Weed control in sugar beet improved after the introduction of glyphosate-resistant hybrids for commercial production in 2008. Growers are now able to control most annual broadleaf and grassy weeds better compared to the micro-rate herbicide program era. However, control for yellow nutsedge (Cyperus esculentus) remains a challenge for sugar beet growers in the Treasure Valley of eastern Oregon and southwestern Idaho. The predominant use of glyphosate as the herbicide of choice for weed control in glyphosate-resistant crops has resulted in the selection of resistant weed biotypes in many states. It is important for growers in the Treasure Valley to be aware of the selection pressure exerted on weeds by the continuous use of glyphosate alone to manage weeds. Growers need to be proactive in their approach to weed management in glyphosate-resistant sugar beets. The ideal weed management program needs to include herbicides with different modes of action. The weed management research program at the Malheur Experiment Station strives to develop herbicide combinations for effective management of weeds. Extra effort is devoted to develop herbicide programs for effective management of yellow nutsedge. We also need to develop herbicide combinations for the management of kochia in sugar beet to avert selection for glyphosate resistance. Glyphosate-resistant kochia populations have been confirmed in Kansa, Nebraska, South and North Dakota, Colorado, and southern Alberta in Canada.

Materials and Methods Field studies were established in 2012 at the Malheur Experiment Station, Ontario, Oregon to evaluate herbicide combinations, adjuvants, and application timing to improve yellow nutsedge control in glyphosate-resistant sugar beets. Fertilizer was applied during fall 2011 to provide 50, 40, and 60 lb/acre of nitrogen, phosphate, and sulfur, respectively. The field was moldboard plowed, groundhogged, and 22-inch-wide beds formed. The beds were harrowed and reshaped on April 10, 2012. Two trials had treatments arranged in randomized complete block designs with four replications. Individual plots were 7.33 ft wide (4 rows) by 27 ft long. Soil was Owyhee silt loam (pH 6.9, 1.75 percent organic matter, and cation exchange capacity [CEC] 21 meq/kg). The treatments are listed in Tables 1 and 4.

Herbicide Combinations and Adjuvants for Yellow Nutsedge Control in Glyphosate Resistant Sugar Beet 184

Roundup Ready® sugar beet hybrid BTS 27RR20 was planted on April 11, 2012, using tractor-mounted flexi-planter units with double-disc furrow openers and cone seeders fed from a spinner divider that uniformly distributed the seeds within the row. Sugar beet seeds were dropped at 5-inch spacing within the row. Terbufos at 1.11 lb ai/acre (Counter® 15G at 7.4 lb/acre) was applied on April 13. Plants were sidedressed with urea on May 30, 2012 to supply 200 lb nitrogen/acre. The study was furrow irrigated on a calendar schedule to maintain moisture in the top 12 inches of the soil profile. Irrigation scheduling began on May 9 and ended on August 30, 2012 with each event lasting 24 hours. Preventative sprays for powdery mildew were done on July 9 and August 28 using Inspire™ (difenoconazole) fungicide at 7 oz/acre plus sulfur at 5 lbs/acre. Herbicide treatments were applied using a CO2-pressurized backpack sprayer with a boom equipped with four 8002EVS Teejet nozzles calibrated to deliver 12 gal/acre of spray solution at 35 psi and 3 mph. Early POST treatments (sugar beet at 2-leaf stage) were applied on May 9 followed by a second POST application (sugar beet at 6-leaf stage) on May 31, 2012. Plants within each plot were evaluated visually for crop injury and weed control on June 21 and August 10, 2012. Evaluations were based on a scale of 0 percent (no crop injury or no weed control) to 100 percent (complete crop kill or complete weed control). Sugar beets were harvested by hand on October 2 from 10 ft of the two center rows. Sugar beet weight from each plot was corrected for tare to estimate yield. Sugar content and other sugar yield variables were determined in a laboratory at the Amalgamated Sugar Factory in Paul, Idaho. Data were subjected to analysis of variance using SAS and means compared using LSD at P = 0.05 percent.

