Don't cheat your wheat

Written by Scott Wilburn on .

In the Midwest, wheat is one of the crops that most responds to intense management. Many of those management steps occur after wheat breaks dormancy in the spring.

When wheat comes out of dor­mancy, the first order of business is to check the stand. A general eval­uation will reveal if large areas did not survive winter and whether lat­er-emerging plants were able to fill in. Next is a proper stand count. A rule of thumb for maximum wheat yields is to have approximately 70 to 80 plants and tillers per square foot. Knowing your stand count not only indicates the health of your crop but can also be used to de­termine nitrogen timing. In drilled wheat with 7.5-inch rows, a square foot is 19.2 inches. If you find your­self without a tape measure, this is roughly shoulder width for many of us. Count each plant and its tillers in that square-foot area. If you count 70 to 80, you may choose to delay a nitrogen application. Fewer than this may necessitate an early nitrogen application to encourage additional tillers. Randomize where you take stand counts by throwing something like a hoop or a ball and counting wherever it lands.

Nitrogen management in wheat focuses on rates and timing. Historically, wheat fields received all of their N in one application following green-up. This is often still the case and can result in excellent yields. In some situations, though, a split application should be considered. When a field has a low tiller count and requires early nitrogen, it is probably too soon to apply everything. A split application helps prevent loss of nitrogen that will be needed later in the season. High rates applied early, combined with good growing conditions, can encourage vegetative growth to the point that plants lodge later in the season. Splitting the nitrogen appli­cations helps mitigate this poten­tial issue. Nitrogen rates generally should total around 90-100 pounds in the spring, and some producers have seen benefits of going as high as 120 pounds. Using an N source with a urease inhibitor to protect loss from volatility is advised. Sulfur should also be added in the form of ammonium sulfate or ammonium thiosulfate. Avoid elemental sulfur for wheat top-dress because it is not immediately available.

Wheat is not the only plant in your field that responds to nitrogen. Henbit, chickweed and other winter annual broadleaves will compete for fertilizer and other resources. Top yields will not occur if weeds are not controlled. Winter annuals may also be sprayed in the fall, but you still need to scout fields for garlic in the spring. Garlic is not terribly competitive, but it destroys quality and must be controlled.

Herbicides may be sprayed as a stand-alone pass or combined with liquid nitrogen. They may also be combined with insecticides to help control aphids and other insect pests. Aphids in wheat are best known for transmitting barley yellow dwarf. This yield-robbing disease is viral, so fungicides won’t help. You must control the disease vector, which is the aphid. Keep in mind, aphids also work on wheat fields in the fall. They often do more damage during that time peri­od, so do not solely rely on a spring management strategy.

Managing fungal disease is imperative to achieving top yields and sometimes, more importantly, top-quality wheat. Fungal diseases such as common rust and its more aggressive cousin, striped rust, can severely affect yields. Fusari­um head blight or “head scab” is extremely detrimental to yields but can also affect quality of wheat to the point of being unmarketable.

Fungicides have often been viewed as an optional input for wheat, but many producers now consider them table-stakes, espe­cially the later applications made for scab. The benefits to quality and test weight more than justify their use, and often, there is a yield increase as well.

Disease threat reports and scouting have been helpful tools when timing fungicides, with the exception of fusarium head blight, which can only be controlled with an application during the small window of flowering. New products allow a wider application window that begins at 50% head emergence. This earlier window not only makes it easier to achieve a timely appli­cation for scab, but it also helps with diseases that may already be present.

Raising high-yielding, high-qual­ity wheat involves several import­ant activities, and correct timing is imperative to success. MFA’s Crop-Trak scouting program is an excellent tool to help make sure these decisions are being made on schedule. Weather too often gives us a narrow window to get every­thing done, so being proactive is a must. Crop-Trak consultants and agronomists make weekly trips to the field, which helps make sure none of these steps are missed or ill-timed. Contact your local MFA for more information.