Alyssa Koehler, Extension Field Crops Pathologist; akoehler@udel.edu
A lot of corn across the area has begun to tassel. Scouting fields at this time can be helpful to decide if a fungicide application will be economical. When considering economics of a fungicide application, it is important to know your potential for disease based on environmental conditions and hybrid selection. Hybrids with higher resistance may not need a fungicide. In dryland fields, the hot, dry weather of the past week has stalled some of the disease pressure that we were beginning to see at the end of June. Irrigated fields keep enough moisture and may still be seeing some development of Grey Leaf Spot or possibly Northern Corn Leaf Blight. When scouting, look at the ear leaf or two leaves below. If you have lesions on over 5% of the leaf surface on half of the plants or more, you may want to consider a fungicide application. If applying a fungicide, application is typically recommended at VT/R1 timing for greatest chance of economic return.