Results and Discussion Herbicide Combination Study

There was no sugar beet injury observed from any of the evaluated treatment combinations in these studies (Tables 1 and 4). Early season yellow nutsedge control was evaluated on June 21 (21 days after the last herbicide application) and ranged from 73 to 97 percent (Table 1). The highest control (91 to 97%) was obtained with treatments that included Dual Magnum® at 1.27 lb ai/acre or Outlook® at 0.98 lb ai/acre applied in tank mixtures with glyphosate. These results are consistent with our findings in 2011. The tank mix of Nortron® at 0.5 lb ai/acre plus glyphosate at 0.77 lb ae/acre applied at the two-leaf stage followed by glyphosate at 0.77 lb ae/acre when sugar beet plants were at the six-leaf stage provided 88 percent control. The lowest yellow nutsedge control was observed when standalone glyphosate at 0.77 lb ae/acre was applied at the two- and six-leaf stages. Control for common lambsquarters and kochia at 21 days after the last herbicide application was greater than 97 percent across treatments. The treatments provided complete control of pigweed species. Estimates of late season weed control was made 71 days after the last herbicide application (Table 2). The control of yellow nutsedge followed a similar trend as that obtained at 21 days after herbicide application. Yellow nutsedge control was consistently highest for treatments that included Dual Magnum or Outlook at the two- and six-leaf application timings. Late season control for common lambsquarters, pigweed species, hairy nightshade, and barnyardgrass ranged from 94 to 100 percent across herbicide treatments.


The treatments did not affect sugar beet plant stand (Table 3). Sugar beet root yield ranged from 29.1 to 50 tons/acre. The lowest root yield and estimated recoverable sugar was obtained when glyphosate at 0.77 lb ae/acre was applied alone to plants that were at the two- and six-leaf stages. Percent sucrose content was similar across herbicide treatments. Once again these results are consistent with our findings in 2011 when treatments that included soil-active herbicides provided the highest yellow nutsedge control and root yield. Adjuvants Study

Tank mixes of glyphosate at 1.13 lb ae/acre with either ammonium sulfate (AMS), Zenith, Array, or AMS plus nonionic surfactant (NIS) provided the highest early season yellow nutsedge control (Table 4). Application of glyphosate at 0.77 lb ae/acre provided the lowest yellow nutsedge control among the herbicide treatments. The treatments provided complete control for common lambsquarters, kochia, and barnyardgrass. Late season yellow nutsedge control ranged from 71 to 89 percent with glyphosate applied at 0.77 lb ae/acre providing the lowest control (Table 5). Control for common lambsquarters, kochia, and barnyardgrass at 71 days after the last herbicide application ranged from 86 to 98 percent. The root yield was similar across treatments and ranged from 38.3 to 48.4 tons/acre (Table 6). Percent sucrose content and the estimated recoverable sugar was similar across herbicide treatments. The results suggested that control for yellow nutsedge was influenced more by the glyphosate rate than the adjuvants. Previous results had indicated improved yellow nutsedge control with the tank mixes that included AMS and NIS.


Table 1. Early season (June 21, 2012) weed control in Roundup-resistant sugar beet with and without soil active herbicides at the Malheur Experiment Station, Ontario, OR, 2012.

