Management for High Yield Winter Wheat (Eastern North America)

Seeding Rates

High density wheat stands are critical for high yields and helpful for weed control. In high yield environments, wheat growers typically seed 1.4 to 1.8 million seeds/acre where soil conditions are good and when seeding is done in an optimal timing window. In late-planted wheat, adjust seeding rates upward to the range of 1.8-2.2 million seeds/acre since there is less time for tillering.

Know the optimum head count at harvest for maximum yield potential to understand ideal seeding rates. The goal of stand establishment is 25-35 plants/ft2 with each plant producing 3 to 5 tillers. Maximum yield potential can be achieved with 60-80 heads/ft2.

Aim for stand uniformity – stand consistency comes back to good seedbed conditions and accurate seed placement with your planting equipment. Target a consistent planting depth of 1 to 1.5 inches.

Planting Date

Optimum wheat planting dates are based on regional recommendations along with conditions and experience on a grower’s own farm. The planting window for most regions is typically 2-3 weeks in length before yield potential declines. Delayed planting can occur for a variety of reasons, resulting in fewer fall tillers, greater risks of winter injury, and lower yield potential. High temperatures at planting can speed up germination rates but may result in fewer established seedlings when soil moisture is adequate. Low soil moisture at planting may slow germination and hinder early wheat growth.

Variety Selection and Seed Treatment

High yield starts with elite genetics adapted to the area. Other considerations like winterhardiness, disease or insect resistance, and lodging resistance are important to help protect yield. When using high seeding and nitrogen (N) fertilizer rates, resistance to powdery mildew is important. Always plant new, certified wheat seed and use seed-applied fungicide and insecticide treatments to protect seedlings from early pest pressure.

Crop Rotation

Wheat has the greatest potential for high yields when planted after soybeans or corn. Crop rotation breaks the disease and pest cycles of each crop and increases canopy competition for earlier and better weed suppression. More frequently, growers are planting rotations of corn, wheat and double-crop soybeans after wheat harvest, where three crops are harvested in two years.

Nutrient Needs of Wheat

Wheat performance is very responsive to good soil fertility and timely fertilizer applications due to its shallow root system. Every soil type has different capabilities to supply essential nutrients to high yield wheat plants. Fertile soils can only be highly productive if the physical structure (texture, density, porosity, drainage) and biological (microorganisms) properties of the soil are maintained.

Wheat prefers a soil pH between 6 and 7 for optimal growth. Manage soil pH for the crop with the highest pH need in the rotation. Primary nutrients for high yield wheat are nitrogen (N), phosphorus (P), and potassium (K). Removal rates for grain and straw are shown in Table 1. For secondary and micronutrients, wheat is a high demand crop for manganese (Mn), a medium demand crop for sulfur (S) – when straw is removed – and copper (Cu), and a low demand crop for boron (B), molybdenum (Mo), and zinc (Zn).

Fertilizer application rates are not the same as nutrient removal rates for wheat and wheat straw. Always soil test to help determine baseline levels of nutrients in the field. Wheat yield response to P and K fertilizer depends on soil nutrient test levels, organic matter, prior crop legume credits, and weather. Use state and local fertilization recommendations coupled with on-farm experience to develop a wheat fertilization plan.

Fertilize at the Start

Adjusting soil pH to a range of 6-7 maximizes nutrient availability and uptake, providing the mineral resources for optimum plant growth and grain production. To hit a target pH of 6.5 plan to apply lime 6-12 months prior to seeding.

Paying attention to the biggest nutrient needs of the plant starts prior to seeding. Growing high yielding varieties in high yield environments means total N, P, and K demand is greater. Phosphorus (P₂O₅) and potash (K₂O) fertilizers are most effective when banded compared to broadcast applications because it can help roots have better access to nutrients and helps prevent off-site movement of nutrients due to snow melt or rainfall. Cooler soils benefit most from banded or seed-placed P and K fertilizer applications.

Starter fertilizer containing 20-30 lbs/acre of P placed with the seed or banded at planting helps promote early season growth and tillering in the fall and improve winterhardiness. Potash (K₂O) fertilizers help promote strong stem growth, prevent lodging, and help promote plant development and good plant health. When starting with high or excessively high soil test K levels, response to additional K fertilizer will likely be minimal.

