Threats to Organic Recycling Programs

Clopyralid in Compost and Mulch

Press Release:
DPR Announces Restrictions
to Protect Compost

The California Integrated Waste Management Board (CIWMB) and the composting industry recognize that clopyralid in compost poses a potential threat to the successful municipal waste recycling programs that have been implemented throughout California. The CIWMB, California Department of Pesticide Regulation (DPR), and other stakeholders have formed a workgroup to assess the scope of the issue and to propose mitigation measures.

• Background and Legislative Action
• Education and Outreach
• Compost Testing
• Resource Links
• Related Articles

Education and Outreach

Education and outreach are important in our collective efforts to mitigate the impact of clopyralid on the composting industry and statewide recycling efforts. As part of this effort, the CIWMB, California Department of Pesticide Regulation (DPR), and stakeholders are developing free brochures and fact sheets that can be downloaded and used for local educational efforts.

Free educational brochure on clopyralid and compost:

• Clopyralid and Compost: What We Know and What We're Learning

Compost Testing

The workgroup has collaborated with stakeholders to develop the following information as a guide for compost operators and others who are considering testing compost for clopyralid.

• Survey of Compost Samples for Presence of Clopyralid Herbicide--Final Report
  The CIWMB funded a study conducted by SDSU to test compost from facilities located throughout California for clopyralid residues.  Sampling occurred between fall 2003 and fall 2004.
• Sampling protocol. Provides a uniform approach to collecting and analyzing compost samples and includes the following forms:
  • Chain of custody form. United States Composting Council (Adobe PDF, 342 KB).
  • Compost sampling site information. Washington State Department of Agriculture (MS Word, 218 KB | Adobe PDF, 42 KB).
  • Compost feedstocks summary. Washington State Department of Agriculture (MS Word, 77 KB | Adobe PDF, 14 KB)
• Bioassays. Reviews the capacities of three bioassays for detecting clopyralid residues in compost.
• Study outline. Provides a format and guidelines for submitting data to DPR.

Resource Links

• California Assembly Bill 2356: California Assembly Bill on Clopyralid (AB 2356) (Adobe PDF)
• California Department of Pesticide Regulation
• US Composting Council: USCC Position Paper on Clopyralid and Composting October 2001
• Dow AgroSciences: Sensitive and Nonsensitive plant list
• Clopyralid in Compost: Washington State Department of Agriculture
• Oregon Department of Environmental Quality: Clopyralid Study (Adobe PDF)
• Clopyralid & Compost: Information for Gardeners  (Adobe PDF)

Related Articles

BioCycle Magazine--February 2003
(These articles made available courtesy of BioCycle Magazine. Subscription is required for online reading of complete issue. Purchase of back issues available.)

• Oregon Completes Clopyralid Study--Robert Rynk,  pg 28
• Quantifying Clopyralid--pg 30

Composting News--March 2003

• Herbicides in Compost: Potential effects on plants--April 2002
• Clopyralid degrades in compost, new research shows--March 2003
  (Subscription required for on-line reading of this article.) 

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Last updated: August 29, 2008