Weed control**

Treatment* Rate Timing Crop injury

Yellow nutsedge

Common lambsquarter

s Kochia

Pigweed species

------------------------------- % ------------------------------- Untreated 0 a 0 e 0 c 0 c 0 b Nortron 0.5 lb ai/a 2-leaf 0 a 88 c 98 b 98 ab 100 a Roundup PowerMax 0.77 lb ae/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Nortron 1 lb ai/a 2-leaf 0 a 83 c 100 a 100 a 100 a Roundup PowerMax 0.77 lb ae/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 0 a 73 d 97 b 97 b 100 a Roundup PowerMax 0.77 lb ae/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 0 a 84 bc 100 a 100 a 100 a Roundup PowerMax 1.13 lb ae/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 0 a 97 a 100 a 100 a 100 a Dual Magnum 1.27 lb ai/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Dual Magnum 1.27 lb ai/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 0 a 91 abc 100 a 100 a 100 a Sustain 1.04 lb ai/a 2-leaf Dual Magnum 1.27 lb ai/a 6-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Sustain 1.04 lb ai/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 0 a 93 ab 100 a 100 a 100 a Outlook 0.98 lb ai/a 6-leaf Roundup PowerMax 1.13 lb ae/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 0 a 97 a 100 a 100 a 100 a Outlook 0.98 lb ai/a 2-leaf Roundup PowerMax 1.13 lb ae/a 6-leaf Outlook 0.98 lb ai/a 6-leaf

* All treatments included ammonium sulfate (AMS) at 2.5 percent v/v. **Means within a column followed by same letter do not significantly differ (P = 0.05, Student-Newman-Keuls).


Table 2. Late season (August 10, 2012) weed control in Roundup-resistant sugar beet with and without soil-active herbicides at the Malheur Experiment Station, Ontario, OR, 2012. Weed control**

Treatment* Rate Timing Yellow nutsedge


Pigweed species

Hairy nightshade Barnyardgrass

% Untreated 0 e 0 d 0 c 0 b 0 b Nortron 0.5 lb ai/a 2-leaf 81 c 96 bc 97 ab 100 a 94 a Roundup PowerMax 0.77 lb ae/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Nortron 1 lb ai/a 2-leaf 78 c 100 a 100 a 100 a 95 a Roundup PowerMax 0.77 lb ae/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 66 d 95 c 97 b 94 a 99 a Roundup PowerMax 0.77 lb ae/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 80 c 100 a 100 a 99 a 93 a Roundup PowerMax 1.13 lb ae/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 98 a 98 ab 98 ab 100 a 100 a Dual Magnum 1.27 lb ai/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Dual Magnum 1.27 lb ai/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 93 ab 100 a 100 a 100 a 98 a Sustain 1.04 lb ai/a 2-leaf Dual Magnum 1.27 lb ai/a 6-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Sustain 1.04 lb ai/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 89 b 100 a 100 a 95 a 95 a Outlook 0.98 lb ai/a 6-leaf Roundup PowerMax 1.13 lb ae/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 99 a 100 a 100 a 100 a 100 a Outlook 0.98 lb ai/a 2-leaf Roundup PowerMax 1.13 lb ae/a 6-leaf Outlook 0.98 lb ai/a 6-leaf * All treatments included ammonium sulfate (AMS) at 2.5 percent v/v. **Means within a column followed by same letter do not significantly differ (P = 0.05, Student-Newman-Keuls).


Table 3. Late season (August 10, 2012) weed control in Roundup-resistant sugar beet with and without soil-active herbicides at the Malheur Experiment Station, Ontario, OR, 2012. Root and sugar yield**

Roots Root yield Sugar content Gross sugar ER Sugar

Treatment* Rate Timing no./acre tons/acre % lbs/acre lbs/acre Untreated 35311 b 5.3 c 4.16 b 394.5 c 337.1 c Nortron 0.5 lb ai/a 2-leaf 54895 a 45.4 a 18.43 a 16,668.1 a 14,315.0 a Roundup PowerMax 0.77 lb ae/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Nortron 1 lb ai/a 2-leaf 65281 a 40.8 a 18.47 a 15,038.0 a 12,942.2 a Roundup PowerMax 0.77 lb ae/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 62017 a 29.1 b 18.55 a 10,786.4 b 9,354.8 b Roundup PowerMax 0.77 lb ae/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 62610 a 41.7 a 18.51 a 15,339.1 a 13,126.6 a Roundup PowerMax 1.13 lb ae/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 57269 a 45.7 a 18.15 a 16,530.6 a 14,248.6 a Dual Magnum 1.27 lb ai/a 2-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Dual Magnum 1.27 lb ai/a 6-leaf Roundup PowerMax 0.77 lb ae/a 2-leaf 62017 a 49.0 a 18.46 a 18,065.5 a 15,518.2 a Sustain 1.04 lb ai/a 2-leaf Dual Magnum 1.27 lb ai/a 6-leaf Roundup PowerMax 0.77 lb ae/a 6-leaf Sustain 1.04 lb ai/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 55192 a 46.1 a 17.94 a 16,549.9 a 14,174.1 a Outlook 0.98 lb ai/a 6-leaf Roundup PowerMax 1.13 lb ae/a 6-leaf Roundup PowerMax 1.13 lb ae/a 2-leaf 64984 a 50.0 a 17.86 a 17,861.7 a 15,196.9 a Outlook 0.98 lb ai/a 2-leaf Roundup PowerMax 1.13 lb ae/a 6-leaf Outlook 0.98 lb ai/a 6-leaf * All treatments included ammonium sulfate (AMS) at 2.5 percent v/v. **Means within a column followed by same letter do not significantly differ (P = 0.05, Student-Newman-Keuls).