If broadcast spreading fertilizer, aim for uniform distribution of the applied fertilizer – spend time pattern testing spreader equipment to improve distribution. Many have found boomtype air applicators or liquid N application systems to be more accurate than spinning disk technology.

Nitrogen Powers Yield Potential

Nitrogen (N) is frequently the most yield-limiting nutrient for winter wheat. It promotes tillering and shoot number, drives photosynthesis, and is the building block of protein in the plant and grain. Wheat can use up to 1.0-1.5 pounds of nitrogen for each bushel of expected yield and utilizes 70-75% of the total nitrogen requirement between Feekes growth stages 6 and 10. The greatest amount of nitrogen should be available at that time.

In general, growers aiming for high wheat yields apply a total of 100-140 lbs N/acre. Managing N in wheat can be challenging because of yield and quality penalties for running short of N and the increased lodging potential when over-applied. When tiller counts are high (>70/ft2), a single application of N at Feekes growth stage 4-5 (prior to jointing) should be sufficient to maximize yield potential.

At planting, it is often beneficial to apply a small amount of N (20-30 lbs N/acre) to encourage early growth and fall tillering, especially if planting is delayed. Split applications of N to wheat often help maximize yield potential, especially if planted on light or sandy soils or if a stand is marginal and tiller counts are low (<70/ft2). A first application of 40-60 lbs/acre of N is applied prior to green up at Feekes stage 3. Then another 60-80 lbs N/acre is applied at Feekes stage 4-5.

What form of nitrogen should be used? The form of nitrogen is not as important as how accurately it is applied. Common forms of nitrogen used include ammonium sulfate, urea, and 32% or 28% liquid N. Apply a uniform rate across the entire application width. Liquid 28% N solutions may result in leaf burning but can be managed by using streaming or flood nozzles, keeping the N rate lower, or avoiding using 28% N tank-mixed with herbicides.

Growing wheat in high yield environments can lead to plant lodging, reducing harvestability and yield potential. Many growers use Palisade^® EC plant growth regulator (PGR) to reduce the risk of lodging and harvest delays and to protect yield potential of the crop. Palisade works by shortening stem internodes and thickening stem diameter resulting in shorter plants with a lower center of gravity that are less likely to lodge. Palisade is applied between Feekes GS 4-7 and can be tankmixed with many pesticides and liquid fertilizers.

Timing

Timing of pesticide products to control weeds, disease, or insects is critically important and growers may only have a 48-hour window. Be prepared by scouting frequently and having equipment ready to go when needed.

Weeds

Start clean, stay clean! Weeds emerging at the same time as the wheat crop are most likely to reduce yield potential. Keep weeds in check early in their life cycle and do not let weeds get too big. Use a burn down herbicide well before planting in no-till environments to eliminate weeds and volunteer corn. Use multiple tillage passes in a conventional tillage program if needed to start with a weed-free seedbed. The best cultural weed control strategy is to manage wheat seedings for quick emergence and vigorous early growth.

Recommendation: Apply Quelex^® herbicide at a rate of 0.75 oz/acre to actively growing wheat. Weed control is best when applied to weeds that are growing, and when wheat is at the 2- to 4-leaf stage, or less than 4 inches tall. Be sure to read and follow all label directions. Do not apply a total of more than 0.75 oz/acre of Quelex herbicide per season. Consider the fall weed management program before proceeding with spring treatments.

Diseases

Wheat disease management is key to producing high-yielding wheat crops. Disease control begins with variety selection and the use of a seed-applied treatment at planting. Wheat crops with 100+ bu/acre yield potential have a high density of stems and leaves, which – with wet weather – creates a favorable environment for disease development and growth.

A major disease of wheat is Fusarium head blight, also known as head scab, which is caused by Fusarium graminearum and other Fusarium spp. This disease occurs during flowering and grain fill stages of growth and is most prevalent with warm, wet weather conditions. A foliar fungicide treatment that protects the emerging flag leaf at Feekes stage 9 is most effective at protecting yield and grain quality.

Recommendations: Apply Aproach^® fungicide at 3-4 fl oz/acre between tillering and jointing (Feekes GS 4-6) for early-season disease control or suppression. Apply Aproach^® Prima fungicide at 6.8 fl oz/acre as the flag leaf emerges (Feekes GS 9) for optimal flag-leaf disease control. Apply Prosaro^® fungicide at early flower (Feekes GS 10.5) for improved control of Fusarium head blight.

