New crop traits that allow use of older herbicides may help farmers manage resistant weeds
Farmers, plant geneticists, chemists, and agronomists recently have been engaged in an arms race against weeds, particularly weeds that have evolved resistance to the common herbicide glyphosate. A second generation of herbicide-tolerant crops has been developed to battle resistant weeds, but they have sparked concerns about overreliance on chemical controls.
Introduced in the 1980s, glyphosate has been the best-selling herbicide since 2001. Monsanto, which markets glyphosate as Roundup, introduced crops engineered to be tolerant of glyphosate in the late 1990s, and farmers now plant Roundup Ready herbicide-tolerant corn, soybeans, and cotton on the majority of cultivated acres in the U.S. Thanks to the popularity of the firm’s Roundup Ready trait, last year 94% of soybean acres were herbicide-tolerant, as was 73% of cotton acreage and 72% of corn acreage, according to the Department of Agriculture.
Farmers liked glyphosate because it vastly simplified weed control. But it also led to the emergence of resistant weeds that are increasingly hard to kill.