A rash of tree deaths may be caused by a weed killer, Imprelis. Thousands of Norway spruce and eastern white pine may have been killed by Imprelis, a herbicide intended for lawn use that leaches into the soil and affects adjoining trees. The tree deaths have spawned numerous lawsuits, reports the New York Times.

Experts at Purdue University and the University of Michigan say the herbicide damaged trees show symptoms of injury that includes curling and twisting of new growth. Pictures and comments of damage observed in Indiana can be viewed at Purdue Extension’s Plant and Pest Diagnostic Laboratory website.

The Office of Indiana State Chemist lawn care operators  and homeowners have reported twisting and curling of new growth in Norway spruce and white pine. "DuPont, the manufacturer of Imprelis, is also aware of the issue and reportedly will release a statement on the situation in the near future," says the Indiana State Chemist's office. 

DuPont  Impreli herbicide was registered by the U.S. Environmental Protection Agency last fall. It controls dandelion, clover and plantains and broadleaf weeds  like ground ivy and wild violets."Its single active ingredient has one of the lowest application rates, combined with low toxicity to mammals and low environmental impact," said DuPont as Imprelis was released to the market. 

DuPont says it carried out over 400 field trial protocols to evaluate Imprelis before releasing it. Studies show that it is effective against many hard-to-control weeds, is not impacted by rain, hot temperatures or cool temperatures, and provides unprecedented levels of broadleaf weed control when applied on granular fertilizer. Imprelis™ will be available in 2.5-gallon, 1- gallon and 4.5 ounce bottles.

The single active ingredient in Imprelis™ is the first compound in an advanced generation of herbicides. Discovered by DuPont, this new chemistry subclass has unique properties at both the
molecular and whole plant levels that translate into more powerful herbicidal activity. Imprelis™ is readily absorbed by plant leaves and roots, stopping the growth of target weeds by interfering with the hormonal balance necessary for normal shoot and root development. Herbicide symptoms typically first occur within a few hours to a few days after application. The most noticeable symptoms include the bending and twisting of stems and the cupping of leaves.

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