Figure 1. Winter wheat field in Central SD. April 23, 2018. Courtesy: R. Beck.
The winter wheat crop is rapidly greening up across South Dakota. It is a good sign that the crop made it through the winter and also the cold snowy spring that we experienced this year. Though small at this time, plants across the central part of the state, look healthy. Roots and shoots have healthy coloring and many plants have 1-3 tillers. This is an ideal scenario for winter wheat. The long fall of 2016 produced winter wheat plants with up to 7 tillers in the early spring of 2017. Plants with numerous tillers have higher moisture and nutrient requirements. The dryer climate of central and western South Dakota does not always receive enough moisture to support plants with high numbers of tillers. Plants with too many tillers and too much lush growth can also offer protection for plant pathogens allowing them to survive winter.
Monitoring wheat early and at regular periods throughout the spring and into summer can be a valuable investment for wheat producers. Proper scouting should include checking 3-4 different areas in each field, depending on the field size. If fields are very large, more checks may be needed to assess the crop condition with confidence.
Fields that are planted back into last year’s wheat residue can be more prone to some early season leaf diseases such as tan spot and powdery mildew. These diseases can be very detrimental to a wheat crop if environmental conditions are conducive for disease development. Fungicide applications are effective against these diseases. However, fungicide applications should only be made if disease is present. Since these diseases usually do not spread under warm dry weather conditions, producers may opt to monitor these diseases rather than make a fungicide application.
Stripe rust often moves into SD from the south if environmental conditions are right early in spring. Producers should be aware of reports of stripe rust and other rusts from states south of South Dakota. For instance, stripe rust has already been reported in Kansas this year. Stripe rust can persist in cool moist conditions like we have been experiencing this spring.
Knowing variety traits can help producers make disease management decisions. Varieties will have different disease resistance packages. This information can help producers with fungicide decisions.
Weeds and Insects
The cool spring has marginally slowed weed development. Many fields scouted had some winter annual weeds like pennycress, shepherd’s-purse, blue mustard, and downy brome. Kochia seedlings were spotted in numerous fields, although very small at this time. In a similar manner, the delayed spring has also resulted in low insect populations as they have yet to fully emerge. However, early season scouting should still occur to monitor for mite, aphid and cutworm populations.
Scouting wheat can also help producers assess the crops’ yield potential. The demand for nitrogen in winter wheat is dependent on growth stage and will usually increase in the spring. SDSU recommends 2.5 lbs. of nitrogen per bushel of wheat. Many winter wheat producers apply additional nitrogen in the spring if the crops’ yield has potential to exceed nitrogen availability. For best response apply nitrogen towards the end of tillering and just prior to jointing and stem elongation.
Careful Management Can Pay
Under normal moisture and temperature conditions wheat is a crop that will respond to management. A careful and regular scouting program on winter and spring wheat can catch problems early and help producers manage this crop for success. Refer to the 2018 SDSU Pest Management Guide for Wheat for more information on pest management of wheat.
Figure 2. Healthy developing winter wheat plant. April 23, 2018. Courtesy: R. Beck.