A Comprehensive Guide to Wheat Management in Kentucky

8/14/2019 A Comprehensive Guide to Wheat Management in Kentucky

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EXTENSION

Agriculture and Natural Resources Family and Consumer Sciences 4-H Youth Development Community and Leadership Development

COOPERATIVE EXTENSION SERVICE UNIVERSITY OF KENTUCKY COLLEGE OF AGRICULTURE, LEXINGTON, KY, 40546

I D - 1 2 5

A Comprehensive Guide to

Wheat

Managementin Kentucky


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AcknowledgmentsThe authors acknowledge the ollowing or their assistance with this publication:

Photographs in this publication are keyed to the ollowing sources:University o Kentucky College o Agriculture

Ricardo Bessin8-1, 8-6, 8-7William Bruening2-3, 2-4, 3-1, 3-2, 3-6, 5-4John Grove4-2, 5-5, 5-6 (right)James Herbek11-1 to 11-7Don Hershman7-2 to 7-16Cam Kenimer3-5Chad Leeall remaining photosJames Martin6-6, 6-14Sam McNeill9-1Tom Miller3-7Bill Mesner6-8, 6-9, 6-10Jaclyn Mundell7-1

Greg Schwab5-6 (let), 5-7, 5-8

Other ContributorsPhil Needham4-3Joe Nichols10-1

Kansas State University College o Agriculture6-4, 6-11, 6-12, 6-13, 8-2, 8-3, 8-4, 8-5, 8-8, 8-9, 8-10, 11-8 to 11-13

Michigan State University College o Agriculture6-2, 6-3, 6-7

Some material contained in this publication was adapted with permission rom: Alley, et al., IntensiveSot Red Winter Wheat Production (No. 424-803), Virginia Cooperative Extension Service, Blacksburg,Virginia (1993), and Shroyer, James P., et al., Spring Freeze Injury to Kansas Wheat (C-646), AgriculturalExperiment Station and Cooperative Extension Service, Kansas State University, Manhattan, Kansas(March 1995).


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A Comprehensive Guide to

Wheat

Managementin KentuckyCover: Pembroke variety o sot red winter wheat developed by theUniversity o Kentucky with unding rom the Kentucky Small GrainsGrowers Association.

AuthorsPlant and Soil SciencesChad Lee and James Herbek, Co-editors, William Bruening, J. D. Green,

John Grove, James R. Martin, Lloyd Murdock, Greg Schwab, David Van SanordPlant PathologyDonald E. HershmanEntomologyDouglas W. Johnson, Lee TownsendBiosystems and Agricultural EngineeringSam McNeill, Mike Montross, Doug OverhultsAgricultural EconomicsRichard Trimble

1. Introduction .................................................................................................................. 4

2. Growth and Development .............................................................................................. 6

3. Cultural Practices ..........................................................................................................13

4. Planting and Drill Calibration ....................................................................................... 20

5. Fertilizer Management ................................................................................................ 256. Weed Management ...................................................................................................... 30

7. Disease Management ................................................................................................... 42

8. Insect Pests ................................................................................................................. 55

9. Economics of the Intensively Managed Wheat Enterprise ............................................... 60

10. Harvesting, Drying and Storing Wheat ......................................................................... 66

11. Supplement ................................................................................................................. 70

FundingKentucky Small Grain Growers AssociationUniversity o Kentucky Cooperative Extension ServiceUniversity o Kentucky Wheat Science IPM Working Group

DevelopmentUniversity o Kentucky Wheat Science IPM Working Group

Mention or display o a trademark, proprietary product, or rm in text or gures does not constitute an endorsement and doesnot imply approval to the exclusion o other suitable products or rms.


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4 I n t r o D u c t I o n

Section 1

IntroductionChad Lee, James Herbek, and Richard L. Trimble

The sot red winter wheat (Triticum aestivum L.) grown inKentucky provides our or cookies, cakes, pastries, and

crackers and is the ourth most valuable cash crop in thestate (Figure 1-1). Winter wheat has been an integral parto crop rotation or Kentucky armers. Wheat is normallyharvested in June in Kentucky and provides an importantsource o cash ow during the summer months. Severaltrends should be examined when considering the economicpotential o wheat production in the state (seeSection 9

Economics of the Intensively Managed Wheat Enterprise).Improvements in varieties and adoption o intensive

wheat management practices have resulted in dramaticallyincreased wheat yields. Prior to 1987, the highest average

yield achieved in Kentucky was 42 bushels per acre; since1987, averages have been at least 49 bushels per acre in allbut two years (Figure 1-2). State average yields have been59 bushels per acre or the past decade and 62 bushels peracre or the past ve years. State averages were above 70bushels per acre in 2006 and 2008. Continued increasesin yield help to keep wheat in the crop rotation.

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illionDollars($US)

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SoybeanGrain sorghumTobacco

Figure 1-1. Kentucky crop values according to the Kentucky AgriculturalStatistics Service.

Photo 1-1. Sot red winter wheat (Triticum aestivum) grown in Kentuckyis a valuable commodity and an important component to crop rotations.It also provides our or cookies, cakes, pastries, and crackers, and eed orlivestock.


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5I n t r o D u c t I o n

18 Steps or Maximum Winter Wheat Yields

1. Test soil to determine ertility o eld.

2. Apply P, K, and lime according to soil test and University o Kentucky recommendations.

3. Select several high-yielding, disease-resistant, winter-hardy wheat varieties.

4. Calibrate the drill or other seeding equipment.

5. For conventional tillage, prepare a good seedbed.6. For no-tillage, use a contact herbicide.

7. Use 30 lb/A Nitrogen in all as residual or applied.

8. Plant rom Oct. 10 to Oct. 30.

9. Plant in 4- to 8-inch row spacings. Tramlines may be established at this time or subsequentapplications.

10. Seed 35 (up to 40 or no-till) seeds/square oot o high quality viable seed.

11. Apply insecticide as needed or insect control (all and spring).

12. Check stand density near mid-February when winter survival can be rated.

a) I stand is adequate (25 plants/square oot or more), apply 30 to 40 lb o nitrogen mid-to-late February.

b) I stand is thin (less than 25 plants/square oot), apply 40 to 50 lb o nitrogen mid-to-

late February.13. Apply an additional 50 to 60 lb nitrogen at Feekes 5 (mid-March).

14. Use proper weed control measures (all and spring).

15. Apply ungicides as needed or disease control during the growing season.

16. Harvest on time at optimum grain moisture (13 to 15%).

17. Provide and prepare adequate, sae storage space.

18. Market wisely or optimum prots.

Figure 1-3. Kentucky planted and harvested wheat acres according toKentucky Agricultural Statistics Service.

he average yield o wheat trendhas been upward, but the numbero acres o wheat planted in the statehas declined since 1981. Harvestedacres were 680,000 in 1981 and were

460,000 in 2008 (Figure 1-3). Fluc-tuation in wheat acres harvested isa unction o government programs,crop condition and economics.

Tis publication will help you usewheat management practices to im-prove the competitiveness o wheat in

your crop rotation. Tere is no singlebest wheat management prescriptionor all circumstances, but this com-prehensive publication explains theprinciples o wheat growth and man-agement so you can make decisions

appropriate to your situation. hispublication also will help troubleshootproblems encountered during thegrowing season. I you use and adoptthe ollowing principles and practices,

you should see increased yields, higherprots, and improved environmentalprotection rom your wheat elds.

Te important steps or intensive wheat managementcan be summarized in 18 steps. Te application o thesesteps at the proper stage o growth and time o year is thebasis or obtaining maximum and ecient wheat yields.(See Winter Wheat Calendar[ID-125A].)

19501940 1960 1970 1980 1990 2000

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Figure 1-2. Kentucky average wheat yields according to Kentucky Agri-cultural Statistics Service.

19861981 1991 1996 2001 2006

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6 G r o w t h a n D D e v e l o p m e n t

Wheat responds best to inputs at certain stages o plantdevelopment. Tereore, it is important to understand

wheat development and recognize wheat growth stages inorder to properly time applications o pesticides, nitrogen,and other inputs.

Wheat plants progress through several growth stages,which are described in terms o developmental events.Wheat plant growth and development can be broadly divid-ed into the ollowing progressive stages: germination/seed-ling emergence, ti llering, stem elongation, boot, heading/anthesis, and grain-ll/ripening. Several diferent systems

have been developed to identiy wheat growth stages. Tesesystems use a numerical designation or the development orormation o specic plant parts. Te two most widely usedmethods or identication o wheat growth stages are theFeekes scale and the Zadoks scale. Te Feekes scale is thetraditional, most common scale and has been widely usedby Kentucky growers. Developmental stages are designatedon a scale o 1 (seedling growth) through 11 (ripening). TeZadoks scale is much more descriptive o various stageso development. It uses a two-digit system or wheat plantdevelopment, divided into 10 primary stages, each o which Photo 2-1. Wheat at about Feekes 2 (Zadoks 21) in corn residue.

is divided into 10 secondary stages, or a total o 100 stages.Te Zadoks scale goes rom primary stage 00 (dry seed) to90 (ripening). Both the Zadoks and Feekes scales are shownor comparison (Figure 2-1 and able 2-1).

