INDIANAPOLIS -- Several Indiana golf courses are teeing off against DuPont, which manufactures a weed killer some claim is killing trees.

6News first reported on Imprelis last month. DuPont touts the chemical as the most advanced weed killer to hit the market in four decades, 6News' Chance Walser reported.

A lawsuit seeking class-action status filed on Monday includes several Indiana golf courses and homeowners, claiming the herbicide is killing evergreen trees and that DuPont failed to conduct proper testing and didn't put warning labels on the product.

The company said last month that more than 400 tests were performed on the chemical before it was released as a product.

The greens are green at Ironwood Golf Club, but some of the resident trees are brown and appear to be dying.

At Winding Ridge Golf Course in Lawrence, there are 130 dead or dying evergreens, and no one is certain why.

Lawn care experts who have used the product said brown evergreens with shriveled branches are a tell-tale sign of Imprelis.

"This is not just affecting Indiana, but people in Michigan, Pennsylvania, Delaware, all the way into Minnesota," said Mario Massillamany, an attorney for the plaintiffs.

DuPont said it has received several complaints and has been conducting on-site investigations across the country.

"DuPont is committed to proper stewardship of all its products. We are working with our customers to investigate reports of unfavorable symptoms observed on certain tree species, primarily Norway spruce and white pine," DuPont said in a statement. "We are evaluating our response to the complaint, but are confident that this purported class-action lawsuit is unfounded, and we will oppose it vigorously."

Narinda Kumar, who has lived in her Fishers home for seven years, first noticed her trees turning brown this spring.

"All the neighbors are just wondering why it is happening. We really don't know why," Kumar said.

The golf courses have stopped using Imprelis and are waiting for additional testing before they uproot the dead trees and start over.