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Washington State University - Puyallup Organic Farming Systems and Nutrient Management

Clopyralid in Compost


Clopyralid is the common name of a long lived herbicide that kills broad-leaved weeds such as dandelions, clover, and thistle. Contamination of yard debris compost with clopyralid emerged as a problem in Washington State in 2000 and 2001 when it survived the composting process and affected garden plants grown in the compost. Clopyralid has since been banned as a home lawn herbicide, removing the risk of contamination of yard debris compost. Because clopyralid is still registered for use on grass hay and some grain crops, the risk of contamination of some animal manures with clopyralid remains.


♣ Clopyralid in Compost: Questions and Answers for Gardeners and Farmers in Western Washington (PDF-Online), Cogger, C. 2005. Online Brief.

♣ Clopyralid and Compost: Formulation and Mowing Effects on Herbicide Content of Grass Clippings (Request pdf e-copy). Miltner, E., A. Bary, and C. Cogger. 2004. Compost Science & Utilization. 11(4):289-299.

Bioassay Test for Herbicide Residues in Compost: Protocol for Gardeners and Researchers in Washington State (PDF-Online, draft), 2002. Wash. St. Univ., Wash. Dept. Ecology.

♣ Clopyralid in Turfgrass Clippings: Formulation and Mowing Effects on Dissipation (PDF-Online), Miltner, E., A. Bary, and C. Cogger. 2002. Poster Presented at ASA Annual Meeting, Indianapolis, IN, Nov 2002. Reformatted for printout.

♣ Clopyralid: Garden Demonstration Plots (PDF-Online), Cogger, C., A. Bary, and E. Myhre. 2002. WSU Online Research Brief.

♣ Large Pot Greenhouse Trial with Clopyralid-Sensitive Garden Plants (PDF-Online, Final Report). Bary, A., E. Myhre, and C. Cogger. 2002. WSU Online Research Brief.

♣ WSDA Rule Restricting Use of Clopyralid in Washington (see specifically ♣ WAC16-228-1235, ♣ WAC16-228-12351, ♣ WAC16-228-12352, ♣ 16-228-1237, ♣ 16-228-12371 (♣ link to WSDA main website).