Treatment for two-lined chestnut borers in old oak tree #833428

Asked June 02, 2023, 4:55 PM EDT

Hello, I live on a wooded lot in with many old (~100 yr) oak trees. Late last summer I saw some moderate crown die-off in one of the trees and this spring our local arborist confirmed damage from two-lined chestnut borers. While he said the tree would not definitely die, the prognosis was not great. He suggested that imidacloprid (Merit) could be used to as a potential last-resort treatment. My question is how I should best apply the insecticide, as I feel a bit overloaded with information. Some suggest applying directly to the tree about 4.5 ft. up while the Merit label suggests a soil drench or soil injection. I have never done a soil drench before but am willing to try if it could save the tree. Do you have any tips for this? Are there any unintended consequences from using it? I am aware of its impact to pollinators and aquatic life, though we are not near water and the oaks have already flowered, so I expect minimal impact on that front. I am also all ears if you think there is an alternate way forward. Thank you, Steve

Ramsey County Minnesota

Expert Response

Treating for Emerald Ash Borer can be confusing.  It requires an understanding of the importance of following the label of the product.  The label is the law with all agricultural/forestry chemicals.  You must follow the label instructions. The product must give the concentrations and the method of application for a soil drench.  
While I can’t say for sure without knowing the product involved, “the 4 ft up” method probably involves a tree injection.  Again the product label is by law requires to give the concentrations and methods of application.

The following website gives pertinent information and tips for homeowners who wish to treat their trees.
Hope this is helpful.
Mary, Master Gardener, Tree Care Advisor Replied June 02, 2023, 9:46 PM EDT

Loading ...