News and Information
Imprelis Herbicide Injury to Evergreens
By: Dr. Kevin Frank
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: www.ppdl.purdue.edu/PPDL/hot11/6-10.html. 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.