Clopyralid

Clopyralid is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers. It is in the picolinic acid family of herbicides, which also includes aminopyralid, picloram, triclopyr, and several less common herbicides.

Clopyralid is known for its ability to persist in dead plants and compost, and therein to damage certain crops, particularly potatoes and tomatoes, which are very sensitive to it. It is also known to be toxic to dogs and aquatic organisms.

Chemistry

Clopyralid is a member of the pyridine group of herbicides. It is a systemic herbicide that is absorbed by the leaves and roots and translocated throughout the plant. The chemical works by mimicking the plant hormone auxin, which results in uncontrolled growth and eventually death in susceptible plants.

Uses

Clopyralid is used in agriculture, forestry, on lawns, on roadsides, and other places where control of clover, thistles, and other broadleaf weeds is desired. It is often used in a mix with other herbicides to increase the spectrum of weeds controlled.

Environmental Impact

Clopyralid is known to persist in the environment and can cause damage to certain crops if it is present in compost or mulch used on those crops. It is also toxic to dogs and aquatic organisms.

Health Effects

Exposure to clopyralid can cause eye irritation, skin irritation, and if ingested, can cause nausea, vomiting, and diarrhea. Long-term exposure can lead to more serious health effects.

Regulation

In the United States, clopyralid is regulated by the Environmental Protection Agency (EPA) and is classified as a General Use Pesticide (GUP).

See Also

• Herbicide
• Weed
• Pesticide
• Environmental Protection Agency