Clopyralid in Compost

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Clopyralid is the common name of a herbicide that kills broad-leaved weeds such as dandelions, clover, and thistle. Clopyralid contamination of yard debris compost emerged as a problem in Washington State in 2000 and 2001. Clopyralid has since been banned as a 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.

Information:

Questions and Answers for Gardeners and Farmers in Western Washington Revised Feb 2005 (pdf).
Clopyralid and compost: formulation and mowing effects on herbicide content of grass clippings. 13 Jan 04 (click title to request pdf e-copy)
Bioassay Test for Herbicide Residues in Compost Protocol for Gardeners and Researchers in Washington State (draft, pdf) 13 Jan 03.
Clopyralid in turfgrass clippings: formulation and mowing effects on dissipation (pdf file) 18 Mar 03.
Clopyralid Garden Demonstration Plots, 2002 (html for viewing with pdf for printing) revised 20 Dec 02.
Large Pot Greenhouse Trial with Clopyralid-Sensitive Garden Plants, 2002 (html and pdf)
WSDA Rule Restricting Use of Clopyralid in Washington (link to WSDA page).

Photos of clopyralid-damaged plants:

Organic Farming Systems and Nutrient Management