Herbicide mechanisms of action and resistance

Authors: DAYAN, FRANCK - Colorado State University; BARKER, ABIGAIL - Colorado State University; BOUGH, RAVEN - Colorado State University; ORTIZ, MIRELLA - Colorado State University; TAKANO, HUDSON - Colorado State University; Duke, Stephen

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/5/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Weed management in most agroecosystems relies almost entirely on synthetic herbicides because of their high efficacy and relatively low cost compared to other weed control technologies. By volume, herbicides are the most abundantly used category of pesticides applied in agriculture. Although several hundreds of synthetic herbicides are commercialized, the activity of these molecules is limited to inhibition of only about twenty known molecular target sites. These include processes associated with photosynthesis, the biosynthesis of molecular building blocks or their assembly into macromolecules, and disruption of growth by altering hormonal homeostasis or of regulation of protein activity. Because herbicides are such potent inhibitors of specific plant enzymes and protein functions normally absent in animals, these molecules normally have with little or no toxicity towards non-target organisms at exposure doses, especially mammals. This updated chapter includes new relevant information on the mode of action of various herbicides. We also mention the various target-site and non-target-sites mechanisms of herbicide resistance that have evolved in weeds since the publication of the previous chapter.

Technical Abstract: Weed management in most agroecosystems relies almost entirely on synthetic herbicides because of their high efficacy and relatively low cost compared to other weed control technologies. By volume, herbicides are the most abundantly used category of pesticides applied in agriculture. Although several hundreds of synthetic herbicides are commercialized, the activity of these molecules is limited to inhibition of only about twenty known molecular target sites. These include processes associated with photosynthesis, the biosynthesis of molecular building blocks or their assembly into macromolecules, and disruption of growth by altering hormonal homeostasis or of regulation of protein activity. Because herbicides are such potent inhibitors of specific plant enzymes and protein functions normally absent in animals, these molecules normally have with little or no toxicity towards non-target organisms at exposure doses, especially mammals. This updated chapter includes new relevant information on the mode of action of various herbicides. We also mention the various target-site and non-target-sites mechanisms of herbicide resistance that have evolved in weeds since the publication of the previous chapter.