Last year there was an outbreak of dying spruce trees in the upper mid-west. It appears that the culprit is a new herbicide that is being used mostly by commercial lawn care services called Imprelis. Imprelis is manufactured by Dupont Inc. (Here’s a link to Dupont’s Imprelis damage claims webpage) It does a fantastic job of killing dandelions and other broadleaf weeds as well as other hard to kill weeds such as creeping charlie. However, there was an unfortunate side effect in which trees were also absorbing the weed killer and for some varieties of trees it was doing severe damage to the tree. The trees that seem to be affected the most are Norway spruce and white pine trees. Other varieties of conifers are also effected as well. There are tell tale signs of injury that include twisting of new growth shoots and browning of needles especially towards the tops of the affected trees. The pictures above and below are taken from the University of Minnesota Extension’s web page.
If you have damage to a tree there isn’t much you can do. The only advice given at this point is to make sure the patient is as comfortable as possible and keep the tree from any additional stress. Because of the browning needles the first instinct of many home owner is to assume that the tree needs water. This can lead to over-watering and cause additional stress leading to additional damage to the tree. Water the tree when it’s dry but make sure not to over-water. Dupont also suggests avoiding fertilizing the tree for at least one year. Be sure not to compost or spread grass clippings treated with Imprelis anywhere that they could do harm to additional trees. Lastly, you should contact your lawn care company and ask them what they are using for fertilizer and report to them the suspected damage. Unfortunately, it appears that at this point it is a wait and see approach. Trees may be able to correct the damage themselves or they may suffer long-term effects from the damage or even die.
At this point it does not appear that there is any link to the harm of the trees and fertilizer (like Scotts) sold at retail stores. You may also want to consider using a more natural fertilizer that is less chemically based. You can also help your lawn naturally by not bagging your grass clippings. By leaving the clippings on the lawn the decaying clippings will naturally feed nutrients back into the lawn. Everything I’ve read so far states that Imprelis is only found in commercial herbicides. You can still use granular or liquid fertilizers and herbicides found at retail outlets such as our hardware store in Maple Grove.
Additional helpful links for more information about Imprelis:
Dupont’s page for care of stressed trees treated with Imprelis
Michigan State Extension’s page for A homeowner’s guide to Imprelis herbicide injury to landscape tree
University Of Minnesota Extensions page for Imprelis:
For more information we can be contacted at 763-553-1222
- Weed Control, Lawn Care, Fertilization Service (lawnpros7171.wordpress.com)
- Wisconsin: 29 lawsuits filed 2/23/12 alleged Imprelis-caused damage to trees (fdarecalls.wordpress.com)