Climate Change Complicates Herbicide Effectiveness in Corn Belt Agriculture

**Weed scientists have discovered that changing climate conditions are reducing the effectiveness of post-emergence (POST) herbicides in the U.S. Corn Belt.** Analyzing a 30-year dataset, the study highlights how variable weather conditions, notably air temperatures below 66°F or above 77°F, and certain precipitation patterns, impact the performance of fomesafen, glyphosate, and mesotrione. _Warm conditions_ before application can accelerate weed growth, while _hot periods_ afterward may neutralize the herbicide's efficacy. Conversely, _cold temperatures_ slow down the metabolism and internal movement of herbicides within the plant. _Dry spells_ thickening the waxy cuticle of leaves and _excess rain_ washing off herbicides also affect performance. Furthermore, a combination of glyphosate and fomesafen showed more robust weed control but was not foolproof. **The researchers suggest integrating soil-applied residual herbicides and non-chemical methods.** They caution that, with climate change accelerating weed adaptation, new management tools are crucial. The findings underscore the need for continued research and innovation to prevent future failures in weed control, which could jeopardize global food security.