Reports suggest DuPont herbicide may damage trees

DuPont Professional Products has issued a warning to professional landscapers via their Web site to not use Imprelis, a DuPont-manufactured herbicide, near Norway spruce and white pine trees, amid concern from landscape professionals that the herbicide may damage the trees. The U.S. Environmental Protection Agency (EPA) has launched an investigation and is requiring DuPont to submit detailed information about the incidents by July 29.

A letter addressed to turf-management professionals and signed by Michael McDermott, global business leader for DuPont Professional Products, dated June 17, states “some of your industry colleagues have reported observing various unfavorable symptoms on certain species of trees and we wanted to keep you informed.”

The letter maintains that the majority of the reports involve Norway spruce and white pines, that in “most cases” Imprelis was not applied alone – rather, with a mixture of other herbicides – and that some reports “indicate there may have been errors in use rates, mixing practices and/or applications to exposed roots or the tree.”

The material safety data sheet for the product, under environmental information, states not to apply the product directly to water, or to areas where surface water is present, or to intertidal areas below the mean high water mark. It does not mention specific trees or plants that may have an adverse reaction.

It does state that it is not for use in or storage in or around the home. Human health hazards, if used improperly, include eye irritation with discomfort, pain, redness or visual impairment. It also states that the material is not likely to be hazardous through skin contact, but cleansing the skin after use is advisable.

Regarding overall human and animal hazards, it states that “none of the components present in this material at concentrations equal to or greater than 0.1 percent are listed by IARC, NTP or OSHA as a carcinogen.”

The ingredients are listed as potassium salt of aminocyclopyrachlor (25 percent) and inert ingredients (75 percent).

A “homeowner’s guide to Imprelis herbicide injury to landscape trees” produced by Michigan State University Extension states that Imprelis was developed and marketed to provide control of several difficult-to-control turf weeds, such as ground ivy and wild violet.

It states that homeowners, lawn service operators and others have “observed browning of shoots and needles twisting and shunting of roots, especially near tops of trees. … Unlike most conifer insect and disease problems, Imprelis damage occurs rapidly — usually within two or three weeks of application.”

The document says that as the damage reports began to come in from areas ranging from Kansas to Pennsylvania, DuPont released the June 17 cautioning the application near Norway spruce and white pine.

Delaware Department of Natural Resources and Environmental Control representatives said the department does not have oversight on the herbicide and does not itself use it anywhere. According to the Delaware Department of Agriculture, the product was registered for use in Delaware on Sept. 9, 2010, and the registration is valid for a two-year period.

Delaware Department of Agriculture representatives stated that they have not received any official pesticide complaints concerning the product, but that they have been contacted by a homeowners’ association from property that may have damage associated with it.

According to spokeswoman Anne Fitzgerald, the homeowner’s association was given the name of Dave Pyne, Delaware Department of Agriculture pesticide administrator, as a contact if they were interested in the pesticide section investigating the damage, but they have not received such a request.

U.S. Environmental Protection Agency representatives reported that the EPA has launched an immediate investigation to determine why a large number of conifer trees have been injured following use of E.I. DuPont de Nemours (DuPont’s) Imprelis herbicide.

“EPA is working closely with state officials and others to determine the cause of the damage to trees. In its evaluation, EPA is also investigating whether these incidents are the result of possible impurities in the manufacturing of Imprelis, product misuse, inadequate warnings and use directions on the product’s label, persistence in soil and plant material, uptake of the product through the root systems and absorbed into the plant tissue, environmental factors, potential run-off issues or other possible causes.

EPA is requiring DuPont to submit detailed information to the agency about the incidents by July 29 and has directed DuPont to determine the cause of the damage to the conifers.

Calls to DuPont about this story were not returned by Coastal Point press time.