What can I do if there are persistent herbicides in my compost and manure?
Answer: Most agricultural herbicides break down quickly in the environment. There are a few exceptions, however, particularly Clopyralid and Picloram, which have shown up in compost residues throughout the country. Clopyralid is a long-lasting herbicide that is commonly used on turf and has surfaced in municipal composting facilities that compost lawn and leaf residues and Picloram is used to control broad leafed weeds such as Canadian Thistle. It is currently banned for use on lawns in Washington State, and agricultural producers are required to have a pesticide applicators license to spray it.The Woods End Laboratory is an alternative soil and compost testing lab in Maine. Woods End has developed some of the most accurate bioassays for revealing herbicide residue effects. Their tests are effective to the lowest levels attainable and protects from misinterpretation of other harmful effects, such as high salt content in compost. For more information, contact: Woods End Laboratories, Inc.PO Box 297, Mt Vernon, ME 04352207-293-2457 email@example.comOn the west coast, Environmental Analysis Inc. (EMA) in Woodland, California, conducts residue testing on both plants and soil. To learn more, contact:Environmental Micro Analysis Inc.40N East Street, Suite BWoodland, CA 95776530-666-6890www.emalab.com/To find additional testing laboratories, check out ATTRA’s Alternative Soil Testing Laboratories database, available at https://attra.ncat.org/attra-pub/soil_testing/. This database identifies a range of soil testing labs and supplies that support the special analytical needs of farmers using organic or sustainable production methods. It is searchable by state, product category, or keyword.It is essential that you know the limitations of this testing, though. There are limits on the feasibility of testing for some types of herbicides. ATTRA recommends that you call the laboratories of your choice to ask the following questions along with the symptoms that might explain your situation. ? Will the test tell me what I want to know?? What kind of sample do I send?? Cost? Often these tests can be quite expensive ($70 to $150).? Is the test actually necessary or useful?? Can the lab actually do the test needed?Information on Cloropyralid symptoms is available in the pdf document link here: www.puyallup.wsu.edu/soilmgmt/Pubs/BeanClopyralidDamage.pdf.More information on herbicide residue in general in compost is available from the BioCycle article “Prevalence and Fate of Clopyralid in Compost,” available at www.puyallup.wsu.edu/soilmgmt/Pubs/Paper_ClopyralidQandAv10.pdf.Another fact sheet from Ohio State Extension has a good overview of herbicide in compost and straw. It is available at http://ohioline.osu.edu/aex-fact/0714.html.A sign of herbicide damage is when plants to which you applied compost exhibit curled and burned leaves. Certain plants are particularly susceptible to herbicide damage, however, including peppers, peas, tomatoes, red clover, and cucumbers. If only these plants are damaged, then most likely herbicide residue is the culprit.When you source compost and straw for mulch in the future, be sure to ask if the animals have been fed hay that has had Cloropyralid applied.