Growers who forgo Bt traits in 2017 should be alert for the risk of European corn borer damage, which cropped up in non-GM corn fields in 2016. (Photo courtesy Purdue University)

ROCKVILLE, Md. (DTN) -- Kyle Kiefer was just a kid when he last witnessed the European corn borer at work. It was his job to clear the combine header of snapped and lodged corn plants, their stalks hollowed out by the tunneling pest.

The southern Illinois farmer isn't keen to return to those days. By the time he left school and started farming full time, Bt corn was controlling the pest so well, it slipped off his radar. Until this year, that is, when corn borer infested his non-GM corn acres and cost him up to a dozen bushels per acre in some fields where he farms near Belle Rive, Illinois. He estimated one non-Bt field was 20% lodged by harvest.

Lured in by reliable premiums ranging from 30 to 70 cents per bushel, Kiefer had devoted more and more acres to non-GM corn over the past five years. By the summer of 2016, non-GM hybrids accounted for up to 80% of his corn acres.

"There would be years that you would see European corn borer moths come and go, and there was always some light pressure but nothing extreme," he recalled. "This year, they just ate it up."

The damage was so discouraging that Kiefer is re-thinking his 2017 hybrid selection. "Originally, I was planning on booking all non-GMO corn, but I'll probably do just 25% now," he said.

The story is a familiar one to Burrus Hybrids agronomist Stephanie Porter this year. "Corn borer issues were huge," she said of her territory in Illinois. "We saw a lot of it in the non-GM corn but also in some areas in the north and south, where the damage was so bad you could look at a field and pick out the [non-Bt] refuge."

The rise in non-GM corn acres in the state is a possible culprit in these localized resurgences of this pest, entomologists told DTN.