Gray Leaf Spot
(Cercospora zeae-maydis)
Symptoms: Lesions may appear during reproductive growth stages, but usually not until several weeks after silking. Small lesions will develop on lower leaves initially, becoming tan-colored and elongate parallel to leaf veins giving a rectangular appearance. Lesions can eventually coalesce across the entire leaf.
Risk Factors: Disease is favored by warm, wet/humid conditions. The pathogen overwinters in corn residue, so it can become problematic in continuous corn.
Management: Practice rotation and tillage, where able, on infect debris. Plant resistant hybrids and when practical, fungicides may be applied (fungicide efficacy table).
