Herbicide resistance

Herbicide resistance is the inherited ability of a plant or other organism to survive a herbicide dose that would normally control it. It can arise through changes in the herbicide’s target or through other biological mechanisms.

Target-site resistance: Heritable resistance caused by changes to the biological target of a pesticide or other toxic agent. A target alteration can stop a herbicide from binding or disrupting its intended process.
Mutation: A change in an organism’s genetic material that can be inherited if it occurs in reproductive cells. Some mutations alter herbicide targets or other traits in ways that permit survival.
Herbicide rotation: A weed-management practice that alternates herbicides with different modes of action across treatments or seasons. Rotation can reduce repeated selection for resistance to one mode of action.
Herbicide resistance evolution: The population-level increase and spread of inherited traits that allow survival after herbicide exposure. Repeated treatment can shift weed populations toward resistant genotypes.
Glyphosate-resistant Palmer amaranth: Palmer amaranth populations that survive glyphosate through inherited resistance mechanisms. This prominent case includes resistance associated with amplification of the EPSPS gene.
Non-target-site resistance: Heritable resistance produced by mechanisms that reduce a toxic agent’s uptake, movement, or effect without altering its target. Metabolism, sequestration, or reduced uptake can protect plants even when the herbicide target remains unchanged.
Natural selection: A change in the frequency of inherited traits because individuals differ in survival or reproduction. Herbicide treatment favors resistant variants that leave more descendants.
Integrated weed management: A strategy combining chemical, cultural, mechanical, and biological methods to manage weeds. Diversifying control methods reduces reliance on herbicides that select for resistance.
Multiple herbicide resistance: Resistance in an organism to herbicides from multiple modes of action, arising through one or more mechanisms. Populations resistant to several herbicide groups have fewer chemical control options.
Herbicide-resistant Italian ryegrass: Italian ryegrass populations that survive herbicides because resistance traits have spread through the species. Its resistance to several herbicide groups illustrates the limits of repeated chemical control.

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