'Superweeds' linked to rising herbicide use in GM crops, study finds

'Superweeds' linked to rising herbicide use in GM crops, study finds

ScienceDaily (Oct. 2, 2012) — A study published this week by Washington State University research professor Charles Benbrook finds that the use of herbicides in the production of three genetically modified herbicide-tolerant crops -- cotton, soybeans and corn -- has actually increased.

This counterintuitive finding is based on an exhaustive analysis of publicly available data from the U.S. Department of Agriculture's National Agriculture Statistics Service. Benbrook's analysis is the first peer-reviewed, published estimate of the impacts of genetically engineered (GE) herbicide-resistant (HT) crops on pesticide use.
In the study, which appeared in the open-access, peer-reviewed journal Environmental Sciences Europe, Benbrook writes that the emergence and spread of glyphosate-resistant weeds is strongly correlated with the upward trajectory in herbicide use. Marketed as Roundup and other trade names, glyphosate is a broad-spectrum systemic herbicide used to kill weeds. Approximately 95 percent of soybean and cotton acres, and more than 85 percent of corn, are planted to varieties genetically modified to be herbicide resistant.
"Resistant weeds have become a major problem for many farmers reliant on GE crops, and they are now driving up the volume of herbicide needed each year by about 25 percent," Benbrook said.
The annual increase in the herbicides required to deal with tougher-to-control weeds on cropland planted to GE cultivars has grown from 1.5 million pounds in 1999 to about 90 million pounds in 2011.