Corn mold lurks in Illinois’ fields, threatening crop yields

By Julie Ingwersen 

CHCIAGO – A fungal disease called Diplodia ear rot is lurking in corn fields in portions of the Midwest, and crop experts and farmers fear lower yields and crop damage that could force growers to accept steep discounts on the cash market.

Diplodia, which causes a whitish mold between kernels, is common in corn but its emergence this year appears to be more severe than normal, particularly in central Illinois and western Ohio following rainy summer weather, agronomists in those states said.

The fungus has also emerged in parts of Missouri, Iowa and Indiana.

Farmers trying to market grain infected with Diplodia face penalties that can top $2 per bushel for the most severe damage. The discounts loom at a time when Chicago Board of Trade spot corn futures are hovering near $3.40 a bushel after approaching seven-year lows near $3 last month, below break-even for some growers.

“It’s more than a nuisance. It’s serious money,” said John Werries, who farms about 3,800 acres, mostly corn, in Chapin, in west-central Illinois. Werries said he was docked 80 cents per bushel on a portion of his corn this year that had 25 percent damage.

“This is my 52nd crop, and it’s the worst I’ve ever seen,” Werries said, adding that he had heard of loads of harvested corn with 80 percent damage elsewhere in his area.

Angie Peltier, a University of Illinois Extension educator based in Monmouth, Illinois, heard reports of Diplodia damage ranging from 2 to 50 percent between Henry and Madison counties.

Unlike some other corn molds, Diplodia is not poisonous. Grain handlers can manage it by blending damaged kernels with good-quality grain.

Greg Luce, a crop specialist with the University of Missouri Extension, said Diplodia was more widespread than usual in his state but not as severe as Illinois, where rich soil allows more farmers plant continuous corn, instead of rotating fields with soybeans.

A downside of planting corn-on-corn and reducing soil tillage is that the Diplodia fungus can survive the winter on corn residue. The next year’s crop is susceptible to infection, particularly if heavy rains hit in the weeks just after silking.

Peltier and others recommend that farmers who find the mold try to dry the harvested grain as quickly as possible. Moldy grain, Peltier noted, will not store well, especially as temperatures warm up in the spring.

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