Don’t compost this herbicide

Posted by Christine, June 24, 2011

Dan Sullivan of BioCycle reports:
Clopyralid, bifenthrin, aminopyralid. All of these agricultural chemicals have made headlines because they do not readily break down in compost. In some instances, they’ve been linked to major crop damage. In others, they’ve shut off commercial composters from some of their most lucrative markets. (See Table 1 for BioCycle coverage of these events, which started more than a decade ago.)

So when Wilmington, Delaware-based DuPont began aggressively marketing a new post-emergent broadleaf herbicide to landscapers, lawn maintenance professionals and turfgrass managers — under the name Imprelis and containing the active ingredient aminocyclopyrachlor — some organics recyclers became concerned. (An “active ingredient” is that part of a pesticide or herbicide product which performs the desired action, in this case killing off broad leaf weeds.) The red flag wasn’t so much that the active ingredient sounded to the ear very much like other chemicals that have plagued the industry in recent years (and is in fact quite similar chemically). It had more to do with an ominous label restriction, which states:

“Do not use grass clippings from treated areas for mulching or compost, or allow for collection to compost facilities. Grass clippings must either be left on the treated area, or, if allowed by local yard waste regulations, disposed of in the trash. Applicators must give verbal or written notice to property owners/property managers/residents not to use grass clippings from treated turf for mulch or compost.”