Germination and Seedling GrowthAdequate temperature and moisture are needed or

wheat seeds to germinate. Wheat seeds germinate at tem-peratures o 39F or higher; temperatures between 54 and77F are considered optimum or rapid germination andgrowth. Germination begins when the seed imbibes waterrom the soil and reaches 35 to 45 percent moisture on a dryweight basis. During germination, the seedling (seminal)roots, including the primary root (radicle), emerge rom theseed along with the coleoptile (leaike structure), whichencloses the primary leaves and protects the rst true leaduring emergence rom the soil. Te coleoptile extends tothe soil surace, ceases growth when it emerges, and the

Section 2

Growth and DevelopmentJames Herbek and Chad Lee


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Tillering Stem Extension Heading Ripening

1one

shoot

2tillering

begins

3tillers

formed

4leaf

sheathslengthen

5leaf

sheathsstronglyerected

6rst node

of stemvisible

7second

nodevisible

8last leaf

justvisible

9ligule of

last leafjust visible

10in

boot

10.1head

visible

10.5owering

(wheat)

11

Figure 2-1. The Feekes scale o wheat development.

rst true lea emerges rom its tip. Under avorable condi-tions, seedling emergence occurs within seven days. Untilthe rst lea becomes unctional, the seedling depends onenergy and nutrients stored in the seed.

Seedling growth begins with the emergence o the rstlea above the soil surace and continues until the nextstage, tillering. Normally three or more leaves develop inthe seedling stage beore tillering is initiated. Each new leacan be counted when it is over one-hal the length o the

older lea below it. During this phase the brous root systemdevelops more completely, helping plant establishment.

Te crown (a region o lower nodes whose internodesdo not elongate) is located between the seed and the soilsurace. It tends to develop at the same level, about one-halto one inch below the soil surace, regardless o plantingdepth. Leaves, tillers and roots (including the main rootsystem) develop rom the crown nodes. Te growing pointis located at the crown until it is elevated above the soilsurace at the stem elongation stage.

Tillering

Te tillering stage begins with the emergence o lateralshoots (tillers) rom the axils o the true leaves at the baseo the main stem o the plant. Te tillers are ormed romthe auxiliary buds located at each crown node. Primarytillers orm in the axils o the rst our or more true leaveso the main stem. Secondary tillers may develop rom thebase o primary tillers i conditions avor tiller develop-ment. A tiller may also develop rom the coleoptile node(coleoptilar tiller), but this occurs sporadically and itsappearance is dependent on genotype, planting practices,

and environmental conditions. At the base o each til ler isa sheath (small leaike structure) called the prophyll, romwhich the ti ller leaves emerge. Te prophyll acts like the co-leoptile and protects the auxiliary bud beore it elongates itsrst lea to become a tiller. Identiying the prophyll, whichencloses the base o the tiller, will help diferentiate tillerleaves rom the leaves on the main stem and rom othertillers. illering usually begins when the seedling planthas three or more ully developed leaves. illers depend

on the main stem or nutrition during their development.Once a til ler has developed three or more leaves, it becomesnutritionally independent o the main stem and orms itsown root system.

illers are an important component o wheat yieldbecause they have the potential to develop grain-bearingheads. In Kentucky, each plant normally develops two ormore tillers in the all when planted at optimum dates. Tetotal number o tillers eventually developed will not allproduce grain-bearing heads. Under recommended plantpopulations, usually two or three tillers, in addition to themain shoot, will produce grain. iller development occursin the all until low temperatures stop plant growth. In Ken-tucky, during the tillering stage, winter wheat goes throughthe winter months in a dormant condition in which plantgrowth (including tiller production) essentially ceases dueto cold temperature. iller production and developmentresumes in late winter/early spring with an increase intemperature as the plants break dormancy and resumegrowth. Due to cooler temperatures, late planted winterwheat may have little or no all til lering because o limitedseedling growth or because no wheat has emerged; lateplanted wheat will rely heavily on spring tiller development.


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Table 2-1. Wheat Growth Stages

Stage General DescriptionScale

Additional CommentsFeekes ZadoksGermination Dry seed 00

Start o imbibition 01Imbibition complete 03 Seed typically at 35 to 40% moisture.Radicle emerged rom seed (caryopsis) 05Coleoptile emerged rom seed (caryopsis) 07Lea just at coleoptile tip 09

SeedlingGrowth

First lea through coleoptile 1 10First lea unolded 112 leaves unolded 123 leaves unolded 134 leaves unolded 145 leaves unolded 156 leaves unolded 167 leaves unolded 178 leaves unolded 189 or more leaves unolded 19

Tillering Main shoot only 20Main shoot and 1 tiller 2 21Main shoot and 2 tillers 22

Main shoot and 3 tillers 23 Many plants will only have 2 or 3 tillers per plant at recommended populations.Main shoot and 4 tillers 24Main shoot and 5 tillers 25Main shoot and 6 tillers 3 26 Leaves oten twisting spirally.Main shoot and 7 tillers 27Main shoot and 8 tillers 28Main shoot and 9 tillers 29

StemElongation

Pseudostem erection 4-5 301st detectable node 6 31 Jointing stage2nd detectable node 7 323rd detectable node 334th detectable node 34 Only 4 nodes may develop in modern varieties.5th detectable node 356th detectable node 36Flag lea visible 8 37Flag lea ligule and collar visible 9 39

Booting Flag lea sheath extending 41 Early boot stage.Boot swollen 10 45Flag lea sheath opening 47First visible awns 49 In awned varieties only.

Head(Inorescence)Emergence

First spikelet o head vis ib le 10.1 50 o head visible 10.2 52 o head visible 10.3 54 o head visible 10.4 56Head completely emerged 10.5 58

Pollination(Anthesis)

Beginning o owering 10.51 60 Flowering usually begins in middle o head.10.52 Flowering completed at top o head.10.53 Flowering completed at bottom o head.

o owering complete 64Flowering completed 68

MilkDevelopment

Kernel (caryopsis) watery ripe 10.54 71Early milk 73Medium milk 11.1 75 Milky ripe.Late milk 77 Noticeable increase in solids o liquid endosperm when crushing the kernel between ngers

DoughDevelopment

Early dough 83Sot dough 11.2 85 Mealy ripe: kernels sot but dry.Hard dough 87

Ri pening Kerne l ha rd (hard to s plit by thumbnai l) 11.3 91 Physiologi cal maturi ty. No more dr y matte r a ccumulation.Kernel hard (cannot split by thumbnail) 11.4 92 Ripe or har vest. Straw dead.Kernel loosening in daytime 93Overripe 94Seed dormant 95Viable seed has 50% germination 96Seed not dormant 97Secondary dormancy 98Secondary dormancy lost 99

Sources: Conley, et al. 2003. Management o Sot Red Winter Wheat. IPM1022. Univ. o Missouri. Alley, et al. 1993. Intensive Sot Red Winter Wheat Production: A Management

Guide. Pub. 424-803. Virginia Coop. Extension. Johnson, Jr., et al. Arkansas Wheat Production and Management. MP404. Univ. o Arkansas. Coop. Ext. Serv.


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Spring tillers generally contributeless to yield potential than do alltillers. Consequently, all tillering isimportant or winter wheat to achievemaximum yield potential.

illers develop sequentially on aplant, resulting in a prioritization ordevelopment. he main stem andolder (rst-ormed) tillers have priorityto complete development and orm agrain-bearing head. Tis same prior-ity also exists regarding the size o thegrain-bearing head on the main stemand subsequent tillers.

Te number o tillers a plant devel-ops is not a constant and will vary be-cause o two actors: genetic potentialand environmental conditions. Some

varieties have a greater potential todevelop more tillers than others. il-lering is also a means or the plantto adapt to changing environmentalconditions. Plants are likely to pro-duce more tillers when environmental conditions such astemperature, moisture, and light are avorable, when plantpopulations are low, or when soil ertility levels are high.Under weather stress conditions such as high temperature,drought, high plant populations, low soil ertil ity, or pests,plants respond by producing ewer tillers or even abortinginitiated tillers. Rarely do more than ve auxiliary tillersorm and complete development on a plant. Although the

total number o til lers ormed per plant can vary consider-ably and be quite high, not all o the tillers remain produc-tive. Te later developing tillers usually contribute little to

yield. illers that emerge ater the th lea on the mainstem are likely to senesce (or die), abort, or not producea grain head. Very ew o the secondary tillers that ormusually develop a head unless conditions dictate a need.

As temperatures decrease below the minimum orplant growth in late al l/winter, winter wheat will becomedormant. Cooler temperatures induce cold hardiness inwheat plants to protect against cold injury and to help themsurvive the winter. During this period, the low tempera-tures initiate in the plant a physiological response called

vernalization. During vernalization, the plant convertsrom vegetative to reproductive growth and the reproduc-tive structures are developed. Because o this vernaliza-tion requirement, winter wheat produces only leaves orboth the main stem and tillers aboveground in the all inpreparation or winter. Te growing point and buds o boththe main stem and tillers remain belowground, insulatedagainst the cold winter temperatures. Once vernalizationrequirements are met, the growing point diferentiates and

Photo 2-2. Wheat eld at about Feekes 4 or 5 (Zadoks 30).

develops an embryonic head. At this time, wheat head sizeor total number o spikelets per head is determined. Neitherseedling growth nor tillering is required or vernalizationto occur. Tis process can begin in seeds as soon as theyabsorb water and swell. Hence, late planted wheat that hasnot emerged prior to winter should be adequately vernal-ized. Following vernalization, exposure to progressivelylonger photoperiods (longer day length periods) is necessaryto initiate and hasten reproductive development.

he vernalization requirement involves exposure tocooler temperatures or a required length o time. empera-tures below 50F are needed to induce cold hardening andsatisy vernalization requirements; temperatures o 37 to46F are considered sucient and most efective. Te re-quired length o low temperature exposure decreases withcolder temperatures and advanced plant development. Atsuciently low temperatures, most varieties in Kentuckyrequire three to six weeks o vernalization. Varieties alsodifer in their response to vernalizing temperature require-ments. Generally, early-maturing varieties require less time

to vernalize than later-maturing varieties.In some varieties, vernalization is afected by photope-riod, in which exposure o the wheat plant to short daysreplaces the requirement or low temperatures. Exposureo wheat to temperatures above 86F shortly ollowinglow temperatures can sometimes interrupt vernalization.Spring wheat varieties do not possess an absolute vernal-ization requirement. Reproductive development in mostspring varieties is induced by light and accumulated heatunits (growing degree days).


