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Do Emerald Ash Borer Treatments Work?

Updated: Apr 19, 2022

Written by: John Wayne Farber, Board Certified Master Arborist (BCMA) WI-0877B, Certified Treecare Safety Professional 01462

Insect pressure from Emerald Ash Borer EAB) is at a high point right now. The invasive insect is found in more than 70% of counties in Wisconsin, though it is most prevalent in the southeastern area of the state. It's a common sight to see ash trees going through the wood chipper as every day dying green ash and white ash trees are being removed by Hoppe Tree Service and others. Some homeowners feel resigned to the fact that they will have to remove their tree at some point once EAB comes to their yard, not realizing that there are treatment options. Others know there are treatments available, yet question their effectiveness. If you have a relatively healthy ash tree, you really do have options.

It is not a foregone conclusion that your ash tree will have to come down. Treatments do work, especially trunk injections with the active ingredient emamectin benzoate. Trunk injection treatments are proven; they have been used and tested for more than 10 years. Studies conducted by Michigan State University and Ohio State University using emamectin benzoate showed excellent control for EAB for at least two years, even when EAB densitites were at very high levels. In three research studies in Michigan, treated trees in close proximity to untreated trees had an EAB larval reduction greater than 99%. There was no sign of canopy decline in treated trees, while the adjacent, untreated trees showed severe decline. So, even if your neighbors decide not to treat their trees, your tree(s) can still be saved with treatment.

Is treatment worth it in the long run?

Trunk injection treatments are performed every two years, and cost-benefit analysis studies consistently show treatment costs are much lower than removal costs. Healthy landscape plants typically increase property values, provide shade and cooling, and contribute to the quality of life in the neighborhood. Read more about the economic, social and public health benefits of trees. Mature trees capture storm water and provide sentimental value as well. Researchers are actively studying whether treatment dosages can decrease and intervals increase between treatments after the initial wave of EAB has receeded.

How are treatments performed?

Emerald ash borer treatments are performed by a licensed pesticide application professional. Small injection sites are drilled into the base of the tree. The injection mixture is pumped into the tree using a pressurized system. The insecticide is absorbed and tranported within the vascular system of the tree, providing control against the EAB larval feeding stage.

Trunk injection has advantages over other EAB control options:

  • move quickly through the tree

  • can be performed on rainy or windy days, unlike foliar and trunk sprays

  • can be performed on trees with saturated soil, unlike soil insecticides

If you have an ash tree that you value and would like to keep, please consider treatment. Our certified arborists can help you keep your tree around for years to come.

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