Genetically-engineered crops have created more herbicide-resistant weeds—or "superweeds"— and increased, rather than decreased, the use of pesticides and herbicides such as Roundup, according to a new study published in Environmental Sciences Europe.
While the genetically-engineered crops, such as corn, soybeans and cotton, have been commercially successful, the use of technology led to a 527 million pound increase in the use of herbicide in the United States between 1996 and 2011, according to the study.
"Impacts of genetically engineered crops on pesticide use in the U.S.—the first sixteen years," and overall pesticide use increased by an estimated 404 million pounds, or about 7 percent, study author Charles M. Benbrook said.
Glyphosate, marketed as Roundup, is one of several broad-spectrum herbicides used to kill weeds, according to the online journal Phys.org. Approximately 95 percent of soybean and cotton acres, and over 85 percent of corn, are genetically modified to be herbicide resistant, according to Phys.org.
The study concluded that over-reliance on herbicides and the emergence of "supersedes" caused farmers to increase their use of herbicides and add new forms of them.
Weeds with natural resistance then spread quickly when farmers relied too heavily on a single weedkiller, the BBC reported.
"There are now two-dozen weeds resistant to glyphosate … and many of these are spreading rapidly," an analysis of the study by Washington State University said. "Millions of acres are infested with more than one glyphosate-resistant weed. The presence of resistant weeds drives up herbicide use by 25% to 50%, and increases farmer-weed control costs by at least as much."
One solution to resistance could be a new type of genetically modified crop that uses a weedkiller once used in the defoliant Agent Orange, which was used during the Vietnam War, according to the BBC.