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Stem Elongation/JointingStem elongation is the next phase o growth (Feekes 4-9;

Zadoks 30-39). Te leaves o overwintering (dormant) wheatare generally short and lie rather at. As temperatures in-crease in the spring, the wheat plants break dormancy and

resume growth. Te lea sheaths grow quickly and give astrongly erect appearance known as a pseudostem (not areal stem) (Feekes 4-5; Zadoks 30). At this time, and priorto actual stem elongation, each main stem and tiller o the

young plant is a succession o leaves wrapped around eachother (i.e., a pseudostem). Te actual stem has not elongatedat this stage and the immature head (growing point) is stillbelow ground level but has started to advance above thecrown region. Te growing point is only about one-eightho an inch in length and has the appearance and shape oa very small pinecone.

As growth continues, stem elongation (jointing) occursas a result o internode elongation. Te embryonic head(growing point) in the main stem and each tiller that hasormed at the base o the plant begin to move up the stem.Te maximum possible number o kernels per head is de-termined at this time. Te plant al locates nutrients to themain stem and tillers with at least three leaves. Once theplant has jointed, typically no more potential head-bearingtillers will orm. However, i the growing point has beenkilled during stem elongation as a result o damage (physi-cal, reeze, pests) to the immature head and/or supportingstem, that main stem or tiller will die. As a result, the wheatplant will tend to compensate or this loss by developmento new shoots rom the base o the plant.

During stem elongation, the stem nodes and internodesemerge above the soil surace and become visible. Nodes areareas o active plant cell division rom which leaves, tillersand adventitious (crown) roots originate. Leaves originaterom the stem nodes above the soil surace and emerge asthe stem elongates. As jointing (stem elongation) occurs,the nodes swell, and they look and eel like bumps on thestem. Tis makes them easier to see or eel and easier tocount. An internode is the region between two successivenodes. During stem elongation, the internodes above thesoil surace elongate to orm the stem. Te elongated inter-node is hollow between the nodes. Wheat stems containseveral internodes which can be described as telescopic.

Prior to stem elongation, the nodes and internodes are allormed but are sandwiched together at the growing pointas alternating layers o cells destined to become the nodesand the internodes o a mature stem. When jointing isinitiated, these telescoped internodes begin to elongate,nodes appear one by one, and elongation continues untilhead emergence. When an internode has elongated toabout hal its nal length, the internode above it beginselongating. Tis sequence continues until stem elongationis complete, usually at head emergence. Each succeedingstem internode (rom the base to the top o the plant) be-

comes progressively longer. Te last elongated internodeis the peduncle, which supports the head. It accounts ora good proportion o the overall stem length. Plant heightcontinues to increase during stem elongation until theheads emerge. Plant height is inuenced by both genotype

(variety) and growing conditions. Generally, variation inheight is due more to diferences in internode length thaninternode number.

When stem elongation begins, the rst node o the stemis swollen, becomes visible as it appears above the soil sur-ace, and is commonly called jointing (Feekes 6; Zadoks31). Above this node is the immature head, which is beingpushed upward as internodes elongate to eventually emerge(heading stage). Usually a plant has about ve to six leaves onthe main shoot when jointing begins. Te immature headcontinues to develop and enlarge during stem elongationuntil it becomes complete at the boot stage. As previouslynoted, the jointing stage will not occur prior to the onset o

cold weather, as vernalization is required in winter wheat toinitiate reproductive development. When the growing pointmoves above the soil surace and is no longer protected bythe soil, the head becomes more susceptible to damage(mechanical, reeze, pests).

During stem elongation, the lower our nodes remain inthe crown. Te th node may remain in the crown or beelevated slightly. Nodes six, seven, and possible additionalnodes are elevated above the soil. When stem elongationis complete, most wheat varieties usually have three nodes

visible above the soil surace, but occasionally a ourth nodecan be ound. Te stem elongation stage is complete whenthe last lea, commonly called the ag lea, emerges rom

the whorl (Feekes 8-9, Zadoks 37-39). On most varieties,the ag lea begins to emerge just ater the third aboveg-round node is observed (or can be elt). o conrm thatthe lea emerging is the ag lea, split the lea sheath abovethe highest node. I the head and no additional leaves areound inside, the emerging lea is the ag lea. Te ag leastage is signicant because the ag lea produces a largeproportion (estimates o at least 75%) o the photosynthate(carbohydrates) or lling grain. It must be protected romdiseases, insects, and deoliation in order or the plant todevelop its ull yield potential. Flag lea emergence is a visualindicator that the plant will soon be in the boot stage.

BootTe boot stage (Feekes 10, Zadoks 45) occurs shortly ater

ag lea emergence and indicates that the head is about toemerge. Te ag lea sheath (the tubular portion o the leathat extends below the lea blade and encloses the stem) andthe peduncle (the internode which supports the head) elon-gate and the developing head is pushed up through the aglea sheath. As the developing head beings to swell insidethe lea sheath, the lea sheath visually obtains a swollenappearance to orm a boot. Te boot stage is rather short


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and ends when the awns (or the heads in awnless varieties)are rst visible at the ag lea collar (junction o the leablade and lea sheath) and the lea sheath is orced openby the head.

Heading/Flowering (Anthesis)By the time heading occurs, the development o all shoots

(main stem and tillers) on the same plant is in synchroniza-tion even though there were large diferences as to when theinitiation o the various shoots occurred (i.e. tiller initiationoccurs later than the main stem). However, throughout thepre-heading period, diferences also occur in the durationo the various developmental phases among the shoots(i.e. developmental phases or tillers are shortened), whichserves to synchronize tiller development with the mainstem so that tiller head emergence and owering occurssoon ater the main stem has headed and owered.

Te heading stage begins when the tip o the spike (head)can be seen emerging rom the ag lea sheath (Feekes 10.1;Zadoks 50), and emergence continues until the head is com-

pletely emerged (Feekes 10.5; Zadoks 58). Te heading datein most wheat varieties is determined by temperature (ac-cumulation o heat units). In some varieties, a combinationo heat accumulation and day length determines headingdate.

Shortly ater the wheat head has ully emerged, owering(anthesis) occurs. However, owering and pollination incereals may occur either beore or ater head emergence,depending on plant species and variety. Tus, cereals areclassiied as either open-lowering or closed-loweringtypes. Flowering occurs in open-owering types shortlyater head emergence. Most varieties o wheat are o the

Photo 2-3. Many wheat varieties have awns and are called beardedwheat, while other varieties are awnless.

Photo 2-4. Flowering usually begins at the middle o the head and thenprogresses upward and downward simultaneously.

open-owering type. Generally, owering in wheat beginswithin three or our days ater head emergence. Openowering is characterized by extrusion o the anther (re-productive portion o the ower which produces pollen)rom each oret on the head. In contrast, closed-oweringtypes o varieties or cereals (i.e. barley) ower prior to heademergence and the anthers remain inside each oret.

Flowering and pollination o wheat normally begins in

the center o the head and progresses to the top and bottomo the head. Pollination is normally very quick, lasting onlyabout three to ve days. Pollination occurs slightly lateron tillers than on the main stem, but all heads on a plantpollinate within a ew days o each other. Wheat is largelysel-pollinated, and pollination and ertilization has alreadyoccurred beore the pollen-bearing anthers are extrudedrom the orets. Kernels per head are determined by thenumber o owers that are pollinated. Pollen ormation andpollination are very sensitive to environmental conditions.High temperatures and drought stress during heading andowering can reduce pollen viability and thus reduce kernelnumbers.

Flowering is the transition between two broadly catego-rized growth stages in wheat. In the rst stage, vegetativegrowth, reproductive initiation, and reproductive develop-ment occur and determine the nal yield potential o thecrop and also provide the photosynthetic actory necessaryor maximum yield. Te second stage is the grain-llingperiod in which the potential yield created in the rst stageis realized. Te extent to which the potential yield is real-ized will depend on the environment and on managementinputs prior to and ater anthesis.


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Grain Filling/RipeningGrain lling ollows anthesis and reers to the period

during which the kernel matures or ripens. Within a ewhours o pollination, the embryo (rudimentary, undevel-oped plant in a seed) and endosperm (area o starch and

protein storage in the seed) begin to orm and photosyn-thates (products o photosynthesis) are transported to thedeveloping grain rom leaves (primarily the ag lea). Inaddition, starches, proteins, and other compounds previ-ously produced and stored in leaves, stems, and roots arealso transerred to the developing grain. Te grain llingperiod is critical or producing high yields because kernelsize and weight are determined during this stage. Yieldswill be reduced by any stress (high temperatures, low soilmoisture, nutrient deciencies, and diseases) occurringduring grain ll. Environmental actors afect the rate andduration o the grain lling period. Te longer this llingperiod lasts, the greater is the probability or higher yields.I this period is shortened, yields will usually be lower. InKentucky, the average length o the grain lling period isone month. Te grain ll period can be as ew as 25 daysor less in high stress environments (hot and dry weather,heavy disease, and nutrient deciencies) and may exceed35 days in high yield, low stress environments (disease-ree,high soil moisture, and moderate/cooler temperatures).

