Herbicide Resistance, and Weeds, Are Spreading in the United States
Wednesday, July 13th, 2011
Herbicide resistance is growing. At least 21 weed species have now developed resistance to glyphosate, a systemic herbicide that has been effectively used to kill weeds and can be found in many commercial products. Some weeds are now developing resistance to alternative herbicides being used. New occurrences of resistance are being noted in varying weed species and locations, creating challenges for weed scientists.
Several articles in the current issue of the journal Weed Science focus on the issue of herbicide resistance. The articles highlight first reports of resistance. “The herbicide resistance issue is becoming serious,” the journal’s editor, William K. Vencill, said. “It is spreading out beyond where weed scientists have seen it before.”
Palmer amaranth is a common weed that competes with cotton, soybean, corn, grain sorghum, and peanut crops in the southern United States. A density of 10 of these weeds per row of cotton has been shown to reduce yields more than 50 percent. By 2010, 52 counties in the state of Georgia had infestations of glyphosate-resistant Palmer amaranth.