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University of Illinois Documents Waterhemp Resistant to Another Class of Herbicides

Scientists at the University of Illinois have documented waterhemp as the first non-grass plant that is resistant to Group 15s herbicides. Waterhemp is a common and problematic weed in corn and soybean fields in the Midwest. A news story from University of Illinois explains that herbicides are divided into 16 different Mode of Action (MOA) classes. Historically, nine classes of herbicide worked on waterhemp, but the plant has developed resistance to seven of those classes. “In some areas, we’re one or two MOAs away from completely losing chemical control of waterhemp and other multiple-herbicide-resistant weeds,” says Adam Davis, head of the Department of Crop Sciences at Illinois and co-author on the study. In this study, the waterhemp showed resistance even when herbicide was applied at four times the label rate.