Establishing and assessing winter wheat stands

Introduction

Wheat is the third largest field crop by acres planted in the United States, behind only corn and soybean. Winter wheat is most often thought of as a grain cash crop but there are many uses for winter wheat, and crops planted for each of these uses can require different production strategies.

Seeding rate and planting date are two of the main factors that should be considered when planting wheat for grain or for an alternate end use. Growers should also consider that planting date, seeding rate, and minimum sustainable plant populations vary by region due to differences in soil type, expected precipitation, and other environmental factors. For example, in most areas, the optimum seeding rate for a winter wheat crop is lower if planted earlier in the fall and higher if the crop is planted later in the fall or in early winter.

Winter Wheat End Uses

While winter wheat is often considered to just be a grain crop, it has many other uses:

• Graze-out winter wheat – late fall, winter, spring, and summer pasture.
• Cover crop – either as a stand-alone cover crop or in combination with other cover crop species.
• Alternative forage – haylage, silage, hay.
• Dual purpose – pasture and grain production

A wheat crop could be used as a valuable alternative forage, both as hay and haylage, and as a pasture crop for cattle and sheep. Additionally, when used as a cover crop, winter wheat can help reduce soil erosion, reduce nutrient loss, and provide cover that can reduce weed pressure.

Establishing Winter Wheat Stands

Product Selection

Selecting high quality seed is important for germination and stand establishment. Purchasing certified wheat seed can help ensure the seed is free of weed seed, certain diseases, that it has a potential germination level over 85%, and has a test weight of at least 56 lb/bu or more.¹ Evaluating and selecting wheat products with high yield potential, high test weight, grain quality, forage production, winter hardiness, and resistance or tolerance to insects and diseases in your geography is the first step to producing maximum yield potential. Since each seed product has specific strengths and weaknesses, more than one product should be considered. Choosing multiple products of varying maturities can help manage risks associated with agronomic challenges such as late spring freezes and diseases, such as Fusarium head blight, and can aid in harvest scheduling. Seed treatments containing fungicides are recommended as they can reduce the incidence of seedling and seed-borne diseases, thus improving overall stand establishment. Seed treatments containing insecticides may be beneficial with early fall plantings as they can control aphids.

Planting Date

Winter wheat should be planted early enough to allow development of an adequate number of fall tillers to support high yield potential and avoid a freeze, but late enough to avoid potential damage from fall insects and diseases. Tillers produced in the fall are likely to produce grain heads with high test weight kernels. For example, aphids and Hessian flies are insects that damage wheat. Aphids can vector barley yellow dwarf virus (BYDV), a yield-robbing viral pathogen of winter wheat. At least one night with temperatures below freezing is required to reduce the development of Hessian fly and aphid populations, which may then result in a reduction of infection from some diseases. Planting dates for winter wheat grain crops are always recommended after the Hessian fly free day for the production area. This strategy is not as important for wheat grown as a forage.²

Seeding Rate

Some wheat producers may determine their seeding rate based on pounds per acre. However, because seed size varies, more accurate seeding rates can be calculated using seeds per acre. Like planting dates, recommended seeding rates vary from state to state and even within a state. For example, in low rainfall areas such as western Kansas, seeding rates are generally lower than in central and eastern Kansas. In western Kansas (a low yield environment) recommended seeding rates range from 600,000 to 900,000 seeds/acre (40 to 60 lb/acre with 15,000 seeds/lb products). Recommended seeding rates increase to 705,000 to 900,000 seeds/acre in central Kansas (a moderate yield environment) and further increase to 900,000 to 1,250,000 seeds/acre in eastern Kansas (a high yield environment). Under irrigation, the seeding rate recommendation may increase to 1,350,000 seeds/acre.¹

In eastern states with higher rainfall areas like Michigan, the recommended seeding rate for winter wheat for grain production is between 1.2 and 2.0 million seeds/acre. The lower recommended seeding rate should be used when planting early in the season. As the planting date is pushed later in the season, it is recommended to increase seeding rates because the crop has less time to produce healthy tillers which are needed for a high yield potential crop. If the planting date is delayed into the second half of October, the seeding rate should increase by up to 1.6 million seeds per acre.³

Seeding Depth

Wheat seed should be planted one to two inches deep, and some semidwarf varieties with shorter coleoptile lengths should not be planted more than one and a half inches deep.⁴ Planting short coleoptile type wheat varieties any deeper may result in seedling death due to premature underground leaf opening, or poor tiller development, and reduced winter survival.

