The blast furnace that was the weather for the past few days, the variability in precipitation received in the preceding week or weeks, and the immediate forecast all point to shorter leaf wetness durations. This, in turn, means less risk of FHB infections for the remaining spring wheat acres that have not reached anthesis yet. Meanwhile, Bacterial Leaf Streak (BLS) is thriving in these windy, humid conditions and can be found across the region. Leaf rust has been found at extremely low levels in a few spots in the Red River Valley, while a few FHB infections were found in the winter wheat variety trials on the Northwest Research & Outreach Center.
It will be a difficult decision whether to spray a fungicide to suppress FHB if drought stress becomes more evident in your fields with each passing day. Therefore, the advice this week is as follows:
Spring Wheat - Apply a fungicide at Feekes 10.51 (beginning of anthesis) if you find either tan spot, Septoria, or leaf rust present and your variety is rated a 5 or worse for any of these three diseases in the Minnesota Variety Trials, or if your variety is rated susceptible or very susceptible to FHB (a rating of 5 or worse). Switch to a premium fungicide if corn harvested for grain was the previous crop.
The first oats fields in the southern half of the state have been windrowed, and I expect the first winter rye and winter wheat to be harvested this week. This will, therefore, likely be the season's last small grains disease and pest update. Good luck with the harvest and stay safe.
Source : umn.edu