Gray Leaf Spot of Corn

PATHOGEN FACTS

Gray leaf spot (GLS) is a common fungal disease in the United States caused by the pathogen Cercospora zeae-maydis in corn.
Disease development is favored by warm temperatures (80 °F or 27 °C) and high humidity (relative humidity of 90% or higher for 12 hours or more).
Cercospora zeae-maydis overwinters in corn residue, allowing inoculum to build up from year to year in fields.
Cropping systems with reduced- or no-till and/or continuous corn are at higher risk for gray leaf spot outbreaks.
Conducive weather conditions encourage the rapid spread of disease near the end of summer and early fall when corn plants allocate more resources to grainfill.