Table 4. Early season (June 21, 2012) weed control in Roundup-resistant sugar beet with glyphosate tank-mixed with different adjuvants at the Malheur Experiment Station, Ontario, OR, 2012. Weed control*

Treatment Rate Timing Crop injury

Yellow nutsedge

Common lambsquarters Barnyardgrass Kochia

---------------------------------------- % ---------------------------------------- Untreated 0 a 0 e 0 b 0 b 0 b Roundup Weathermax 0.77 lb ae/a 2-leaf 0 a 78 cd 100 a 100 a 100 a AMS 2.5 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 0 a 91 ab 100 a 100 a 100 a AMS 2.5 % v/v 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 0 a 73 d 100 a 100 a 100 a Sustain 1.04 lb ai/a 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Sustain 1.04 lb ai/a 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 0 a 78 cd 100 a 100 a 100 a Zenith 2.25 lb ai/a 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Zenith 2.25 lb ai/a 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 0 a 80 bcd 100 a 100 a 100 a Array 1.08 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Array 1.08 % v/v 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 0 a 91 ab 100 a 100 a 100 a Zenith 2.25 lb ai/a 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf Zenith 2.25 lb ai/a 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 0 a 93 a 100 a 100 a 100 a Array 1.08 % v/v 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf Array 1.08 % v/v 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 0 a 88 abc 100 a 100 a 100 a AMS 2.5 % v/v 2-leaf NIS (R-11) 0.25 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf NIS (R-11) 0.25 % v/v 6-leaf

*Means within a column followed by same letter do not significantly differ (P = 0.05, Student-Newman-Keuls).


Table 5. Late season (August 10, 2012) weed control in Roundup-resistant sugar beet with glyphosate tank-mixed with different adjuvants at the Malheur Experiment Station, Ontario, OR, 2012. Weed control*

Treatment Rate Timing Yellow nutsedge


Pigweed species Barnyardgrass

----------------------------------- % ----------------------------------- Untreated 0 c 0 b 0 b 0 b Roundup Weathermax 0.77 lb ae/a 2-leaf 71 b 95 a 90 a 95 a AMS 2.5 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 80 a 98 a 98 a 96 a AMS 2.5 % v/v 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 74 b 95 a 88 a 91 a Sustain 1.04 lb ai/a 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Sustain 1.04 lb ai/a 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 84 a 98 a 96 a 99 a Zenith 2.25 lb ai/a 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Zenith 2.25 lb ai/a 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 83 a 98 a 86 a 95 a Array 1.08 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Array 1.08 % v/v 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 81 a 94 a 89 a 88 a Zenith 2.25 lb ai/a 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf Zenith 2.25 lb ai/a 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 84 a 96 a 96 a 95 a Array 1.08 % v/v 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf Array 1.08 % v/v 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 89 a 98 a 95 a 96 a AMS 2.5 % v/v 2-leaf NIS (R-11) 0.25 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf NIS (R-11) 0.25 % v/v 6-leaf * Means within a column followed by same letter do not significantly differ (P = 0.05, Student-Newman-Keuls)


