Wisconsin Winter Wheat Disease Update – June 19, 2013

Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison

This week I scouted winter wheat in variety trials in Lancaster and Arlington Wisconsin on June 19, 2013.  Wheat has completed flowering in these locations and most locations in southern Wisconsin.

In Lancaster, stripe rust was present at low levels.  Previously, no rust had been found at this location.  I saw low incidence and severity (<10% leaf area affected) in this location.  Note that fungicide recommendations are not recommended, or legal in most cases according to the label, after flowering has completed.  Continue scouting in areas in central and northern Wisconsin where wheat is flowering.  If rust is noted in these locations where wheat has not flowered or is currently flowering monitor severity on flag leaves and make a decision to apply a fungicide.

I also found several wheat heads with symptoms and signs of Fusarium head blight or scab at the Lancaster location.  Wheat in this location is past the window of opportunity to apply a fungicide.  Wheat that is currently flowering in central or northern areas of Wisconsin is currently at low risk for Fusarium head scab according to the Fusarium head blight risk assessment tool (http://www.wheatscab.psu.edu).  As of this writing, the tool is showing low risk for the entire state of Wisconsin.  This situation should be monitored closely over the next week or so in areas where wheat is flowering.  The weather pattern is projected to be warm and very humid, which can favor Fusarium head blight.  If wheat is flowering, and in an area of risk, then a fungicide application might be considered.  DO NOT use fungicides that contain strobilurin fungicides (FRAC 11) for control of head scab, as increased risk for DON (deoxynivalenol) can result. A triazole fungicide such as Prosaro, Caramba, Proline, or similar product applied during the onset of flowering to 3-5 days after will be most effective.  To learn more about Fusarium head blight and how to manage the disease, visit http://fyi.uwex.edu/fieldcroppathology/.