By Ian Berry
New tests confirm that damage last year to some corn fields in western Illinois was caused by rootworms that have developed resistance to a Monsanto Co. (MON) genetically modified trait, a University of Illinois researcher said.
Illinois becomes the second state where researchers say they have confirmed rootworm resistance to the gene, which makes a protein that kills the voracious bug. Last year an Iowa State researcher announced resistance in that state, a finding that fueled concern among farmers and agronomists about overuse of genetically modified crops causing the development of superbugs.
University of Illinois entomologist Mike Gray, who announced the findings at a Thursday presentation, said they reinforce what Iowa State entomologist Aaron Gassmann reported last year in nearby counties in northeast Iowa. Gray had reported the Illinois rootworm damage last year, leading to the tests.
"The results are very similar to what came out of [Dr. Gassmann's] labs," Dr. Gray said.
In both cases, Dr. Gray said, the damage resulted in fields where corn was grown continuously for multiple years, which increases the opportunities for the rootworm to develop resistance to the trait. Farmers typically rotate a field from corn to soybeans the following year, but recently more have planted corn year-after-year, spurred by the high price of the crop.
Corn plants that fall prey to the rootworm are weakened by the pest and can ultimately fall over during high winds.
The widespread prevalence of rootworm resistant corn, he added, left farmers without access to corn that doesn't include the gene. A Monsanto official disputed that assertion.
Monsanto is not conceding that rootworm resistance has been confirmed, but Ty Vaughn, the company's corn product management lead, said the company is treating all the reported cases as "suspected resistance."
The company has added a program of recommendations for farmers who unexpectedly suffered rootworm damage last year, and that the results show farmers can easily manage the problem.
The top recommendations, Vaughn said in an interview, are for farmers to include soybeans in their crop rotation instead of planting corn every year, and to plant SmartStax, another Monsanto corn seed that includes two different traits that give the plant rootworm resistance. Soil insecticide use is the "distant third" recommendation, he said.
"They get hooked on the corn-on-corn train, and it's really hard to break free from that," Vaughn said.
In addition to university researchers, rootworm resistance has also drawn the attention of the Environmental Protection Agency, which last fall told Monsanto in a memo that its existing monitoring program was "ineffective" and said it wanted Monsanto to begin surveying fields at earlier signs of insect damage than it does now.
Write to Ian Berry at email@example.com
Corrections & Amplifications
This article was corrected at 3:45 p.m. EDT to correct a quotation in the eighth paragraph. Mr. Vaughn said the company is treating all the reported cases as "suspected," not "expected," resistance.
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