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Bt resistance concerns in more IL counties
Three more counties in Illinois have been confirmed with cases of Bt corn resistance by western corn rootworm bringing the total to five counties. University of Illinois entomologist Mike Gray says resistance has been found in McDonough and Mercer counties in northwestern Illinois and in central Illinois’ Sangamon County to the Cry-3-B-b-1 protein. He tells Brownfield Ag News, “It’s the protein that first entered the marketplace back in 2003. And, in some Bt hybrids, you know, we’re hearing similar reports in other states such as Iowa, Nebraska and Minnesota.”
Gray points out there are only four Bt rootworm proteins in the marketplace, “There’s concern that there may be some cross-resistance to that particular protein from one of the other routine proteins as well. That was just recently reported by a researcher at Iowa State University, Aaron Gassman.”
Gray says there are no effective rescue treatments for corn rootworm. Selecting the right seed in the fall, he tells Brownfield, is key and scouting for the adult rootworm in the summer is vital, “You know, get an idea how many beetles are out there in those corn and soybean fields and that helps you make some kind of decision regarding – what is the likely pressure, how much damage might I expect for the following season? That’s always a good idea.” Gray says they’ve found that crop rotation is not a guarantee for preventing corn rootworm.
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