The EPA inspector general says it will assess the agency’s “management and oversight of [weed] resistance issues related to herbicide-tolerant genetically engineered crops.” In a letter to the EPA Office of Chemical Safety, the inspector general’s office listed three objectives:
–What steps did EPA take to delay herbicide resistance?
–What did EPA do to determine the risk to humans of weedkillers used against the so-called super weeds?
–How does EPA mitigate herbicide resistance?
The project should result in “a greater understanding of herbicide resistance which will lead to an enhancement of EPA’s herbicide resistance management and oversight,” says the letter.
Resistance has grown as a problem with the avid embrace by U.S. farmers of crops genetically engineered to withstand weedkillers. The issue is most pronounced with glyphosate, the most widely used weedkiller in the world, because many corn, soybean and cotton varieties are designed to work with it.
In a 2015 report, the USDA said farmers reported glyphosate-resistant weeds on 6 percent of corn land in 2010, and a decline in the effectiveness of glyphosate on 44 percent of soybean land in 2012. Corn farmers have inexpensive alternatives to glyphosate but glyphosate is the least-expensive, most-effective and less-damaging weedkiller available to soybean growers, according to the USDA.
Seed and ag-chemical companies are developing new GE strains that tolerate other weedkillers, often in combination with glyphosate. Farmers can rotate crops to prevent resistant weeds from establishing themselves, use mechanical cultivation to uproot weeds or plow fields to bury weed seeds. Herbicides are a popular way to control weeds in fields where farmers stir the soil as little as possible to reduce erosion.