Anthracnose Leaf Blight, Goss’s Wilt found in Iowa
Warm weather with frequent precipitation favors gray leaf spot and northern leaf blight, both of which both reduce yield. Moreover, the earlier in grain fill that these diseases occur, the greater the yield loss. Because much of the corn was planted late this season, tasselling will likely occur towards the end of July, so we could be at risk for yield loss due to disease. While you are out scouting, check for disease development in the lower canopy, particularly gray leaf spot and northern leaf blight. This is a good indication that conditions are favorable for disease development and a fungicide application between tasseling and ‘brown silk’ (blister stage) should be considered, particularly if the hybrid is susceptible to disease. Moreover, there is a greater chance of a return on investment with a fungicide application when disease risk is high.