en.Wedoany.com Report on Mar 27th, Researchers in Minnesota have confirmed the first population of glufosinate-resistant waterhemp, the second documented case in the United States, following a previous discovery in Illinois. This finding heightens concerns about the efficacy of herbicide programs, as glufosinate was one of the last reliable tools for controlling multiple-resistant waterhemp.

Researchers from the University of Minnesota Extension identified the glufosinate-resistant waterhemp based on a farmer's report of control failure in Dodge County in 2023. Greenhouse and field tests showed the waterhemp survived and regrew at standard application rates. The researchers stated, "There may be other glufosinate-resistant waterhemp populations that have not yet been identified." In the trials, glufosinate provided only about 60% control, which is typically insufficient for soybean weed management.

As resistance to other herbicide classes spreads, glufosinate has become a common tool in soybean systems. The Minnesota study showed that at four sites, waterhemp populations were resistant to six herbicide sites of action, making glufosinate the only effective postemergence option. Researchers warn that the industry may be approaching a tipping point, with some waterhemp populations having no effective postemergence herbicides available in soybeans. Surveys also indicate that waterhemp resistance is accelerating across the region, with declining control from classes like 2,4-D, atrazine, and HPPD inhibitors.

Earlier research indicates this resistance stems from non-target site mechanisms, rather than target site mutations. Metabolic resistance allows waterhemp to survive multiple herbicide classes, increasing management complexity. Researchers emphasize that herbicide stewardship and diversification measures, such as using cover crops like cereal rye, are crucial for slowing resistance and preserving remaining options.