The Minnesota fallout from Imprelis, a supposedly "green" lawn herbicide that is lethal to weeds but apparently can kill trees, too, has reached the courts.

At least five lawsuits have been filed in Minnesota, several of them seeking class action status. Minneapolis attorney Stephen Foley filed suit in U.S. District Court earlier this month on behalf of a Wayzata resident who claims that at least 10 spruce trees in his yard were damaged after Imprelis was applied to his front lawn.

"From what we've seen in the Upper Midwest where it was used a lot, the anecdotal stories are that there was wide damage," Foley said. "It was supposed to be the next best thing in herbicides, and then the damage reports came in."

DuPont voluntarily suspended sale of Imprelis on Aug. 4 and said it would begin a product recall and refund program by mid-August. Last Thursday, the Environmental Protection Agency (EPA) ordered DuPont to halt the sale, use and distribution of the chemical.

Imprelis was sold only to commercial applicators and was not available over the counter. But professionals embraced the product, which was heavily promoted as safe for the environment because it could be applied at a very low rate and was still effective against such difficult-to-kill weeds as creeping charlie.

The trouble began when, weeks after grass had been treated, evergreens began to show distorted and browning needles. In Minnesota, damage was reported to Black Hills spruce, Norway spruce, Colorado blue spruce and eastern white pines. Some trees apparently died. There have been reports that deciduous trees and some perennials have shown signs of herbicide damage, too.

Brian Horgan, associate professor of turfgrass management at the University of Minnesota, said he has never seen such a thing with an herbicide that apparently passed EPA review.

"The EPA requirements to get a label are extensive," he said. "I don't have an answer on that. ... I can tell you it's a great herbicide. This is very unfortunate because it has a lot of attributes."

The Minnesota Department of Agriculture surveyed 1,800 commercial applicators in July. About 25 of 100 firms that returned surveys said they had used Imprelis. Of those, perhaps five reported apparent damage to trees, bushes or perennials, said Allen Sommerfeld, communications coordinator for the agriculture department.

Because the survey was anonymous, it isn't clear how big those companies were or how many properties were affected. Many of the sites visited by University of Minnesota experts have been large tracts of land, such as those owned by golf courses and townhouse associations, but damage has been reported by homeowners, too.

Among them are Rich and Carolyn Nordstrom, who had their lawn in the east-metro suburb of Gem Lake treated for weeds this spring by Rainbow Lawn Care. Four evergreens planted about 20 years ago in the Nordstroms' front yard began to decline after Imprelis was sprayed on the lawn in May.

Rich Nordstrom said a Rainbow employee pointed out the stressed trees when he returned a few weeks later to care for the lawn. The four trees, which Nordstrom estimated stand 30 feet, have since turned totally brown. Six or seven other similar evergreens in the area appear unaffected.

"Rainbow told me that the product they used had killed my trees, and they were working with or talking to Dupont about what to do about this," Nordstrom said.

Rainbow told the Star Tribune in July that it would make things right with customers even though the company is not to blame for the damage. Nordstrom said Rainbow has been upfront about the damage and indicated it would replace the trees this fall or next spring.

Nordstrom said that will satisfy him.

"They were astounded that this product snuck through testing," Nordstrom said. "In my perfect world, I wish this wouldn't have happened, but we just move on."

Sommerfeld said the agriculture department is investigating and will coordinate any action with the EPA. Horgan said DuPont has hired field staff in Minnesota who are evaluating the severity of damage where complaints have come in.

Nationwide, at least 14 legal cases had been filed against DuPont as of last week, Foley said. He said a judicial panel on multi-district litigation appointed by the U.S. Supreme Court is expected to consider consolidation of the cases into a single case in September.

Mary Jane Smetanka • 612-673-7380