Imprelis herbicide banned from sale, use in Indiana

September 19, 2011

WEST LAFAYETTE, Ind. – The Office of Indiana State Chemist has banned the sale, distribution and use of Imprelis in the state after investigating hundreds of complaints and finding that the herbicide was responsible for damage to trees and ornamental plants.

The office this week is notifying lawn care companies and other professional users of the herbicide made by DuPont that the product's registration in Indiana has been canceled, said Dave Scott, pesticide administrator with the state chemist's office, based at Purdue University.

"The only thing they are permitted to do with it is return it to DuPont for disposal," Scott said. "We have been advised by DuPont that they will be reimbursed for it whether it is in a closed container or an open container. There is no reason to hold onto it."

Indiana's action follows a U.S. Environmental Protection Agency order in August requiring DuPont to stop selling and distributing it. The step Indiana took was necessary to prohibit others from selling and using it in the state, Scott said.

"Imprelis is already out there, so this is a way to plug any holes because the EPA order technically applied only to DuPont," Scott said. "Now, Imprelis cannot be sold, distributed or used by anyone in Indiana."

The office had notified DuPont in August that it intended to cancel the registration, and the company was given until Sept. 15 to appeal. Instead, the company voluntarily asked the state chemist to cancel it, Scott said.

DuPont and the EPA are working out procedures for recall of the chemical, Scott said.

Imprelis, with the active ingredient aminocyclopyrachlor, was approved by the EPA and registered in Indiana late last year for use by lawn care companies and other professionals. It was not available through retail sale.

The herbicide was intended to control a variety of broadleaf weeds such as ground ivy (creeping Charlie) and wild violet on lawns, golf courses, parks, cemeteries, athletic fields and sod farms.

Extension services in more than 20 states from Kansas to Pennsylvania reported cases of damage to trees and ornamentals possibly associated with Imprelis.

Imprelis became the target of complaints in Indiana in the spring from lawn care providers and their customers who suspected it was damaging trees – mainly evergreens –and ornamental plants near where it was applied. The state chemist in July urged lawn care providers not to use it until experts determined whether it was causing the damage. Since then, investigations have determined that Imprelis was the cause, Scott said.

The state chemist's office has investigated nearly 400 complaints about Imprelis since June, the most complaints about any herbicide Scott has seen in his 30 years at the state chemist's office.  He said the office is finalizing the investigations and that property owners and applicators will receive a copy of the investigation report for their property.

DuPont earlier this month sent notices to users of Imprelis specifying how it would handle damage claims, Scott said. Those wanting to submit a claim must do so by Nov. 30.

"For anybody who calls in now with a complaint about Imprelis, we're encouraging them to contact DuPont to make sure they get their claims processed by the cutoff date," Scott said.

More information about Imprelis, including how to submit a claim to DuPont, is available on the state chemist's website at

Writer: Keith Robinson, 765-494-2722,

Source: Dave Scott, 765-494-1593,

Ag Communications: (765) 494-2722;
Keith Robinson,
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