Imprelis herbicide may injure evergreens

There have been reports of damage to evergreens following the application of the turfgrass herbicide Imprelis (a.i. aminocyclopyrachlor).

There have been several reports from both outside and within the state of Michigan of herbicide injury on Norway spruce and white pine following application of the turfgrass herbicide Imprelis (a.i. aminocyclopyrachlor). Damaged trees have symptoms consistent with growth regulator type herbicides. Injury 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.

DuPont is in the process of investigating the issue and their initial conclusions indicate that in most cases, Imprelis was applied in combination with other pre- or post-emergence herbicides or liquid fertilizer. Most Imprelis applications have not resulted in damage to spruce or pine, but obviously cases of damage cause alarm when dealing with a newly released herbicide. DuPont advises to not apply Imprelis “where Norway spruce or white pine are present, or in close proximity to, the property to be treated.”

Furthermore, DuPont advises, “When applying Imprelis, be careful that no spray treatment, drift or runoff occurs that could make contact with trees, shrubs and other desirable plants, and stay well away from exposed roots and the rootzone of trees and shrubs.” The reported cases from Indiana indicate that this may not be a simple herbicide drift issue, but rather from root uptake. If that is the case, it would be critical to keep applications away from the rootzones of non-target trees and ornaments. As with any pesticide application, always make sure to read and follow label directions.

Related article:
What to do with Imprelis-affected trees.

Related resource:
pdf fileA homeowner’s guide to Imprelis herbicide injury to landscape trees

 

Dr. Frank’s work is funded in part by MSU’s AgBioResearch.