Northern wheat production is enjoying the spring weather, but is also susceptible to disease and should be monitored by growers. Shawn Conley, University of Wisconsin Extensionsoybean and wheat specialist, says winter wheat in Wisconsin is looking very good across the majority of his wheat field trials. However, there has been some evidence of powdery mildew in some of these trials.
He says this is an important period for some early season management, specifically for decisions for disease management. “It starts with knowledge of the relative susceptibility of your wheat variety against powdery mildew,” he says. “With that knowledge, a second step is to then determine how severe and where in the wheat canopy are symptoms of powdery mildew being noted.”
He says at Feekes 4-5, the recommendation for the use of a foliar fungicide is based on the appearance of symptoms of powdery mildew on the newest (i.e., upper) leaf. He suggests these steps for checking for the disease: Scout by examining approximately 100 leaves in a field from different locations, then assess the severity for each leaf by counting the number of powdery mildew pustules.
If the average number of pustules is 10 or greater, this may indicate the need for use of a foliar fungicide, he says. “In most years, we often see symptoms of powdery mildew in the wheat canopy, but typically only in the lower canopy due to the microclimate and varietal differences,” he says. “Disease management decisions at these earlier growth stages need to take into account the assessment of the most appropriate leaf material that may impact the flag leaf later in the growing season.”