Te grain development stages are listed in able 2-1(Feekes 10.54 to 11.4; Zadoks 70 to 92). A brie descriptionand comments o the grain lling and ripening stages ol-lows below.

Watery ripe stage. Kernel length and width are establishedduring this stage. Te kernel rapidly increases in size butdoes not accumulate much dry matter. A clear uid can besqueezed rom the developing kernel.

Milk stage. During this stage there is a noticeable increasein solids o the liquid endosperm as nutrients in the plantare redistributed to the developing kernels. During themilk stage a white, milk-like uid can be squeezed romthe kernel when crushed between ngers. By the end othe milk stage, the embryo is ully ormed.

Soft dough stage. Te kernels are sot but dry. Te waterconcentration o the kernel has decreased so that the ma-

terial squeezed out o the kernel is no longer a liquid buthas the consistency o meal or dough. Te kernel rapidlyaccumulates starch and nutrients and by the end o thisstage the green color begins to ade. Most o the kernel dryweight is accumulated in this stage.

Hard dough stage. Te kernel has become rm and hardand is dicult to crush between ngers. It can be dentedwith a thumbnail. Kernel moisture content decreases roma level o 40 percent to 30 percent. At the end o the hard

dough stage (Feekes 11.3; Zadoks 87-91), the kernel reachesits maximum dry weight and the wheat is said to be physi-ologically mature (no more weight is added to the grain).Physiological maturity oten corresponds to kernel mois-ture content between 30 and 40 percent. Previous wheatswathing research at the University o Kentucky at variouskernel moisture contents indicated physiological maturityoccurred at a kernel moisture content o 38 to 42 percent(with no reduction in yield or test weight i cut at this stage).Harvesting can occur anytime ater physiological maturitybut oten does not occur because o high kernel moisture.

Ripening stage. Kernel moisture content is still high, usuallyranging rom 25 to 35 percent, when wheat begins to ripenbut decreases rapidly with good weather. Te plant turnsto a straw color and the kernel becomes very hard. Tekernel becomes dicult to divide with a thumbnail, can-not be crushed between ngernails, and can no longer bedented by a thumbnail. Harvest can begin when the grainhas reached a suitable moisture level (usually less than 20%).Oten harvest does not occur until grain moisture contentis close to 15 percent, unless drying acilities are available.

It is important or grain quality that the harvest begins assoon as possible. est weight (and hence grain yield) may bereduced during the ripening process. Decreased test weightresults rom the alternate wetting (rains or heavy dews)and drying o the grain ater the wheat has physiologicallymatured.

Wheat yield componentsCritical yield components include tiller and head number,

head size, kernel number per head and kernel size. able 2-2

highlights the key growth stages that afect yield determina-tion. For maximum wheat yields, proper management andavorable weather are necessary during these key growthstages. Te nal yield o a wheat crop is a unction o the

yield components in the ollowing ormula:

number o heads/acrex number o seeds/headx weight/seed

= grain yield/acre

Table 2-2. Key growth stages in Wheat or Yield Determination.

Critical YieldComponent Determined by:

Tiller and head number Jointing (Feekes 6, Zadoks 31)

Head Size Mid to late tillering (Feekes 3; Zadoks 23 to

29)Kernel number per head Jointing (Feekes 6; Zadoks 31)

Kernel Size Beginning at ag lea (Feekes 8; Zadoks 37)and continuing through grain ll


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1 3c u l t u r a l p r a c t I c e s

Section 3

Cultural PracticesChad Lee, James Herbek, David Van Sanford, and William Bruening

Photo 3-1. Wheat variety trials are conducted across the state to comparerelative perormances o varieties. Each variety is planted mulitiple timesat each location to minimize eld variability and to better predict per or-mance potential.

Wheat grows best on well-drained soils. Since wheatdoes not tolerate waterlogged conditions well, yields

and stands are reduced in elds prone to standing water,ooding, or poor drainage. Wheat can be grown success-ully on moderately and somewhat poorly drained soils,but the long-term yields are usually reduced by ve to tenbushels per acre due to stress placed on the wheat duringwet springs, increased winterkill, higher nitrogen losses, andinability to access elds with application equipment. Dur-ing springs with normal or below normal rainall, yields onpoorly drained soils approach those on well-drained soils.

Crop RotationMost o the wheat in Kentucky harvested or grain is

grown in a cropping system o three crops in two years(corn/wheat/double-crop soybeans). Wheat ollowingsoybean generally yields more than wheat ollowing corn(Figure 3-1). However, when wheat yields are high, the previ-ous crop has less inuence on wheat yield. Wheat is suitedto the corn/wheat/double-crop soybean rotation systemand ofers both economic and agronomic advantages. Yieldso all three crops in the rotation are increased over growing

any crop without rotation.Wheat is planted in the all ater summer annual crops are

harvested and can be harvested early enough in the summeror a second crop to be planted (double-cropped). Double-cropping is an important economic component o the wheatenterprise in Kentucky. More than 85 percent o the harvestedwheat acreage is double-cropped, primarily with soybeans.

Variety SelectionChoosing a wheat variety is one o the most important

management decisions that Kentucky wheat producersmake. Yield potential is clearly important, but the deci-sion is complicated by such actors as the need or diseaseresistance; the double-cropping system, which requiresearly maturity; the extreme year to year climatic varia-


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1 4 c u l t u r a l p r a c t I c e s

tion in Kentucky, and the need tospread out the harvest maturitydate so every variety is not ready toharvest at once. It makes sense tominimize risks by planting several

varieties with good yield and testweight potential that complementone another in terms o disease re-sistance, maturity, and resistanceto spring reeze damage.

Proper use o variety test per-ormance data is the rst step inmaking this important decision.Te University o Kentucky SmallGrain Variety Perormance estsprovide the most comprehensivesource o inormation on varietiestested under a broad range o environments. Results o the

variety tests are published annually and are available atCooperative Extension Service oces and online at www.uky.edu/ag/WheatVarietyest. Te best use o Universityo Kentucky variety perormance data or variety selectioncan be achieved by applying the ollowing basic principles.

Conventional vs. No-till TestingBased on 10 years o conventional vs. no-till data rom

the University o Kentucky variety testing program, varietyperormance can be assessed independently o the tillagesystem used. Tis act enables growers to identiy superior

varieties based on perormance regardless o the tillage

system used.

Multi-year/Multi-location DataWhile many growers ask about the variety that looked

best in this years test, it is more useul to know whichvarieties have perormed well over a range o conditions.When interpreting the results in the variety perormancereport, it is important to note that variety yield is relative.Tis means that comparisons among varieties should onlybe made among those varieties in the same test or withinthe same analysis averaged across locations. Te state sum-mary table provides perormance data averaged across testlocations and years. It provides the best estimate o varietalperormance, particularly the 2 and 3 year averages. Whenselecting varieties, growers should rst utilize data romthe state summary table. Once several candidate variet-ies have been selected, the grower should examine theirperormance in the closest regional test. Ater identiyinga group o varieties with high grain yield potential, varietalselection can be based on secondary characteristics suchas test weight, disease resistance, lodging, height, maturityand straw yield potential.

Figure 3-1. Wheat iscommonly grown ollowingcorn in Kentucky. As overallwheat yield potentialincreases, the previous crophas less eect on wheatyield. (1998 through 2008at Lexington, Kentucky, dataprovided by John Grove)

40

40.0

60.0

80.0

100.0

120.0

60

y = 0.8484x + 17.239

R2

= 0.9203

y = 1.1516x - 17.239

R2 = 0.9551

80

Average Wheat Yield (bu/acre)

WheatGrainYie

ld(bu/acre)

100 120

Wheat after corn

Wheat after soybean

Photo 3-2. While most wheat in Kentucky is grown or grain, some isgrown or orages. The University o Kentucky tests wheat varieties orperormance both in orage yields and grain yields.

Wheat varieties that have perormed well under diverseconditions are likely to perorm well again. For growerswho want to try a new variety, it is best to choose onethat has been evaluated or at least one year. I a varietyhas been tested or one year only, it is best to use the statesummary table, rather than using single year data rom asingle (regional) test. Depending on a growers location, ad-ditional variety perormance data may be useul rom other(bordering) state variety testing programs. Te Universityo Kentucky Small Grain Variety esting Program websitehas links to these programs.

Economic Analysis o VarietiesFarmers are always interested in high yields, but the

highest yielding variety may not always be the most prot-able. One needs to consider other economic actors suchas disease susceptibility (may require ungicides), lodging


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Table 3-1. Recommended number o wheat seeds toplant per square oot or per drill-row oot.

RowWidth

(in)

Row LengthNeeded or1 sq t (in)

Seeds/sq t

30 35

Seeds/row t Neededa

4 36.0 10 126 24.0 15 18

7 20.6 17 20

7.5 19.2 19 22

8 18.0 20 23

10 14.4 25 29a I planting time is delayed, increase seeding rates by two to

three seeds/sq t (one to two seeds/row oot) or every two-week delay beyond the optimum planting date.

Table 3-2. Number o pounds owheat seed needed, depending onseed size and seeding rate.

Seeds/lb

Seeds/sq ta

30 35

lbs/acre10,000 131 152

12,000 109 127

14,000 93 109

16,000 82 95

18,000 73 85

20,000 65 76a Based on 90 percent or greater germina-

tion.

