Damon Smith, UW-Madison, Extension Field Crops Plant Pathologist
Stripe rust is increasing in incidence in some Wisconsin locations, while the overall severity (area of leaf covered by yellow spore-producing pustules) remains low. At the ArlingtonResearch Station location, susceptible varieties in a uniform variety trial have high incidence and high severity with damage already reaching flag leaves. Wheat in surrounding fields is also beginning to show higher levels of stripe rust incidence.
Here is a new 2 minute video update about stripe rust and scouting winter wheat at this growth stage.
Stripe rust can be very yield limiting when it advances to the flag leaves before head emergence. Humid conditions and rainy weather will provide conditions favorable for stripe rust increase over the next week. Now is the time to scout winter wheat fields in the state and determine the incidence and severity of stripe rust in the lower canopy. By scouting the lower canopy, you can get an idea of how much risk there will be for stripe rust moving up to the flag leaf. Fungicides will be most effective when applied to wheat before stripe rust advances to the flag leaf. While scouting also note the growth stage of the wheat crop. This will be helpful in making fungicide application decisions.