Spruce TreeSince 2008, we have reported on the dangers of pyralid herbicides (including Milestone, Forefront and other trade names) which turn grass clippings, manure, or hay into killer compost or mulch that can ruin gardens and farmland for years. Despite ample evidence that these deadly herbicides are damaging fields and gardens, and despite our calls for the companies and the Environmental Protection Agency (EPA) to solve this problem, we were angered to learn that another deadly pyralid herbicide, Imprelis (aminocyclopyrachlor), was widely sold in the spring of 2011, following its approval by the EPA in August 2010.

Invented by a team of scientists at DuPont, aminocyclopyrachlor is marketed to control weeds in cool-season lawn grasses, especially bluegrass (it is not generally sold in warmer climates, where bluegrass lawns are rare).
 DuPont never denied that Imprelis-treated lawns would create killer compost. Lost in a 19-item bulleted list on Page 7 of the 9-page Imprelis label, we found this language:
 “Do not use grass clippings from treated areas for mulching or compost, or allow for collection to composting 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 owner/property managers/residents to not use grass clippings from treated turf for mulch or compost.”

Come on, people! How likely is it that users will even read this 9-page label, let alone give notice to others “to not use clippings for mulch or compost”? Despite ample evidence of the severe problems these herbicides are causing, the EPA continues to allow chemical companies to sell them and hide behind “the label is the law” by putting unrealistic instructions and a liability release on the product labels.

Now for more really bad news. Following its first spring of use, Imprelis has been implicated in the injury and/or death of thousands of Norway spruce and white pine trees throughout the Midwest. Conifers that are growing in or near grassy areas treated with Imprelis, and are showing new growth that is brown and twisted, have been reported in Pennsylvania, Minnesota, Iowa, Delaware , Indiana, Nebraska , Wisconsin, and several other states. Michigan State has published an advisory on What to Do With Imprelis-Affected Trees, and Purdue University in Indiana has set up channels for Imprelis related herbicide complaints, as have Nebraska and Wisconsin.

Meanwhile, DuPont has sent this letter to turf management professionals, asking for help as they “continue their work.” The letter says “to be careful that no spray treatment, drift or runoff occurs that could make contact with trees or shrubs … And stay well away from the root zone of trees and shrubs” when applying Imprelis. It also says to “Consult a certified arborist if you are uncertain about the root zone of specific tree species.” Tree roots often spread three times as wide as the branches, so few properties could be treated with this herbicide in keeping with these guidelines.

On July 5, 2011, DuPont issued a new advisory for handling trees affected by aminocyclopyrachlor. Their justification for selling this deeply flawed, under-tested product is that it was approved by the EPA. We believe DuPont should not have to be forced by the government to do the right thing. We are calling on DuPont to cease selling Imprelis immediately, before more damage is done. What will happen when the chipped wood from already injured trees ends up at compost facilities? As Michigan State’s Bert Cregg commented this week, “Might be good to fasten your seatbelts, this could be a bumpy ride.”

The world is running out of oil, and that means we are running out of chemical fertilizer, and that means we MUST expand our systems to capture and recycle organic materials if we hope to maintain the fertility of our soils. Herbicides that can enter and persist for years in compost and soil should be banished from the planet.
Maybe somebody should treat the White House lawn with Imprelis, and when their historic tree collection starts dying, Washington will take action.

Photo: Purdue University Extension

Related Reading:
Oct 2008: Watch Out For Killer Compost
July 2009: Milestone Herbicide Creates Killer Compost
September 2009: Contaminated Compost — Coming Soon to a Store Near You