(costs more to harvest), late maturity(delays soybean planting), potentialstraw yield as a secondary commodity,low test weight (discounts at the eleva-tor) and seed cost. All o these actors

require study and evaluation to de-termine the most protable varietiesor a particular operation. Maximumproductivity and protability beginwith careul variety selection. Once

varieties have been selected, the bestguarantee o obtaining the qualityseed necessary or the highest yields isto use certied seed or seed o provenhigh quality rom an established, repu-table dealer.

Planting PracticesTe target population or planting wheat is a uniorm

stand o 25 plants per square oot (225 plants per squareyard) (able 3-1). Usually planting 30 to 35 seeds per squareoot (1,524,600 seeds/A) will result in the desired plantpopulation. Planting methods include seedbed preparationor no-tillage planting (see Section 4Planting Methods),planting date, seed placement, seeding rate, row width, anduse o tramlines.

Planting Date. Te recommended planting date or most oKentucky is October 10 through October 30. Tis windowis a compromise between early planting to ensure adequateall growth and winter survival and later planting to de-crease disease and insect inestations. ypically, these dateswill all within a period o one week beore to one week aterthe expected date o the rst all rost. Soil temperaturesare usually high enough during this window or the crop toemerge in seven to ten days or less. Also, the length o timebetween the rst rost and winter dormancy or growth iscritical or the development o an adequate number o tillers.illers developed in the all are essential to producing high

yields. A longer period o growth in the spring and moreextensive root systems mean that all tillers account ormost o the grain produced in an intensively managed crop.

Late-planted wheat misses much o the critical all grow-

ing period, generally sufers more winter damage, is moreprone to heaving (upliting o the plant and root system dueto alternate reezing and thawing o soil), tillers less, hasreduced yields, and matures later than wheat planted at therecommended time. It is dicult, i not impossible, to makeup or late planting by management practices employed atlater growth stages.

Planting too early, on the other hand, can result in excessiveall growth and create the potential or more winter injury(growth stages too advanced), greater risk o spring reezeinjury, all disease inection, and increased problems withaphids (which vector barley yellow dwar) and Hessian y

inestations. Delaying planting until October 10 in northernKentucky and October 15 in southern Kentucky generally

averts Hessian y damage. Tese dates are known as the y-ree planting dates. Te Hessian y-ree date is based partlyon the rst all reeze date, so i air temperatures are warmerin the all, the efective y-ree date would actually be delayedthat season.

Seed Placement. Plant seeds 1 to 1 inches deep when soilmoisture levels are adequate, slightly deeper i moistureis decient. Do not plant wheat seed more than 2 inchesdeep. Rapid emergence and good root development startwith good seed-soil contact.

Many wheat varieties have small seed, and when seed isplanted deeper than 2 inches, emergence is delayed. Some

semi-dwar varieties with short coleoptiles might open therst lea below ground and die. Deep seed placement delaysemergence and reduces stand, resulting in plants with less

vigor, less initial vegetative growth, and reduced til lering.Te other problem is not planting seed deep enough.

Planting seed less than -inch deep can result in unevengermination and emergence because o dry soil. Shallowseed placement also can result in more winter injury andgreater susceptibility to heaving. I seed is planted shallowand timely rains accompany planting, then adequate standscan be achieved.

Seed placement is especially critical or no-till planting.Seed must be placed in the soil at the proper depth andbelow all the plant residue or mulch. Te mulch shouldbe distributed evenly on the soil surace to help drills suc-cessully slice through the mulch and place the seed in thesoil. Poor seed placement is a major problem in no-tillageplanting. Fast, uniorm seedling emergence provides quickground cover and erosion protection.

Seeding Rate. Wheat seed size varies dramatically amongvarieties and can be inuenced by production environmentand degree o conditioning. Using seeding rates expressedin terms o volume or weight (bushels or pounds) per acre


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Photo 3-3. Seeding wheat rows at a diagonal to the old corn rows is

generally a good practice in no-till elds.

Photo 3-4. Corn residue that piles in the eld can prevent the drill rom

placing the wheat seed under the soil surace. Seeds either ail to germi-nate or seedlings are killed during winter, leaving blank spaces in the eld.

without consideration o seed sizecan result in stands thatare too low or too high. Proper stand establishment requiresthat the seeding rate be determined in terms o number oseeds per unit area (per square oot or linear row oot). Seed-ing rates below optimum may reduce yield potential, whileexcessive seeding rates increase lodging, create a greaterpotential or disease, and increase seed costs. Te optimumplanting rate is 35 seeds per square oot (1,524,600 seeds/A)with an objective o obtaining at least 25 plants per square

oot. Te seed rate and seed size should be determined to cal-culate how many pounds o seed per acre are needed. Seedsizes and the pounds needed can vary widely (able 3-2).

For precise seeding, calibrate your planting equipment.Seeding rate charts on drills may not be precise and sizeand shape o seed can afect seed delivery. (See Section4Planting Methods or a ve-step procedure or propergrain-drill calibration.)

Row Width. Te most practical wheat row widths are nor-mally 7 to 8 inches, combining the higher yield potential onarrow rows with the efective movement o planting equip-ment through the eld. Research throughout the growing

region o sot red winter wheat has shown 5 percent to 10percent higher yields when wheat is planted in 4-inch rowsversus 8-inch rows. Likewise, research has shown signicant yield decreases or wheat grown in row spacings greaterthan 10 inches. Wheat must be planted at a uniorm rateand depth, and conservation requirements must be met.

Drills with units 4 inches apart are likely to clog due toexcessive surace residue or clods. ypically, drills withunits about 7 to 8 inches apart have minimal clogging, butrelatively high yield potential. Some armers are choosingto use modied planters with units spaced 15 inches apart.

Tese planters are normally used in soybean and corn. Tecost o modiying the equipment is less than purchasing adrill, but the yield loss associated with the wider row spac-ings may not justiy 15-inch rows.

Based on limited research in Kentucky, wheat in 15-inchrows will yield about 15 percent to 20 percent less thanwheat planted in 7.5-inch rows. For wheat normally yielding70 bushels per acre, that is a yield loss o 10.5 bushels peracre, or $63 per acre or wheat being sold at $6.00 per bushel.

Based on these numbers, not very many acres are neededbeore a drill becomes more economical than a planter.

Tramlines and/or GPS. ramlines are roadways placed in thewheat eld at planting and used by equipment or applyingpesticides and ertilizers. ramlines should match the widtho the applicator tires and be spaced to match the width othe applicator boom. ramlines allow timely applicationo input and more uniorm applications o nutrients andpesticides with no skips or overlaps.

ramlines can be ormed by blocking drill spouts and notplanting wheat seed in specic rows. ramlines can also beormed by planting wheat in all rows and then running over

the same tracks each time an application is made. ramlinesormed by blocking seeding spouts will a llow wheat plantsin rows beside the tramlines to compensate some or theunplanted area. Tere is no compensation or plants thathave been run over past jointing (Feekes 6, Zadoks 31).

When blocking drill spouts, using tractors with nar-row tires so only one drill row needs to be blocked is arecommended practice. Devices that automatically closethe selected drill spouts on the appropriate planting passthrough the eld are available or most grain dril ls. Fertil-izer and spray booms should be at least 40 eet wide to be


17/72


economical. Te distance rom therst tramline to the edge o the eldshould be one-hal the width o thesprayer.

When running over wheat to orm

tramlines, use the same track or eachapplication and do the rst track (ap-plication) prior to jointing (Feekes 6,Zadoks 31) to allow plants in adjacentrows to compensate or the tramlines.Lightbars enabled with GPS (globalpositioning system) receivers can be

very useul in helping to establishtramlines. Lightbars limit the amounto overlap and skips or nutrient andpesticide applications.

Winterkill and Freeze InjuryWheat is subjected to adverse weather conditions during

much o its growth period. Autumn rosts and cool tem-peratures actually help by hardening plants or the monthso cold winter weather ahead.

Expect winterkill on poorly drained soils, with extremetemperature uctuations, where poor all root develop-ment occurred, and with sustained low temperatures(particularly with no snow cover). Extremely cold winterstend to cause more winterkill in varieties developed inmore southerly locations because they have less winterhardiness. Heaving is a major cause o late winter or earlyspring damage to small plants due to extreme temperature

uctuations, especially on poorly drained soils.Wheat seeded close to the recommended dates typicallywill receive little damage rom a spring reeze. Spring reezeinjury can occur when low temperatures coincide with

Photo 3-5. Wheat heads that are bleached whiteare a clear indication that heads were killed by areeze event.

Photo 3-6. Wheat is regrowing ater a reezeevent. Normally, development o this regrowthwill be delayed, pushing harvest to later in theseason.

sensitive plant growth stages (able 3-3). Te risk o spring

reeze injury is greater when conditions cause wheat tobreak winter dormancy (greenup) and begin growing andthose conditions are ollowed by reezing temperatures.Tese scenarios occur with unusually warm temperaturesin February or March or rom unusually late reeze events inApril or May. Injury can occur across large areas o the eldbut usually is most severe in low areas or depressions in theeld where cold air settles. A late spring reeze can reduce

yield because o damage to the head and stem. Usually, aweek to ten days o good warm temperatures and adequatesunlight are required beore head and stem damage roma reeze event becomes visible. I cool, cloudy days persist,then more time may be needed to assess the damage. I the

plants are damaged rom the reeze, then the wheat stemswill likely be damaged close to the ground. Heavy rainallwill knock over the damaged wheat and severely reduce

yields.

