If you’re dealing with herbicide-resistant weeds, you may want to consider adding cover crops to your weed-management strategy. According to study from the University of Tennessee, adding cover crops can help reduce the prevalence of Palmer amaranth in cotton fields and address the growing problem of glyphosate-resistant weeds. “Results suggest that selecting a cereal plus a legume cover crop mixture will add to early-season Palmer amaranth suppression when compared with a single cover crop species. This reduction in Palmer amaranth emergence could have a very positive effect in reducing selection pressure for herbicide resistance,” the authors wrote in their paper, which was published in Weed Technology. “Research has found that cover crops may reduce weed biomass, thereby reducing seed production and limiting the number of plants that emerge, which lowers the probability of selecting for new herbicide resistance development.”
Researchers looked at a variety of cover crops--cereal rye, crimson clover, hairy vetch, winter wheat, and combinations of one grass plus one legume—to see what varieties were the most effective in weed control. The winner? Cereal rye and wheat, according to the paper, which noted that crimson clover and hairy vetch treatments were the least effective at controlling Palmer amaranth. Still, even growers that plant cereal rye and wheat will want to keep their herbicides handy to treat their fields as needed. “The combination of high-residue cover crop and PRE herbicides can be part of an effective glyphosate-resistant Palmer amaranth management strategy, but additional means of control are necessary for consistent control later in the cotton growing season,” the researchers concluded. Have you used cover crops to manage weeds? Let us know in the comments.