Herbicide Categories

Herbicides are placed into categories that are based on the unique impact they have on weeds and plants. Each type of herbicide has its own chemical structure that determines how it works, but similar herbicides are grouped together.

Selective and Non-Selective

• According to the University of Rhode Island's Landscape Horticulture Program, two types of herbicide classifications exist: selective and non-selective. Selective herbicides are herbicides that are intended to kill weeds without harming turfgrass. Non-selective herbicides destruct all living plants when applied in generous doses.

Contact and Systemic

• The effect herbicide has on a plant classifies the herbicide as having contact or systemic action. Contact action herbicides damage and kill the parts of where the herbicide comes into contact with the weed or plant. Systemic herbicide does not kill on contact. Rather, systemic herbicide is absorbed through the roots of the weed or plant and then transported throughout the tissues.

Considerations

• Herbicide solutions are made up of a combination of selective, non-selective, contact and systemic. For instance, phenoxy acid types of herbicides are selective and systemic, while bipyridylium types of herbicides are non-selective, contact chemicals. The application and type of weed to be treated will determine which type of combination the consumer should purchase.