Table 3-3. Freeze injury in wheat.a

GrowthStage Feekes Zadoks

Approx.Injurious

Temp. (2 hrs) Primary Symptoms Yield Eect

Tilleringb 1-5 20-29 12F Lea chlorosis; burning o lea tips; silage odor; blue cast to elds Slight to moderate

Jointing 6-7 31-32 24F Death o growing point; lea yellowing or burning; lesions, splitting, orbending o lower stem; odor

Moderate to severe

Boot 10 41-49 28F Floret sterility; spike trapped in boot; damage to lower stem; lea discoloration; odor

Moderate to severe

Heading 10.1-.5 50-58 30F Floret sterility; white awns or white spikes; damage to lower stem; lea discoloration

Severe

Flowering 10.51-.54 60-71 30F Floret sterility; white awns or white spikes; damage to lower stem; lea discoloration

Severe

Milk 11.1 75 28F White awns or white spikes; damage to lower stems; lea discoloration;shrunken, roughened, or discolored kernels

Moderate to severe

Dough 11.2 85 28F Shriveled, discolored kernels; poor germination Slight to moderatea Inormation in this table assumes timely rainall events occurring ater the reeze event.b See Section 2 or more inormation about growth stages.


18/72


o check or damage to an un-emerged wheat head, cut into the stemto nd the growing point (developinghead). An undamaged head normallyappears light green, glossy, and turgid.

A killed head is pale white or tan,limp, shrunken, and not developingin size. Spikelets within a single headcan be damaged as well. Growing tis-sue o plants that have been rozen isdry, bleached, and shrunken. See theSupplementsection or more pictureso reeze damage.

he temperatures and growthstages listed in able 3-3 work well inmost situations as a general guideline;however adequate yields may still beproduced.

Tere is some evidence that timing onitrogen ertilizer application in relation to the reeze eventmay help reduce the damage rom a reeze event. Te theoryis that or a short period o time, as wheat takes up nitrogenthe concentration o nitrogen in the plant cell will be highenough to act as a kind o anti-reeze agent. Te problem isthat there is no sound recommendation or applying nitrogento help with this.

In addition, some wheat varieties may be a little moretolerant to spring reezes based on the mechanisms thatdetermine owering in wheat. Flowering in some wheat

varieties seems to be controlled more by day length whileowering in others may be controlled more by temperature.

Unusually warm temperatures could accelerate crop devel-opment in varieties more responsive to temperature moreso than in varieties more responsive to day length. In thesecases, varieties more sensitive to temperature would be at agreater risk or spring reeze. Assessing wheat damage roma reeze event can be dicult. In addi-tion to evaluating the stems and headsor reeze damage, one also must lookat extended orecasts. I rain is not inthe orecast, armers may be less likelyto destroy a damaged wheat crop.

Determining Plant Populations,Tiller, and Head CountsPlant Populations. Ater the wheathas emerged, make a stand count todetermine i your target populationwas achieved and i the nal stand isacceptable or maximum yield poten-tial. Make all stand counts one to twoweeks ater emergence. Make springstand counts beore greenup o the

Table 3-4. Wheat yield potential based on plants persquare oot.

FinalStand

(%)

Plants per:Potential

Yielda(%)sq t sq yd

100 30 - 35 270 - 315 100

80 24 - 28 216 - 252 10060 18 - 21 162 - 189 90 - 95

50 15 - 18 135 - 162 75 - 80

40 12 - 14 108 - 126 60 - 70

20 6 - 7 54 - 63 40 - 50a This provides an estimate o the relationship o wheat stand to

yield potential and is only a guide. Many actors (plant vigor,weather, disease, ertility management, planting date, andvariety) inuence how a wheat stand ultimately responds toachieve its nal yield potential.

Table 3-5. Length o row needed or1 sq t.

RowWidth

(in)

Row Lengthor 1 sq t

(t) (in)6 2.0 24.07 1.7 20.6

7.5 1.6 19.28 1.5 18.0

10 1.2 14.415 0.8 9.6

Photo 3-7. Using a hand lens or micro-scope to examine the growing point owheat can help determine i the cropsurvived a reeze event.

Photo 3-8. A dowel road with specic lengths marked onit can be used to count plants and tillers on a square-oot-basis.

plants occurs to determine i winter damage has reducedthe initial plant population obtained in the all. Count onlywhole plants, not tillers. Fields with stand counts below15 plants per square oot have less than 75 percent yieldpotential (able 3-4) and probably should not be kept butused instead or planting corn or soybeans. I stand countsare adequate to keep but somewhat reduced rom optimum,consider an early nitrogen application.

To determine the number o plants per square oot: Useayardstick,orcutadowelrodtoa3-footlength. Place themeasuring sticknext toan average-looking

row, and count all plants in the 3-oot length o the row.Record the number.

Repeatthecountingprocessinatleastveotherlocationswell spaced around the eld. Record all numbers.

Averageallofthestandcountsfromtheeld.


19/72


Calculateplantspersquarefootwiththefollowingequation:

plant number =(average plant count 4)/row width in inches

A second method to counting stands is to determine the lengtho row needed to equal one square oot (able 3-5). Markthe needed length on a dowel rod or stick and then countthe plants in a row.

A third method is to count the plants, or til lers in 1, 2 or 3 eeto row and use able 3-6 to determine stands.

Tiller and Head Counts. aking a tiller count which includesmain shoot and tillers at Feekes 3 (roughly Zadoks 22through 26) is the rst step in all elds or determiningnitrogen needs in late winter or early spring. o determinetiller numbers, count all stems with three or more leaves.iller counts below 70 per square oot indicate the need ornitrogen at Feekes 3. At recommended populations, manyplants will have only three to our stems (main shoot plus twoto three til lers, Zadoks 22 or 23). Tus, 70 to 100-plus tillers

(stems) per square oot at Feekes 3 are considered adequate.Head counts can be taken late in the season ater headshave ully emerged (Feekes 10.5, Zadoks 58 or later) to helpestimate yield potential. An ideal count or maximum yieldsis 60 to 70 heads per square oot (540 to 630 per square yard)with 35 kernels per head and 16 to 18 spikelets per head. Foradequate yields, 55 heads per square oot (500 per square

yard) are needed. I the number o heads per square oot istoo high (90 to 100), severe lodging can occur and seedingrates were probably too high. Use the same procedure tocount tillers or heads as outlined above or plant populations.

Table 3-6. Wheat stand count table.

RowWidth

(in)

RowLength

(t)Area

(sq t)

Plants (or tillers) per counted area

10 15 20 25 30 40 60 80 100 120 140 160

Plants (or tillers) per sq t

7 1 0.58 17 26 34 43 51 69 103 137 . . . .

2 1.17 9 13 17 21 26 34 51 69 86 103 120 1373 1.75 6 9 11 14 17 23 34 46 57 69 80 91

7.5 1 0.63 16 24 32 40 48 64 96 128 . . . .

2 1.25 8 12 16 20 24 32 48 64 80 96 112 128

3 1.88 5 8 11 13 16 21 32 43 53 64 75 85

8 1 0.67 15 23 30 38 45 60 90 120 . . . .

2 1.33 8 11 15 19 23 30 45 60 75 90 105 120

3 2.00 5 8 10 13 15 20 30 40 50 60 70 80

10 1 0.83 12 18 24 30 36 48 72 96 120 . . .

2 1.67 6 9 12 15 18 24 36 48 60 72 84 96

3 2.50 4 6 8 10 12 16 24 32 40 48 56 64

15 1 1.25 8 12 16 20 24 32 48 64 80 96 112 128

2 2.50 4 6 8 10 12 16 24 32 40 48 56 64

3 3.75 3 4 5 7 8 11 16 21 27 32 37 43

Lodging Control and Plant Growth RegulatorsLodging can be a problem when too much ertilizer

nitrogen is used, too thick o a stand is established and/or growing conditions avor excessive growth. Lodgedwheat can result in decreased combine speed because othe amount o straw that must be processed through thecombine, decreased grain recovery, delayed harvestingater rainall and heavy dew, and more dicult planting

conditions or double-crop soybeans that ollow wheat.Risk o wheat lodging can be reduced by choosing good

varieties, establishing the correct stand and using therecommended amount o ertilizer nitrogen. Situationsdo occur, however, in which there is a large carryover oresidual soil nitrogen or weather conditions produce verylush crops and the potential or lodging is high.

When the potential or lodging is high, consider using thegrowth regulator such as Cerone. Cerone prevents lodgingby shortening the wheat plant and strengthening the straw. Itdoes not increase yields i no lodging occurs. Correct applica-tion is critical and should be made between Feekes 8 and 10

(Zadoks 37 and 45). Never apply Cerone to crops with exposedheads. Research at the University o Kentucky showed bestresults when Cerone was applied at Feekes 8 or 9 (Zadoks 37or 39). Careully read the label, and ollow all directions.


20/72

2 0 p l a n t I n G a n D D r I l l c a l I b r a t I o n

Section 4

Planting and Drill CalibrationJames Herbek and Lloyd Murdock

The objective when planting wheat is to establish a uniormstand o at least 25 plants per square oot with adequate

all growth or tiller development and an established rootsystem or winter survival. Planting methods include drilling,broadcast seeding, and aerial seeding. Each has advantagesand disadvantages. A planting method should be based onplanting equipment, time and labor availability, seeding costs,planting date opportunity, weather, crop usage, yield goals,and stand establishment risks associated with each method.In addition, calibration o planting equipment is critical togetting the correct number o seeds in the soil. Methods or

drill calibration are included at the end o this section.As machinery moves across a eld, soil compaction is

a concern. Compaction causes the soil to waterlog easily,reduces air movement through the soil, puts the wheatcrop under stress, and can reduce the yield. Fields shouldbe tested or compaction by using a penetrometer or similardevice when there is ample water in the soil. I soil compac-tion exists in the eld, it should be alleviated beore wheatis seeded, when the eld is relatively dry. Subsoiling equip-ment can alleviate deep compaction while a eld cultivatorcan alleviate shallow compaction. Tese tillage operations

should only be conducted when the eld is dry. I the eldis wet, then these operations could actually worsen com-paction. Some types o subsoilers leave most o the residueon the surace and other types cause considerable soildisturbance which would require additional tillage. Oncethe compaction is remedied and is the eld is managed ina complete no-tillage system, the eld usually will remainree o compaction.

