From knowledge to action: the importance of characterizing herbicide resistance mechanisms for implementing management strategies

Herbicide resistance remains one of the most intensively studied areas in weed science because of its direct consequences for crop yield and production costs. Although major advances have been made in identifying resistance mechanisms, the translation of these insights into technologies that can slow the evolution of resistance remains limited. This review synthesizes current knowledge of herbicide resistance with a strong emphasis on mechanism-informed management. We provide a detailed analysis of target-site resistance mutations across major herbicide modes of action, highlighting mutation- and species-specific cross-resistance patterns that enable rational herbicide selection beyond blanket mode-of-action exclusion. We also comprehensively address non-target-site resistance with attention to environmental modulation of resistance expression, and a first unified overview of all metabolic genes underlying herbicide resistance. Finally, we discuss a forward-looking framework linking molecular diagnostics and genomics to field-level resistance management and stewardship. Understanding the mechanisms of resistance can reveal potential weaknesses.