Homegrown: Herbicide recalled for damaging trees

Linn County Master Gardener, Lisa Slattery, passed along the following information:

Imprelis herbicide (active ingredient aminocyclopyrachlor) is being recalled by DuPont because of damage and death to non-target trees.  Homeowners, and landscape and pest control professionals are also being warned not to compost grass clippings from Imprelis-treated lawns.

Imprelis was released by DuPont Professional Products into the turf market in October, 2010 as a broadleaf control.  The people that study turf at ISU said it was "very effective against a broad spectrum of really tough broadleaf weeds," including ground ivy (creeping Charlie), violets, and henbit.

In June, ISU Extension, other Midwestern state extensions and the EPA started receiving complaints of damage to conifer trees in lawns and on golf courses that had been treated with the herbicide.  The two most commonly damaged trees have been Norway Spruce and White Pine.    Many lawn companies were using Imprelis without realizing the potential damage to trees. 

Do not use grass clippings from areas treated with the herbicide for mulch or compost, or allow for collection to composting facilities.  In addition, these grass clippings should not be used as mulch around trees and gardens. 

The Environmental Protection Agency ordered DuPont to stop selling and distributing the herbicide a week after the company voluntarily suspended its sale on August 4.  The company plans a refund program.  At least five lawsuits have been filed in Minnesota over the herbicide.  DuPont states that it will soon be conducting a product return and refund program for the product.