Table 6. Sugar beet root yield and sugar content in response to glyphosate tank-mixed with different adjuvants at the Malheur Experiment Station, Ontario, OR, 2012. Root and sugar yield* Roots Yield Sugar content Gross sugar ERS Treatment Rate Timing no./acre ton/acre % lbs/acre lbs/acre Untreated 1,7210 b 6.7 b 13.85 a 1,934.1 b 1,660.6 b Roundup Weathermax 0.77 lb ae/a 2-leaf 63,204 a 45.5 a 18.39 a 16,743.8 a 14,405.6 a AMS 2.5 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 63,204 a 48.4 a 18.27 a 17,675.0 a 15,220.5 a AMS 2.5 % v/v 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 63,204 a 39.8 a 18.63 a 14,807.4 a 12,738.2 a Sustain 1.04 lb ai/a 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Sustain 1.04 lb ai/a 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 67,951 a 44.2 a 18.27 a 16,150.1 a 13,794.2 a Zenith 2.25 lb ai/a 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Zenith 2.25 lb ai/a 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 56,675 a 38.3 a 18.57 a 14,223.1 a 12,207.6 a Array 1.08 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf Array 1.08 % v/v 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 61,423 a 44.1 a 17.908 a 15,806.7 a 13,561.6 a Zenith 2.25 lb ai/a 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf Zenith 2.25 lb ai/a 6-leaf Roundup Weathermax 1.13 lb ae/a 2-leaf 56,675 a 42.6 a 17.855 a 14,630.6 a 12,623.1 a Array 1.08 % v/v 2-leaf Roundup Weathermax 1.13 lb ae/a 6-leaf Array 1.08 % v/v 6-leaf Roundup Weathermax 0.77 lb ae/a 2-leaf 58,159 a 45.5 a 18.013 a 16,394.6 a 14,019.6 a AMS 2.5 % v/v 2-leaf NIS (R-11) 0.25 % v/v 2-leaf Roundup Weathermax 0.77 lb ae/a 6-leaf AMS 2.5 % v/v 6-leaf NIS (R-11) 0.25 % v/v 6-leaf

* Means within a column followed by same letter do not significantly differ (P = 0.05, Student-Newman-Keuls).

Herbicide Combinations and Adjuvants for Yellow Nutsedge Control in the Treasure Valley 192

APPENDIX A. HERBICIDES AND ADJUVANTS Trade Name Common or Code Name Manufacturer AAtrex atrazine Syngenta Axial XL pinoxaden Syngenta Axial TBC pinoxaden + florasulam Syngenta Boundary s-metolachlor + metribuzin Syngenta Bronate Advanced bromoxynil Bayer CropScience Bronc ammonium sulfate Wilbur-Ellis Co. Buctril bromoxynil Bayer CropScience Caparol prometryn Syngenta Chateau flumioxazin Valent Dual, Dual Magnum s-metolachlor Syngenta Eradicane EPTC Gowan Company Eptam EPTC Gowan Company Ethotron SC ethofumesate United Phosphorus Goal, Goal 2XL, Goaltender oxyfluorfen Dow AgroSciences Herbimax petroleum hydrocarbons Loveland Products Huskie pyrasulfotole Bayer CropScience Integrity saflufenacil BASF Ag Products Kerb pronamide Dow AgroSciences Laudis tembotrione Bayer CropScience Lorox linuron Griffin LLC Matrix rimsulfuron Dupont Mor-Act paraffin based petroleum oil Wilbur-Ellis Co. Nortron ethofumesate Bayer CropScience Outlook dimethenamid-p BASF Ag Products Poast, Poast HC sethoxydim BASF Ag Products Progress, Progress Ultra desmedipham + phenmedipham Bayer CropScience + ethofumesate Prowl, Prowl H2O pendimethalin BASF Ag Products R-11 alkylphenol ethoxylate Wilbur-Ellis Co. Raptor imazamox BASF Ag Products Reflex fomesafen Syngenta Ro-Neet cycloate Stauffer Chemical Roundup, Roundup PowerMax glyphosate Monsanto Sandea halosulfuron Gowan Company Select, Select Max clethodim Valent Sencor metribuzin Bayer CropScience Sequence glyphosate + s-metolachlor Syngenta Sharpen saflufenacil BASF Ag Products Starane Ultra fluroxypyr Dow AgroSciences Status diflufenzopyr BASF Ag Products Stinger clopyralid Dow AgroSciences Touchdown glyphosate Syngenta Treflan trifluralin Dow AgroSciences UpBeet triflusulfuron Dupont Volunteer clethodim Tenkoz Warrant acetochlor Mondanto Yukon halosulfuron-methyl+dicamba Gowan Company Zidua pyroxasulfone BASF Ag Products