Insects

The probability of severe insect infestations is relatively low in winter wheat. Regular field scouting is necessary to help identify insect issues early. Aphids are the most common insect pest in wheat. Aphids suck sap from plants and move barley yellow dwarf virus (BYDV) within a field. When aphid populations exceed thresholds (10 per foot of row with early green up and good conditions) a treatment should be applied to protect the wheat crop.

Big yield potential is driven by large inputs of sunlight energy and water. The ability to capture and use as much sunlight and water as possible is key to success. To do this means keeping plants healthy and having all essential nutrients available for use by the crop.

Yield contest growers are intensive thinkers about managing the crop. They work within a framework of soils, farm microclimates, and crop input options to promote high yield. Attention to crop needs is accomplished by frequent visits to the field to observe crop growth or to identify crop growth setbacks. Timely treatments with fertilizers and crop protection products can help push the wheat crop to perform at its highest potential. Using the best wheat genetics will give growers an opportunity to stretch yield limits on their farm.

Description:

• Germination, coleoptile, and first true leaf emergence.
• Development of multiple leaves and seminal root system.

Management:

• Evaluate plant stands and uniformity of establishment – target is 25-35 plants/ft2.
• Observe weed growth and monitor for aphids and Hessian fly damage – take control measures as needed.
• Using a drone, capture pictures of vegetation development to identify areas of the field with potential nutrient deficiencies, poor soil characteristics, low or high soil moisture, and weed or pest issues.

Description:

• Primary tiller formation begins.
• Winter dormancy and vernalization.
• Spring growth and secondary tiller formation from primary tillers.

Management:

• Tillers contribute 30-50% of yield potential – tillers formed between emergence of 4th and 6th leaves on the main stem have the best opportunity to form grain and contribute to yield – late forming tillers may fail to produce grain, especially when under stress.
• Apply nitrogen fertilizer in the fall to stimulate early growth and tillering.
• Check stands for winter injury and determine if herbicide is needed to control weeds.
• Early spring applications of nitrogen fertilizer prior to initiation of green-up will promote post-winter tillering and increase stem density of the crop (apply up to 30% of total N need at this stage).

Description:

• Stem elongation begins and stem nodes form (jointing, Feekes 6) when the growing point moves above the ground surface and plants become more erect – also known as the green-up stage.
• Feekes 8-9 - flag leaf emergence.
• Feekes 10 – booting stage where a fully grown head is seen as swelling in the stem area just below the flag leaf.

Management:

• Apply additional nitrogen as needed prior to Feekes stage 6 to supply sufficient N for the upcoming stem elongation and heading stage when nitrogen demand is greatest.
• Growth regulators that limit upper stem elongation can be used to help prevent lodging of a wheat crop.
• Scout for weeds, insects, and foliar diseases during this time and initiate control measures when needed.
• Application of nitrogen at flag and boot stage may increase grain protein and increase the size of seeds produced.
• Fungicide application to protect the flag leaf can be made during the flag leaf and booting growth stages – the flag leaf is 75% of effective leaf area at this stage and is critical for high grain fill potential.

Description:

• Heading – inflorescence and flower organs are fully developed and emerge from the stem.
• Flowering and anthesis – pollen producing anthers extrude from the floret and flowers are pollinated beginning with the middle spikelets.

Management:

• Wheat is susceptible to Fusarium head blight at this time and fungicides can effectively minimize damage from this disease when applied during the onset of flowering.
• Pollination takes about 4 days for an individual head after which grain fill begins.
• Grain fill duration depends on temperatures, soil moisture, or plant stress and can take anywhere from 13 to 20 days or more.

Description:

• Ripening and senescence – kernel moves from milky to soft dough to hard dough stages reaching physiological maturity when kernel moisture content is below 30%.

Management:

• During ripening plants continue to need adequate soil moisture to make sure grain fill continues without interruption and maximum yield potential is reached. If irrigation is available, use it to avoid water stress in the ripening stage of growth.
• Harvest begins when kernel moisture drops to the 15% level or lower and storage is safe when grain moisture is in the 12-14% range.