The active ingredient in Imprelis, aminocyclopyrachlor, is highly effective on many difficult to control turf weeds such as ground ivy since, unlike most common turf weed killers, the compound is actively taken up by roots. While this property helped Imprelis take out tough weeds, it also resulted in severe damage and death to trees, especially Norway spruce and eastern white pine trees.
The U.S. Environmental Protection Agency issued a stop-sale order for Imprelis in July 2011. After the product was pulled from the market, DuPont established a claims process for affected property owners and received over 30,000 damage claims. Total damage estimates range in the hundreds of millions of dollars
Bert Clegg of Michigan State University Extension, Department of Horticulture and Forestry, in early June posted a concise look at some recent findings about Imprelis regarding tree recovery (or non-recovery), soil and plant residual and the settlement process. He also posted (in the MSU Extension News) some tree images that should be interesting to anybody following the Imprelis situation.
To read the MSU piece and view the images please click here.