Drilling

Te best results in wheat stand establishment and yieldare obtained by seeding with a grain drill. A drill ensuresgood seed-to-soil contact, promotes rapid germination,results in more uniorm and optimum stands, reduceswinter injury, and increases yields over broadcast seedingand aerial seeding. (For calibration o a drill, see the end othis section.)

Photo 4-1. Proper seeding techniques are critical or an excellent stando wheat.


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2 1p l a n t I n G a n D D r I l l c a l I b r a t I o n

drill unit is not continually in a row o corn stalks.Winterkill is a problem about every our or ve years in

Kentucky. It can be more pronounced in no-til l plantings ithe planting depth is inch or less. o remove this increasedrisk, use the proper planting methods and adjustments toplant 1 to 1 inches deep. Also, be sure to plant a winter

hardy variety.Drills should be adjusted to target 30 to 35 live seeds per

square oot or conventional tillage systems and 35 to 40live seeds per square oot or no-tillage systems.

BroadcastingWheat seed can be broadcast as either a planned or emer-

gency seeding method. Te wheat seed is broadcast on thesoil surace with a ertilizer spreader and incorporated intothe soil with light tillage (usually disk or eld cultivator).Broadcasting is a ast method o seeding wheat and is anacceptable option i corn or soybean harvest is delayed or

weather delays push planting dates to the end o or beyondthe optimum planting period.

When broadcast seeding into corn stubble, til lage is otenconducted beore broadcasting. Once broadcasting occurs,then a light tillage operation incorporates the seed intothe soil. When broadcasting wheat into a eld o soybeanstubble, generally a light tillage operation ater broadcastingis necessary.

Broadcast seeding oten results in uneven seed place-ment in the soil, which results in uneven emergence andstands. Seeds may be placed as deep as 3 to 4 inches, where

Drills can be used or conventionaltillage, reduced tillage, and no-tillageield conditions. Conventional/ulltillage provides a level, smooth seed-bed or drilling and results in a more

uniorm planting depth. Drills withadditional coulters and more downpressure on the planter units canestablish a good stand o wheat inreduced tillage and no-tillage elds.Leaving crop residue on the soilsurace protects the soil rom ero-sion until the wheat crop becomesestablished. About hal o the wheatcrop in Kentucky is currently plantedinto no-till conditions with a dril l. Forelds that still receive tillage, disking isprobably the most common method.

No-tillage conditions provide sev-eral advantages over tillage condi-tions, including reduced soil erosion,reduced equipment requirements,reduced labor costs and reduced uelcosts. No-tillage conditions also al-low more timely management, suchas spring applications o nitrogen (N) ertilizer. On theother hand, no-till wheat can result in variable plantingdepths and uneven stands, especially i equipment is notproperly adjusted or no-tillage elds. In the early stages ono-tillage adoption by a producer, yields can be a reducedin a high-yield environment. However, management ex-

perience seems to eliminate most o these disadvantages.Yield comparisons rom many research and on-arm trialsover the last 25 years show little or no diference in yieldbetween no-tillage and til lage. Te small increase in yieldso soybean and corn in a true no-tillage system or wheat,double-cropped soybean and corn is attractive to produc-ers, also.

Residue management varies with the previous crop.Planting into no-tillage conditions ater soybeans is idealbut may not be the most economical crop rotation. Plant-ing into corn residue requires proper management o thatresidue in order to get uniorm seed depth and uniormemergence. Combines should have residue choppers andspreaders to distribute the corn residue evenly. In manyelds, wheat seeding occurs very soon ater corn harvest.Normally, stalk shredding or mowing prior to seeding isnot necessary i cornstalks are moist and rmly in the soil.However, i two or three weeks will elapse between stalkshredding and wheat seeding, then shredding the cornresidue can improve drill coulter penetration. A rotarymower may have a tendency to windrow the residue. Aail mower is a better tool and distributes the residue moreevenly or a more uniorm seeding depth. Drilling wheatat an angle to the corn stalk row is also helpul because a

Photo 4-2. Wheat can be seeded into heavy corn residue with modern no-tillage drills.


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many seeds will germinate but will not emerge throughthe soil surace. Other seeds may be placed very shallowor on the soil surace. Tese seeds oten do not survivedue to dry soil or winter damage. Te uneven stands rombroadcasting oten result in lower yields comparing with

drilling.One method o improving stand uniormity is to broad-cast seed in two passes across the eld, with a hal seedingrate or each pass. Te second pass is made perpendicularto the rst pass. While this method should improve standuniormity, it also increases time required to seed the eld.

Because plant establishment potential is reduced andseed placement is not uniorm, seeding rates should beincreased or broadcast seeding. Increase broadcast seedingrates by 30 percent to 35 percent over drilled seeding rates.Tis equates to seeding rates o 45 to 47 seeds per squareoot (or approximately 2 bushels per acre at average seedsize). Soil moisture, crop residue and accuracy o seed in-

corporation into the soil are crucial to stand establishment.Broadcasting wheat with ertilizer is a ast way to seed

ater harvest. ake precautions to ensure that the seed isuniormly blended with the ertilizer and that the ertilizer-seed mixture is uniormly applied. Seed should be mixedwith ertilizer as close to the time o application as pos-sible and applied immediately ater blending. Allowing theertilizer-seed mixture to sit ater blending (longer than eighthours), particularly with triple super phosphate (0-46-0) ordiammonium phosphate (18-46-0), results in seed damage(reduced germination) and, subsequently, a poor stand.

In summary, broadcast seeding is a aster method o seed-ing and can save time during corn or soybean harvest. Te

time saved may ofset some o the greater costs and potentialyield loss associated with broadcast wheat. Disadvantagesinclude inconsistent seed depth and emergence, nonuniormstands, potential or reduced stands, usually lower yields,increased chances o winter injury and higher seed costs.

Aerial SeedingAerial seeding is a risky method or establishing wheat

and is not very common. It may be considered as an optionwhen harvest o the summer crop is delayed well into theoptimum time or planting wheat. An airplane or helicop-ter drops a high rate o wheat seed onto the soil surace

through the canopy o an established summer crop such ascorn or soybean. Te wheat seed is not incorporated intothe soil, making successul germinate and stand establish-ment heavily dependent on adequate and timely rainall.Depending on the weather during stand establishments,

yields rom aerial seeding can be very high or the crop canbe a complete ailure.

Aerial seeding normally works best when the summercrop o corn or soybean is turning yellow and leaves aredropping to the ground. Tis lea drop can provide a mulch

cover and improve the environment or germination. Evenin the best conditions, aerial seeding will result in wheatplants with crowns at or above the soil surace, making thewheat crop extremely vulnerable to winterkill.

Historically, aerial seeding was conducting in Septem-

ber prior to the Hessian y ree date. Tis practice is notrecommended, because rainall is usually low during thisperiod, and there is a greater risk o damage rom Hessiany, aphids, take-all and wheat spindle streak mosaic virus.Aerial seeding is not recommended or late October orNovember plantings, either. Normally, wheat growth romlate aerial seedings will be inadequate or winter survival.

Seeding rates should be 50 to 55 seeds per square oot oraerial seeding, nearly 40 to 50 percent greater than thoseused or drill seeding. Expected stand establishment willbe about 50 to 75 percent o the seeding rate.

In summary, aerial seeding is a high-risk venture andshould only be considered or the early window o wheat

seeding dates when harvest o the summer crop is delayed.Even in these cases, seeding wheat late with a drill may havebetter odds o surviving than aerial-seeded wheat.

Grain Drill CalibrationSeveral methods or calibrating drills are presented

below. For any o these methods, ensure that all units areproperly delivering seed beore conducting any calibration.Look or any loose hoses or chains, gears, etc. that mightafect seed delivery.

For all target recommendations, we are expecting agermination rate o 90 percent. For example, when 30 to

35 seeds/sq t is recommended, we are expecting 27 to 32plants to emerge. Seeding rates or no-tillage are slightlyhigher than conventional tillage, because we anticipateslightly lower emergence rates.

When calibrating a drill, make note o the standard ger-mination o seed as marked on the seed tag. Tat numbercan be used with the desired live seeding rate to calculatehow many total seeds to drop. For example, i the targetedlive seeding rate is 35 live seeds per sq t and the standardgermination is 80 percent, then the total seeds needed are38 seeds per sq t (30 0.8 = 38). able 4-1 can help withcalculations o standard germination and adjusted seedingrate.

Table 4-1. Adjusted seeding rate needed based on standard germina-tion and desired live seeding rate.

Live Seeding Rate(seeds/sq t)

Standard Germination Rate

95% 90% 85% 80% 75%

Adjusted Seeding Rate (seeds/sq t)

25 26 28 29 31 33

30 32 33 35 38 40

35 37 39 41 44 47


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2 3p l a n t I n G a n D D r I l l c a l I b r a t I o n

Once desired seeding rate has beendetermined, based on eld conditionsand standard germination o the seed,then the ollowing methods can beused.