Fertility

Proper fertility is critical for profitable winter wheat production. The first step of any fertility plan should be soil testing with a reputable soil laboratory. In most production environments, nitrogen (N) is the most yield-limiting nutrient, followed by phosphorus (P) and sulfur (S). Excess N and N deficiency can both cause production problems for winter wheat. Excess N can cause lodging and harvest losses, while N deficiency can reduce yield potential.

When soil nutrient levels have been determined, a yield goal should be established. This goal will be influenced by the specific use for the crop. For example, winter wheat takes about 1.75 lb N/bu to produce a bushel of grain. For other uses, winter wheat graze-out production takes 15 lb N/ton of wheat pasture per acre, winter wheat hay requires 28 lb N/ton, and winter wheat silage needs 10 lb N/ton per acre produced. The amount of N present in the soil test results and any manure credits can be subtracted from the recommended N levels to determine how much N, if any, should be added to the soil.⁴

A top dress N application can be made as the crop breaks dormancy but before the crop starts to joint. This should allow growers time to adjust the yield goal if winter growing conditions have increased yield potential or to add any required N that was not applied prior to planting. After wheat breaks dormancy, an additional soil test can help determine the amount of N needed in the N top-dress program.

Establishing Winter Wheat Stands for Specific Uses

Grain

• Planting date is determined by the Hessian fly free date for the production area.
• Planting rate is determined by planting date and yield expectation.
• Very late planting dates may require a 2-times planting rate to compensate for reduced fall tillering.
• Freezing weather after germination (vernalization) is required to trigger the wheat plant to produce viable wheat heads in the spring, which are needed for grain production.
• Use a soil test to determine the correct amount of fertilizer to apply to meet all essential plant nutrient levels for the yield goal.

Graze-out Pasture

• Planting date should be one to one-and-a-half months earlier than wheat planted for grain production.
• Increase seeding rate 1.5 to 2 times over a grain-only production system.
• Select a wheat variety that has been developed for a graze-out system.
• Awnless wheat varieties have several advantages over awned varieties in a graze-out system.
• Wheat used for grazing removes more soil nutrients than a grain wheat crop.⁵

Hay, Haylage, Baleage, and Silage

• Planting dates can start one to two weeks earlier than wheat planted as a grain crop, since Hessian fly lodging damage is less of a concern when the wheat crop is harvested in the late vegetative through the early heading growth stage.
• Increase seeding rate 1.5 to 2 times over a grain-only production system.
• Wheat varieties that are tall and produce a lot of vegetative top growth produce more hay or haylage.
• Use a soil test to determine the amount of fertilizer to apply to meet essential plant nutrient levels for the yield goal.
• The later the crop is planted, the higher the seeding rate should be.
• For hay or silage production, apply limited N at seeding and 60 to 80 lb N/acre in late winter or early spring.
• Winter wheat can potentially produce one to two tons dry matter (DM) of hay per acre at the boot stage, or two to four tons DM at the soft-dough stage.
• Cut hay at the boot to early heading growth stage. The earlier the wheat is harvested as a hay crop, the higher the hay protein levels should be.
• Dry hay needs to be wilted to less than 20% moisture content, though 15 to 18% moisture content is often better depending on the bale type and size.
• Wilt to 50 to 60% moisture content for baleage and 60 to 65% for chopped silage, depending on type of storage structure.
• Wheat can be direct chopped as silage at the soft dough stage.⁶

