Early Season Wheat Disease Assessments

Updated: 15 May

We have begun our early season wheat disease assessments at the winter wheat variety trials in Wisconsin. Our approach for disease assessments follows the recommendations we made in the March 26, 2009 Wisconsin Crop Manager article, entitled, “Do I Need to Spray a Foliar Fungicide in Wheat in 2009?” These assessments are also a part of the thesis research for Karen Lackermann, Plant Pathology, to improve the decision management system for controlling wheat diseases in Wisconsin.

At Janesville and Lancaster, wheat growth and development currently ranges from Feekes 4-5 (pseudostem erection; Zadoks 30) to Feekes 6 (1st detectable node; Zadoks 31). In our assessments at those two locations, we have found symptoms of the Septoria leaf blotch complex, leaf rust, and stripe rust. The level of disease is relatively low and specifically, we have only noted symptoms in the lower canopy and nothing on the newest emerged leaf. At this range of growth stages, we do not recommend the use of foliar fungicides for Septoria or the rust diseases. Scouting over the next two weeks, however, will help to determine if these diseases are increasing in the canopy. Furthermore, the use of the thresholds we outlined in our Wisconsin Crop Manager article can help determine the need for a foliar fungicide as we move into flag leaf emergence.    

We have also completed our first assessments at the Chilton variety trial location.  Wheat was at Feekes 4-5.  Similar to the other locations, we observed Septoria leaf blotch, leaf rust, and stripe rust.  Of all the samples we have assessed, only 1 had symptoms of leaf rust on the newest leaf. Our recommendation is similar to Janesville and Lancaster at the moment. 

We will continue our assessments for the rest of the growing season including Feekes 7 (2nd detectable node; Zadoks 32), Feekes 8-9 (flag leaf emergence; Zadoks 37-38), and Feekes 10.51-11.1 (flowering to soft dough; Zadoks 60-75) at all of the variety trial locations and will continue to update you all on how wheat diseases are progressing around the state.   
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