The wheat in southern Kansas ranged between the flag leaf emergence and boot stages of growth this week. Most fields in central Kansas are at or near flag leaf emergence. These growth stages signal the critical time for growers to be evaluating the need for fungicides for leaf disease management.
At a regional level, both leaf rust and stripe rust were reported in Texas as early as February and March but so far Oklahoma is only reporting low or trace levels of these rust diseases.
The disease levels have also been low locally in Kansas. I visited fields Sumner, Reno, McPherson, Marion, and Dickinson counties this past week and found only trace levels of powdery mildew, Septoria tritici blotch, and tan spot lower in the canopy.
In southeast Kansas, Doug Shoup, Kelly Kuzel, and Josh Coltrain (K-State Research and Extension), reported trace levels of stripe rust in several fields in Labette and Neosho counties this week. The stripe rust was reported on the variety Everest, which is known to be susceptible to stripe rust after the changes in the stripe rust population last year. This report of stripe rust is important and growers in this area should carefully monitor their fields for signs of disease.
There are some things to consider when considering fungicides this year:
- Be sure to evaluate the yield potential of your wheat. If you have experienced weather conditions (freezing temperature or drought) that make you question the yield potential of your crop, you may want to be more conservative when considering additional inputs.
- At this time, the risk of severe leaf rust or stripe rust is low or moderate. If disease is detected in the mid-canopy at the heading stages for growth, previous research indicates that there is about a 50 percent chance of a 10 percent yield response. If there are no reports of regional outbreaks of disease and the disease is not present at heading, the chances of 10% yield response are low (approximately 20% or less).
- There are a lot of excellent or very good products available for leaf disease management in wheat. The cost of fungicides varies significantly and the decision to apply is often influenced by product cost. Take a little time to investigate your product options and costs. The information about product costs will help you make the final decision when considered along with yield potential of the crop and yield benefit of the fungicide.
- More information about making fungicide decisions in wheat and fungicide efficacy can be found in the K-State Extension publications below.