A DuPont herbicide, Imprelis, marketed to professional landscapers this spring as an environmentally friendly product, is suspected of severely damaging or killing thousands of Norway Spruce and White Pine trees, some of which grow to be 80 or 100 feet.
Imprelis was intended for use as a post-emergent broadleaf weed killer to eradicate the likes of dandelion, clover, plantain, ground ivy, wild violets, and henbit. It was applied to golf courses, cemeteries, public parks, athletic fields, and lawns by landscaping companies nationwide.
Since mid-June, professional landscapers have reported thousands of complaints from customers whose Norway Spruce and White Pine trees are exhibiting wilted, necrotic, yellow needles; dead needles; wilted new shoots; desiccated and drooping candles; and twisted and distorted shoots. In most cases it appears that these stately evergreens reacted to Imprelis four to six weeks after the grounds near them were treated. In Columbus, Ohio alone, over two thousand evergreens have been damaged.
The Environmental Protection Agency announced Friday that they will begin an expedited review of Imprelis by the end of this month. Their ruling will determine if Imprelis is removed from the market or has its labeling revised.
Pete Landschoot, professor of turf-grass science at Pennsylvania State University, wrote in June, “In some cases, injury does not progress much further than slight curling and browning of new growth; however, in other cases complete dieback is observed. In severe cases, the entire tree turns brown and begins to lose its needles. It’s as if the trees were being poisoned through the roots, from herbicide spread deep by the soaking spring rains.”
DuPont’s package label warns that grass clippings treated with Imprelis should not be used as mulch or put in compost piles, as Imprelis will survive the composting process and will still be active in the finished compost. Unsuspecting gardeners may damage their favorite flowers or vegetables, many of which are broad-leafed, just like the intended target plants.
So what are you to do if you suspect that one of your trees is suffering from Imprelis damage? DuPont has suggested that you surround the base of the tree with a soaker hose in an attempt to wash the chemicals through the soil. However, other scientists disagree with this suggestion, as Imprelis needs the activity of soil organisms to break it down, and waterlogging your soil will slow that action. In addition, DuPont warns that Imprelis has a high potential of polluting surface water via runoff for several months after application, so applying water to the poison and encouraging its movement may not be the responsible thing.
It’s ironic that Imprelis was marketed in a March press release as adding “to DuPont’s expanding portfolio of green industry products…with a reduced environmental impact.”