Numerous reports of spraying fungicides on corn have come in, say Anne Dorrance, Dennis Mills, and Pierce Paul, Ohio State University.

This is surprising in many cases because many of the corn fields look the cleanest they have been in a long time. Common rust in particular is at very, very low levels from Kentucky up through Ohio. Foliar diseases can cause significant yield losses if infection occurs between two weeks before to three to four weeks after tasseling. The earlier the disease starts in the field the greater the yield loss. It is important to keep the upper leaves and husks of the plant as disease-free as possible during the grain filling growth stage. Large yield losses only occur when foliar diseases attack the leaves above the ear leaf before mid-dent growth stage. Sweet corn growers routinely use fungicides, and seed producers growing susceptible inbreds have shown large yield increases by controlling leaf diseases with fungicides.

Fungicides are registered for the control of northern corn leaf blight, southern corn leaf blight, northern leaf spot, common rust and gray leaf spot.