Appendix A. Herbicides and Adjuvants 193

APPENDIX B. INSECTICIDES, FUNGICIDES, AND NEMATICIDES Trade Name Common or Code Name Manufacturer

Acephate acephate various Admire imidacloprid Bayer CropScience Agri-Mek abamectin Syngenta Allegiance metalaxyl Bayer CropScience Aza-Direct azadirachtin Gowan Company Beleaf flonicamid FMC Corp. Bravo, Bravo Ultrex chlorothalanil Syngenta Captan N-trichloromethylthio-4- various cyclohexene-1, 2-dicarboximide Capture 2EC bifenthrin FMC Carzol formetanate hydrochloride Gowan Company Counter 20 CR, Counter 15G terbufos BASF Ag Products Cyazypyr cyantaniliprole DuPont Dithane mancozeb Dow AgroSciences Dividend XL difenoconazole + mefenoxam Syngenta Enable fenbuconazole Dow AgroSciences Gaucho imidacloprid Gowan Company Headline pyraclostrobin BASF Ag Products Inspire difenoconazole Syngenta Knack pyriproxyfen Valent Lannate methomyl DuPont Lorsban, Lorsban 15G chlorpyrifos Dow AgroSciences M-Pede potassium salts of fatty acids Dow AgroSciences Movento spirotetramat Bayer CropScience MSR oxydemeton-methyl Gowan Company Mustang zeta-cypermethrin FMC Mycotol O Beauveria bassiana BioWorks, Inc. Neemazad azadirachtin Certis USA Nexter pyridaben Gowan Company Proline prothioconazole Bayer CropScience Quadris Opti azoxystrobin Syngenta Radiant spinetoram Dow AgriSciences Regent fipronil BASF Ag Products Requiem chenopodium ambrosioides AgraQuest Ridomil MZ58 metalaxyl Syngenta Success spinosad Dow AgroSciences Tanos famoxadone + cymoxanil Du Pont Telone C-17, Telone II dichloropropene + chloropicrin Dow AgroSciences Temik 15G aldicarb Bayer Cropscience Tops-MZ thiophanate-methyl Bayer Cropscience Topsin M thiophanate-methyl United Phosphorus, Inc. Trilogy extract of neem oil Certis USA Ultiflora milbemectin Gowan Company Vapam metam sodium Amvac Venom dinotefuran Valent Vydate, Vydate L oxamyl DuPont Warrior cyhalothrin Syngenta

