Scouts continue to find tan spot in both winter wheat and spring wheat in their second week of scouting. There were no reports for Septoria spp. or leaf rust. The reported incidence and severity of tan spot increased a bit from the previous week. The risk assessment models mirror their findings as conditions for septoria and leaf rust were not as favorable as they have been for tan spot.
If you have not completed weed control in spring wheat yet, consider tank-mixing half a labeled rate of a registered fungicide with your weed control program to control early season tan spot in spring wheat when tan spot can found in your fields.
Winter wheat is flowering or Feekes 10.51 in the southern half of Minnesota. To date, the risk model for FHB continues to be trending low, largely because of the cooler temperatures rather than the absence of precipitation. The immediate forecast continues to indicate a low risk of FHB.
However, the application of a fungicide at Feekes 10.51 to suppress FHB is the final opportunity to controls leaf diseases like tan spot, Septoria spp., and leaf rust. Previous research has shown that control of the leaf diseases usually pays in the case of winter wheat. Therefore, I suggest you scout your winter wheat now and consider a fungicide application if any leaf diseases can be found in the lower canopy.
--Jochum Wiersma, Extension Agronomist, University of Minnesota Crookston
For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu
For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org