Herbicides are a type of pesticide used to interfere with and/or disrupt the biochemical or physiological processes that are unique to plants. This interference typically decreases the growth, competitiveness, and/or seed production of unwanted plant species while providing opportunities for desired species to increase their population size and productivity. Herbicides, therefore, are a valuable tool for controlling unwanted plants on rangelands. When properly applied, herbicides can provide a window of opportunity for desired plants by removing or suppressing populations of weeds. The use of only herbicides to control weeds seldom results in successful long-term control. Once weed species are removed from a site, the area must be revegetated with desired species that can competitively exclude the potential weed species. Herbicides are most valuable when they are but one component of an integrated weed management plan that focuses on replacement of weeds with desired species, proper grazing management, and management actions that reduce the risk of new infestations.
Additional information is provided on the following pages for how herbicides work, their mode of action, their fate, their toxicity, and their successful use.