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Overnight leaf wetness creates ideal conditions for gray leaf spot

An agronomist is sounding the alarm as environmental conditions favor a foliar disease in corn.

Ron Geis with Corteva Agriscience says gray leaf spot thrives in warm, humid, and wet weather.

“The inoculum is here, it overwinters. So it’s already in the fields. It just needs that 11, 12 hours of leaf wetness before it really propagates.”

He tells Brownfield if dew sets in during the evening, it could stay on the leaf until the middle of the next morning.

“So now we’ve got that 12-hour cycle that gray leaf spot really thrives in.”

Geis says growers can protect yield by applying a foliar fungicide when corn is tasseling.