Keith Good: Corn Rootworm Resistance – EPA Proposes Regulatory Measures

Bt corn-on-corn is not good resistance management

Jacob Bunge reported in today’s Wall Street Journal that, “U.S. regulators for the first time are proposing limits on the planting of some genetically engineered corn to combat a voracious pest that has evolved to resist the bug-killing crops, a potential blow to makers of biotech seeds.

“The measures proposed by the Environmental Protection Agency represent a bold step to thwart the corn rootworm, a bug that ranks among the most expensive crop threats to U.S. corn farmers.

“The plan is aimed at widely grown corn varieties sold by Monsanto Co. , the first to sell rootworm-resistant corn, and rival seed makers including DuPont Co. and Dow Chemical Co. Such corn seeds have been genetically modified to secrete proteins that are toxic to destructive insects, but safe for human consumption, helping to reduce farmers’ reliance on synthetic pesticides.”

Mr. Bunge pointed out that, “The EPA’s proposal would require seed companies to limit some Midwestern farmers’ practice of sowing fields with corn year after year in areas harboring resistant rootworms, whose cream-colored larvae gnaw on corn roots and stunt plants’ growth. The EPA is concerned that if the resistance continues, it will lead farmers to use more synthetic chemicals to thwart the bug, creating environmental risks.

“Representatives of the biotech-seed industry have criticized some parts of the proposal, which was released in January and is subject to a public-comment period until March 16, after which the EPA will finalize any new requirements.

“The agency is taking a tougher stance because the industry’s efforts haven’t done enough to stem the spread of pesticide-resistant rootworms in the Midwest, officials said.”

The Journal article added that, “Among its proposed changes, the EPA would require makers of rootworm-resistant corn to curb some repeated corn planting in areas badly afflicted by the pest. In portions of Iowa, Illinois, Nebraska and some surrounding states–what EPA officials called the rootworm ‘red zone’–the agency is pushing for about 35% of corn fields to be planted with another crop, such as soybeans, after two consecutive years of planting of rootworm-resistant biotech corn. Other high-risk fields should be planted with newer corn that can produce multiple types of bug-killing proteins, according to the EPA proposal.”


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