Stand Alone Cover Crop

• Should be planted earlier than wheat planted for a grain crop.
• Planting dates are a few weeks earlier than used for a rye cover crop.
• Earlier planting dates need less increase in planting rates.
• Drill 60 to 120 lb/acre (1 to 2 bushels) into a firm seedbed at one to one-and-a-half inches depth.
• Broadcast at a rate of 60 to 160 lb/acre (1 to 2.5 bushels) and disk lightly or cultipack to cover seed.
• Increased planting rates and early planting increases weed suppression and decreases soil erosion.
• Don't apply a spring top dress N fertilizer unless the wheat is used in a livestock grazing system or harvested for a grain crop.
• Wheat is less likely to become a weed problem in a crop rotation than barley or rye.⁷

Part of a Cover Crop Mix

• For an excellent cover crop seed mixture, include winter wheat with other small grains or legumes such as hairy vetch and sweet clover.
• Seeding rates for wheat can be decreased by half if used in a mixed cover crop.⁷

Dual Purpose, Pasture and Grain

• In a dual-purpose system, seeding should be two to four weeks earlier than if the wheat were planted as a grain-only crop.
• Earlier planting dates need less increase in planting rates.
• Depending on the intensity of the grazing program, the planting date, and soil moisture, plant 50 to 100% more seeds per acre than the seeding rate for grain production alone.
• Irrigated fields and areas with high rainfall may need planting rates of 90 to 120 lb/acre.
• Depending on soil moisture and fall temperatures, grazing can begin four to six weeks after planting.
• Before grazing, wheat plants need six to 12 inches of growth.
• Select varieties with profuse tillering, rapid and upright fall growth, and rapid regrowth.
• Use a soil test to determine the correct amount of fertilizer to apply to meet essential plant nutrient levels for the yield goal.
• In addition to the N needed for a grain-only crop, add 30 to 40 lb N/acre for every 100 lb of beef gain removed from the field to supply the needs of the forage crop.
• A split application of N in both the fall and spring growing seasons is often needed, especially in sandy soils, with 60 to 80 lb N/acre in the early spring to increase the forage crop production.⁸

Assessing Winter Wheat Stands

In the spring, winter wheat stand evaluations should focus on both plant population and plant health. When evaluating the stand, the average number of plants per square foot, stand uniformity, and number of tillers should be measured. To obtain an accurate stand count, be sure to allow plants enough time to green up and resume growth. Additionally, take multiple counts across a field in each of the different growing environments to account for the variability in winterkill.

When and How to Determine a Viable Winter Wheat Stand

First, determine when and where to assess the winter wheat stand:

• Wheat breaks dormancy at a soil temperature of about 39 °F. Allow about 10 days to 14 days of warm weather after green-up begins before counting stands.
• It is important to look at multiple areas across a field to understand both the variability and the amount of area with winterkill issues. An accurate assessment is needed to determine if the crop should be terminated.

Second, calculate the number of plants per square foot as follows:

• Look for viable green leaf tissue aboveground. Look for firm white or light-green stem tissue or crown tissue underground along with a strong, healthy, white root system.
• Using a yard stick, count the number of healthy plants along 3 ft of row. Repeat this procedure in several locations throughout the field, and then average those results to determine the average number of plants per 3 ft of row.
• Multiply that number (plants per 3 ft of row) by 4, and then divide by the row width (in inches) to determine the number of plants per square foot. For example, in a 7-inch row spacing, if the average number of plants is 44 plants per 3 ft row length, the calculation would be:
  (44 plants x 4) / 7 inches row width = 25.1 plants per square foot

Third, determine viability:

