A new weedkiller that was recently approved by the EPA is now suspected of killing more than weeds. Large shade trees, including willows, poplars, Norway spruce, and white pines, as well as smaller shrubs and ornamental plants, are turning brown and dying after the herbicide was sprayed near them. Homeowners, golf course managers, and plant-nursery employees are in an uproar, as thousands of plants wither. Here, a brief guide:

What is this new herbicide?

It's called Imprelis, and is marketed to landscape professionals. You probably won't find it on the shelves of your local hardware store. Imprelis is one of a group of herbicides that, ironically, was developed to be safer and more environmentally friendly than older herbicides. The Environmental Protection Agency (EPA) gave the weedkiller conditional approval last year, while it continued to review its safety data. Some states, like California and New York, have not yet approved Imprelis for use.

Does it kill everything around it?

No, according to records from the EPA and DuPont, the manufacturer of Imprelis. They tested the herbicide hundreds of times on a range of plants, and found that it is safe and effective, especially on troublesome weeds like dandelions, clover, and ground ivy. Preliminary tests also showed that it caused no damage to other plants, but testimonies from homeowners and groundskeepers nationwide cast doubt on those studies.

What are users of the herbicide finding?

A Delaware couple claims that Imprelis is responsible for poisoning 10 large white pines on their property. "They look deformed," says homeowner Dwight Shamp, as quoted by DelawareOnline. "Some of them are completely brown and needles have fallen off. They look like last year's Christmas tree." Other users of the weedkiller, including condominium associations and the operators of cemeteries and athletic fields, have voiced similar complaints.

What's being done about these tree deaths?

While the EPA has fast-tracked a review of the weedkiller, a Pennsylvania homeowner and a Michigan golf course operator, who claim that Imprelis is responsible for $5 million in damage to their two properties alone, have initiated a class-action lawsuit against DuPont. The company is investigating claims of tree deaths nationwide, but it continues to insist that the herbicide is safe when used as directed. DuPont says 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."

Sources: DelawareOnline, Detroit Free Press, New York Times, (2), Technorati