Appendix B. Insecticides, Fungicides, and Nematicides 194

APPENDIX C. COMMON AND SCIENTIFIC NAMES OF CROPS, FORAGES, AND FORBS Common names Scientific names alfalfa Medicago sativa barestem biscuitroot Lomatium nudicaule barley Hordeum vulgare basalt milkvetch Astragalus filipes bluebunch wheatgrass Pseudoroegneria spicata blue penstemon Penstemon cyaneus corn, sweet corn Zea mays corn lily Veratrum californicum dry edible beans Phaseolus spp. fernleaf biscuitroot, desert parsley Lomatium dissectum gooseberryleaf globemallow Sphaeralcea grossulariifolia Gray’s lomatium Lomatium grayi Great Basin wildrye Leymus cinereus hicksii yew Taxus x media hotrock penstemon, scabland penstemon Penstemon deustus Hayden’s cymopterus Cymopterus bipinnatus miscanthus Miscanthus giganteus nineleaf desert parsley Lomatium triternatum onion Allium cepa Pacific yew Taxus brevifolia parsnipflower buckwheat Eriogonum heracleoides poplar trees, hybrid Populus deltoides x P. nigra potato Solanum tuberosum red globemallow Sphaeralcea coccinea Rocky Mountain beeplant Cleome serrulata royal penstemon Penstemon speciosus Russian wildrye Psathyrostachys juncea Searls’ prairie clover Dalea searlsiae sharpleaf penstemon, sandhill penstemon Penstemon acuminatus Siberian wheatgrass Agropyron fragile silvery lupine Lupinus argenteus smallflower globemallow Sphaeralcea parvifolia soybeans Glycine max spearmint, peppermint Mentha spp. sugar beet Beta vulgaris sulfur-flower buckwheat Eriogonum umbellatum teff Eragrostis tef thickleaf beardtongue Penstemon pachyphyllus Thurber’s needlegrass Achnatherum thurberianum triticale Triticum x Secale western prairie clover Dalea ornata western yarrow Achillea millifolium wheat Triticum aestivum

Appendix C. Common and Scientific Names of Crops, Forages, and Forbs 195

APPENDIX D. COMMON AND SCIENTIFIC NAMES OF WEEDS Common names Scientific names annual sowthistle Sonchus oleraceus barnyardgrass Echinochloa crus-galli black medic Medicago lupulina blue mustard Chorispora tenella common lambsquarters Chenopodium album common mallow Malva neglecta dodder Cuscuta spp. downy brome Bromus tectorum field bindweed Convolvulus arvensis flixweed Descurainia sophia green foxtail Setaria viridis hairy nightshade Solanum sarrachoides kochia Kochia scoparia lady’s thumb Polygonum persicaria large crabgrass Digitaria sanguinalis Powell amaranth Amaranthus powellii prickly lettuce Lactuca serriola prostrate knotweed Polygonum aviculare redroot pigweed Amaranthus retroflexus Russian knapweed Acroptilon repens shepherd’s purse Capsella bursa-pastoris wild oat Avena fatua whitetop, hoarycress Cardaria draba yellow nutsedge Cyperus esculentus

Appendix D. Common and Scientific Names of Weeds 196

APPENDIX E. COMMON AND SCIENTIFIC NAMES OF DISEASES, PHYSIOLOGICAL DISORDERS, INSECTS, AND NEMATODES Common names Scientific names Diseases Alternaria fungus Alternaria spp. Aphanomyces root rot Aphanomyces euteiches anthracnose Colletotrichum trifolii, bacterial wilt Clavibacter michiganensis fusarium wilt Fusarium oxysporum iris yellow spot virus onion black mold Aspergillus niger onion neck rot, (gray mold) Botrytis allii onion plate rot Fusarium oxysporum phytophthora root rot Phytophthora medicaginis powdery mildew Leveillula taurica potato late blight Phytophthora infestans rust Puccinia sherardiana verticillium wilt Verticillium spp. Physiological disorders iron deficiency onion translucent scale potato jelly ends potato sugar ends Insects alfalfa weevil Hypera postica cereal leaf beetle Oulema melanopus lygus bug Lygus hesperus onion maggot Delia antiqua onion thrips Thrips tabaci pea aphid Acyrthosiphon pisum seed corn maggot Delia platura spidermite Tetranychus spp. spotted alfalfa aphid Therioaphis maculate stinkbug Pentatomidae spp. sugar beet root maggot Tetanops myopaeformis western flower thrips Franklinella occidentalis willow sharpshooter Graphocephala confluens (Uhler) Nematodes alfalfa stem nematode Ditylenchus dipsaci northern root-knot nematode Meloidogyne hapla

Appendix E. Common and Scientific Names of Diseases, Physiological Disorders, Insects, and Nematodes 197

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