August 3, 2010

Western bean cutworm attacks Canada's cornfields

The western bean cutworm has made its way from corn-belt states in the US and is now slowly making its way through crops in Ontario and Quebec.

"This is the first year we're anticipating a significant problem," said Art Schaafsma, an expert in crop pest management at the University of Guelph in Guelph, Ontario. In just one year, there's been a proliferation not only in the insect's numbers but also in the number of regions where it's been found. "We've been getting significant trap catches. Last year it was more of a token catch," Schaafsma said.

Newly hatched larvae are a dull tan or pink colour with black heads. They feed on the plant's pollen, its silk and later, on its developing kernels. Its feeding can open up the ear to other pests, diseases and fungal infections. Farmers in Ontario and Quebec are being asked to scout for egg masses-pearly thumbtip-sized patches of eggs that turn purple before hatching-and for the larvae.

Schaafsma said the worst infestation he's seen so far was in one Ontario field. Eggs were found on 25% of corn plants, an invasion he estimates could cost the farmer 10%-15% of his crop yield. "It hits the farmer in the pocketbook," he said.

Still, Schaafsma said farmers shouldn't panic. He cautioned that Canada's bug problem is mild compared to the cutworm invasion in some US states.

Claude Parent, an agronomist with the Quebec Agriculture Ministry, agreed the contamination is-for now-on a relatively small scale. "We'll see some damage in a couple of fields. But if we look at how it spread elsewhere, it starts small. In all the US states we saw the population slowly increase," Parent said.

The bugs moved into Ontario in 2008 and spread to Quebec a year later. The pretty adult moth, with its star-and crescent-moon wing markings, had flown northeast from Nebraska, Arkansas and Colorado.