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College of Food, Agricultural, and Environmental Sciences


Killing Frost, Cooler Fall Temperatures Impacting Corn Harvest

October 9, 2009

COLUMBUS, Ohio – A recent killing frost in some parts of Ohio may have impacted the corn crop, causing development to shut down prematurely, potentially reducing yields.

Fortunately, says Ohio State University Extension state corn agronomist Peter Thomison, most of the crop has reached physiological maturity -- the stage at which maximum kernel dry weight is achieved.

"Corn killed by the frost prematurely will reach maturity, albeit at a much higher kernel moisture content," said Thomison, who also holds an Ohio Agricultural Research and Development Center appointment.

The real issue now is how much the cooler temperatures will affect grain moisture. Harvesting when moisture content is too high could damage the combine could damage the grain in the threshing and shelling processes.

"Some of the crop that has been harvested so far has high grain yields, but with a high moisture content – high 20s," said Thomison. "Many farmers may be wondering how long to leave corn out in the field. We usually don't see a significant decrease in grain moisture after early to mid-November."

Thomison said that if the fall remains cool and moist, Ohio could be facing a repeat of 1992 corn harvest. Due to unfavorable weather conditions and cooler temperatures, some farmers didn't complete harvesting their corn until December and January the following year because the corn didn't dry down fast enough.

"Many corn agronomists look at 1992 as sort of a baseline year in terms of a corn crop that was slow to dry down," said Thomison. "If we have cool, wet conditions this fall, we could have conditions like we had in 1992. With a fair amount of corn planted late, some of the crop is going to stay wet for a while."

Despite the weather concerns slowing corn harvest, below-average temperatures during the growing season did their job in staving off pest and disease development.

"Overall, farmers have not discussed any major disease and pest problems, and what issues we have had have been low and localized," said Thomison.

In parts of the state, reports have surfaced on symptoms related to Anthracnose top dieback, a corn disease that kills the plant from the top down. Other minor problems include ear rot and late season Northern Corn Leaf Blight.

According to the Ohio Agricultural Statistics Service, corn is behind in development with only 46 percent of the crop mature and 4 percent harvested, compared to 79 percent and 14 percent, respectively, last year.

Candace Pollock
Peter Thomison