US EPA Urged to Limit Herbicide Use on GE Crops

Overuse of the herbicide glyphosate has resulted in the evolution of resistant weeds, threatening the long-term sustainability of corn, soybeans, canola, and other crops that have been genetically engineered to tolerate glyphosate. The nonprofit Center for Science in the Public Interest is calling on the US Environmental Protection Agency, which regulates the herbicides sprayed on those engineered crops, to limit use of glyphosate and adopt other measures to slow the spread of resistant weeds.

Farmers planted 170 million acres of genetically engineered crops in 2012. About 154 million acres of that was planted with crops that can tolerate herbicides, the vast majority to Roundup or other brands of glyphosate, which is a relatively benign chemical. But since farmers are increasingly dealing with weeds that aren't killed by glyphosate, they also are applying more harmful herbicides—negating much of the technology's benefit.

In a letter to the US EPA's Office of Chemical Safety and Pollution Prevention, CSPI says that the agency should limit farmers’ use of glyphosate, especially in geographic areas where resistant weeds are becoming a problem. Such a limit might forbid farmers from applying glyphosate in the same field two years in a row. The agency should also encourage farmers to adopt resistant-weed management plans and reduce glyphosate use through integrated weed management, according to CSPI. Non-chemical weed management techniques such as crop rotation and cover crops will continue to be underutilized without US EPA involvement, the group says.

"It's not in farmers' or the biotechnology industry's short-term financial interest to adopt these measures on their own, so the US EPA should use its authority to protect glyphosate's effectiveness," said CSPI biotechnology director Gregory Jaffe. "Otherwise, the industry might squander this very valuable benefit of genetically engineered crops."

CSPI's letter points out that the US EPA instituted similar requirements to protect the effectiveness of crops engineered to produce a natural insecticide, Bt. CSPI also urged the US EPA to take steps to reduce the likelihood of weeds developing resistance to other major herbicides, such as 2,4-D and dicamba. That's because, according to CSPI, in 2013 the U.S. Department of Agriculture likely will approve new genetically engineered crops designed to tolerate application of those chemicals, and farmers may begin planting them by 2014.