Method 1. (most accurate) A ve-stepprocess or proper grain-dril l calibra-tion ollows:

Step 1. Use able 4-2 as a guide orseeding rates at various row widthswhen the seed germination test is 90percent or higher. able 4-3 gives es-timates o the pounds o seed neededper acre at seeding rates o 30 and 35seeds per square oot or a known seedsize.

Step 2. Calculate the number o

seeds required in 50 drill-row eet.For example, with 7-inch wide rowsand on-time planting, an appropriateseeding rate would be 20 seeds perdrill-row oot multiplied by 50 eet,which equals 1,000 seeds plantedevery 50 eet o row. Count 1,000seeds o each variety and put them ina graduated tube, such as a rain gauge,or other clear tube or cylinder. Markthe level o the 1,000 seeds on the tube.Or, i you have scales, weigh the 1,000seeds o each variety.

Step 3. Hook a tractor to the graindrill so that the drive wheels o thedrill can be raised of the ground andthe drive gears can be engaged. Jack upthe drive wheel so it clears the groundand turn the wheel several revolutionsto be certain all working parts areturning reely. Check all dri ll spouts or blockages.

Step 4. Determine the number o revolutions the drivewheel must make to travel 50 eet. Measure the distancearound the drive wheel. Tis distance can be measureddirectly with a tape measure or calculated by measuringthe diameter or distance across the tire and multiplying

that distance by a actor o 3.2. For example, i the drivewheel measures 30 inches rom tread to tread (diameter),the distance around the tire should measure 96 inches (30x 3.2). Te number o tire revolutions per 50 eet (50 x 12inches) equals 600 inches. Divide 600 inches by 96 inchesto get 6.25 revolutions o the tire per 50 eet o travel. Makea mark on the wheel so the number o revolutions can beconveniently determined when the wheel is turned.

Table 4-3. Number o pounds o wheatseed needed, depending on seed sizeand seeding rate.

Seeds/lb

Seeds/sq ta

30 35

lb/acre

10,000 131 152

12,000 109 127

14,000 93 10916,000 82 95

18,000 73 85

20,000 65 76a Based on 90 percent or greater germination.

Table 4-2. Recommended number o wheat seeds toplant per 50 drill-row eet.

RowWidth

(in)

Row LengthNeeded or

1 sq t(in)

Seeds/sq t

30 35

Seeds/50 drill-row tneededa

4 36.0 500 600

6 24.0 750 900

7 20.6 850 10007.5 19.2 950 1100

8 18.0 1000 1150

10 14.4 1250 1450a Assumes 90 percent germination rate.

Photo 4-3. Drill calibration takes time, but the nal results are worth the eort.

Step 5. Calibrate the drill. Putatleastaquartofseedofthevarietytobecalibrated

over at least two drill spouts. (You get better accuracy iyou use more than one drill spout.)

Setthedrillonaratesettingexpectedtobeclosetothatdesired, and turn the wheel the number o revolutions

needed or 50 eet (as determined in step 4) while catchingthe seed rom each spout in a separate container. Pour theseed caught into the precalibrated tube (as determined instep 2), and check the level. Repeat or each o the drill spouts.

Changesettingsasneeded,andrepeatuntilyougettheappropriate number o seeds (level marked on the tube).Repeat the above steps or each variety.

Option: Te above procedure also can be used underactual eld conditions by catching seed while the drill istraveling a distance o 50 eet. Use able 4-4 to determinehow much seed should be collected rom each row unit.


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Table 4-4. Weight o seed needed or one row unit and 50 eet o row,depending on seed size, target seeding rate and spacing between rowunits (assuming 90% seed germination).

30 seeds/sq t (target seeding rate)

Seed Size(seeds/lb)

Row Width (in)

7 7.5 8 7 7.5 8

Seed collected rom one unit in 50 t o row

ounces grams

10,000 1.55 1.67 1.78 44.1 47.2 50.3

12,000 1.30 1.39 1.48 36.7 39.4 42.0

14,000 1.11 1.19 1.27 31.5 33.7 36.0

16,000 0.97 1.04 1.11 27.5 29.5 31.5

18,000 0.86 0.93 0.99 24.5 26.2 28.0

20,000 0.78 0.83 0.89 22.0 23.6 25.2


Seed Size(seeds/lb)

Row Width (in)

7 7.5 8 7 7.5 8


ounces grams

10,000 1.81 1.94 2.07 51.4 55.1 58.7

12,000 1.51 1.62 1.73 42.8 45.9 49.0

14,000 1.30 1.39 1.48 36.7 39.4 42.0

16,000 1.13 1.22 1.30 32.1 34.5 36.7

18,000 1.01 1.08 1.15 28.6 30.6 32.6

20,000 0.91 0.97 1.04 25.7 27.6 29.4


Seed Size(seeds/lb)

Row Width (in)

7 7.5 8 7 7.5 8


ounces grams

10,000 2.07 2.22 2.37 58.8 63.0 67.1

12,000 1.73 1.85 1.97 49.0 52.5 55.9

14,000 1.48 1.59 1.69 42.0 45.0 48.0

16,000 1.30 1.39 1.48 36.7 39.4 42.0

18,000 1.15 1.23 1.32 32.6 35.0 37.3

20,000 1.04 1.11 1.18 29.4 31.5 33.6Calculation to determine seeds needed:

Ounces o seed needed = [seeds per sq t x (50 t x row width in t) seeds perpound) x 16 ounces per pound]/0.9Where seeding rate is seeds per sq t, row width is in eet, and 0.9 is 90% germi-nation.

Method 2. (less accurate) Put the wheat seed in the hoppero the dril l to cover two or three drill spouts. Keep the seedtag or reerence. Pulloneormorehosesooftheplanterunitsandattach

bags to the bottom o the hoses using either zip ties or

duct tape. Withthedrillengaged,drivethedrillfor50feet. Pullthebagsooftherowunitsandweightheseed. UseTable4-4todeterminehowmuchseedshouldbe

collected rom each row unit. Use the seed tag to identiyhow many wheat seeds are in a pound. Each variety andpossibly each seed lot o wheat will be a diferent seedsize.

Adjustthesettingsonthedrillifnecessary.

Method 3. (least accurate) Calculate out how many poundso seed should be planted or each acre. For example, a targeto 35 seeds per square oot is 1,524,600 seeds per acre. I the

seed size is 10,000 seeds per pound, the total pounds peracre needed is 152 pounds per acre (able 4-3). Putaspecicamountofwheatseedintothedrillhopper

(either ll to a certain line inside the hopper or ll thehopper to the top).

Plantaspeciedarea,eitheroneacreorone-halfacre. Weighout200poundsofseed.Putseedintothehopper

until you have lled the hopper back to the speciedheight.

Weightheremainingseedtodeterminehowmanypoundswere added back to the hopper.


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2 5F e r t I l I z e r m a n a G e m e n t

increased disease incidence and severity, and lower yield.Additionally, excessive N may result in increased levels o Nin ground and surace waters, with negative environmental(and economic) consequences.

Rates and Timing. Wheat requires a small, but important,amount o N in the all. Tis requirement can almost alwaysbe met by soil N remaining ater the preceding corn orsoybean crop. Producers needing additional P may select Pertilizer sources containing N (or example, diammoniumphosphate, DAP, 18-46-0). In the unusual event where and

when corn yields greatly exceed (by at least 30 bu/acre) theexpectations built in to the corn crops nutrient manage-ment plan, residual N or the succeeding wheat crop willlikely be low. I the corn yield exceeds expectations, then20 to 40 lb N/acre should be added at or near planting. FallN ertilization becomes more important with late plant-ing (ater the rst week o November) in a wet all season

Photo 5-1. The wheat is at about Feekes 2 (Zadoks 21). Stand counts atthis stage can help determine how much N to apply or the rst applica-tion.

Section 5

Fertilizer ManagementLloyd Murdock, John Grove, and Greg Schwab

The most important rst step in your ertilizer manage-ment program is to take a soil sample. Except or nitro-

gen (N), your ertilizer and lime decisions will be based onthe soil test results. It is advantageous to take the sampleas soon as possible ater harvest o the previous crop tosupply the necessary phosphorus (P) and potassium (K) orthe seedling wheat plant. However, in drought years, soiltesting at this time can result in soil pH and K test valuesthat are articially low due to extremely dry soil condi-tions during August and September. Extension publicationAGR-189 gives recommendations on taking soil samples

under such conditions. Reer to Extension publicationAGR-1,Lime and Fertilizer Recommendations, or specicrecommendations based on soil tests.

NitrogenNitrogen is the nutrient requiring the most management.

Proper N rate and timing are important or high tiller num-bers and yield (Figure 5-1). Nitrogen deciency symptomsconsist o pale green (chlorotic) plants that are poorly til-lered (Photos 5-2 and 5-3). Excessive N can cause lodging,


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2 6 F e r t I l I z e r m a n a G e m e n t

and poor initial emergence (less than 25 plants per squareoot). Sucient all N stimulates early tillering, which is

important or high yields. Te all N rate should not exceed40 lb N/acre.

Nitrogen applied in late winter-early spring is most efec-tive or yield. Tere are two approaches that can be usedor spring N applications: a single application or a splitspring application. Research indicates that a split springapplication o N can increase yield by 3 bu/acre (althoughthis varies rom year to year), and split N applicationsreduce lodging potential. Split spring N applications arerecommended when possible, but equipment and logisticproblems cause some growers to make a single application.

When using the split N strategy, the irst applicationshould be made in late winter (mid-February to early March,Feekes 2-3, Zadoks 20-29) at a rate between 30 and 50 lb N/ac

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A Comprehensive Guide to Wheat Management in Kentucky

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