• For grain production, a stand with 24 or more healthy plants per square foot should be enough to help maximize grain yield potential in most production areas.
• If the stand is relatively uniform across the field, 15 healthy plants per square foot should produce have the potential to produce a reasonable grain yield.
• A stand with 12 to 15 healthy plants per square foot is the minimum that should be considered for grain harvest. A lower wheat stand population should be terminated and planted to another crop.
• A grazing or forage crop requires a 50% greater stand to help drive high-yielding forage production.⁹

Variables that Affect Winter Kill in Winter Wheat

• Winter kill is most likely to occur in areas with little snow cover or in fields with little to no standing stubble to collect snowfall.
• Survival can vary greatly across a field and is highly dependent on topography.
  • Areas in a field that are low and protected often have less winterkill.
  • Areas that are on hill tops with no protection from wind often have more winterkill.
  • Terrace tops also have poor protection from wind and have an increased potential for winterkill.
  • Areas with poor surface drainage, with standing water or ice for extended periods, can have more winterkill because crowns and root systems suffocate from the lack of oxygen.
• Different wheat products also have different abilities to survive winterkill.
• A delayed planting date can reduce crown development which can also increase the occurrence of winterkill.
• Insect and disease damage can cause increased winterkill issues.¹⁰

When evaluating a winter wheat stand, every year is different. When evaluating wheat population, growers should consider the crop’s intended end use and environmental conditions. Always consult your local agronomist or local extension winter wheat specialist to help assess winter wheat stands and evaluate other cropping options when deciding if a winter wheat crop should be terminated due to winterkill.

Sources

¹Paulsen, G.M., Sears, R.G., Shroyer, J.P., et al. 1997. Wheat production handbook. C-529. Kansas State University. https://bookstore.ksre.ksu.edu/download/wheat-production-handbook_C529

²Pennington, D., Nagelkirk, M., and Sing, M. 2022. Planting the 2023 wheat crop. Michigan State University Extension, Wheat. https://www.canr.msu.edu/news/planting_winter_wheat_crop

³Raymond, C., Knott, C. and Murdock, L. 2022. “Dusting in” wheat in drought conditions. University of Kentucky, Kentucky Grains Info. https://www.kygrains.info/blog/2022/10/21/dusting-in-wheat-in-drought-conditions

⁴Wheat, winter – grain. Agronomic Commodity Crops, Crop File: Soil Fertility & Plant Nutrition. https://cropfile.servitech.com/crop-files/1-00-soil-fertility-plant-nutrition

⁵Shroyer, J.R., Dhuyvetter, K.C., Kuhl, G.L., Fjell D.L., Langemeier, L.N., and Fritz, J.O. 1993. Wheat pasture in Kansas. Kansas State University Research and Extension, C713. https://bookstore.ksre.ksu.edu/download/wheat-pasture-in-kansas_C713

⁶Henning, J., Teutsch, C., Smith, R., and Phillips, T. 2021. Growing wheat for forage. University of Kentucky. AGR-263. https://forages.ca.uky.edu/files/wheat_for_forage_agr263.pdf

⁷Bowman, G., Cramer, C., and Shirley, C. 2012. Managing cover crops profitably, 3rd Edition. Winter Wheat Handbook Series Book 9. Sustainable Agriculture Research and Education (SARE). https://www.sare.org/publications/managing-cover-crops-profitably/nonlegume-cover-crops/winter-wheat/

⁸Lollato, R.P., Marburger, D., Holman, J.D., Tomlinson, P., Presley, D., and Edwards, J.T. 2017. Dual purpose wheat: management for forage and grain production. Oklahoma State University Extension. PSS-2178. https://extension.okstate.edu/fact-sheets/dual-purpose-wheat-management-for-forage-and-grain-production.html

⁹Luce, G.A. 2019. Evaluating winter wheat stands after a tough winter. University of Missouri, Integrated Pest Management. https://ipm.missouri.edu/croppest/2019/3/winterWheat/

¹⁰Winter Damage. Kansas State University Research and Extension.https://www.sunflower.k-state.edu/agronomy/wheat/winter_damage.html

Websites verified 05/24/2024. 1710_391697