Spring treatments for emerald ash borer

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Updated from an original article written by Dave Smitley, Michigan State University Extension, Department of Entomology.

If you live in a county where emerald ash borer has been found, and you have decided to try to save your ash tree with annual insecticide treatments instead of replacing it, keep the following tips in mind

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

If you live in a county where emerald ash borer has been found (see emeraldashborer.info to find out), and you have decided to try to save your ash tree with
annual insecticide treatments instead of replacing it, keep the
following tips in mind:

  • Be sure you identified your ash tree correctly (see emeraldashborer.info).
  • Decide whether you prefer replacing your tree or insecticide treatments.
  • Insecticide treatments are most effective when started when trees are still healthy.
  • Homeowners can drench around the base of ash trees with Bayer Tree and Shrub Insect Control (imidacloprid) in May or early June, each year.
  • Imidacloprid drenches do not provide much protection to large trees in the first year of drenching, but work well each year after that.
  • If you see some dieback or canopy thinning now or next year, you should also use ACECAP implants or Bonide Systemic Implants in early May or hire an arborist to do a trunk injection in addition to the drench.
  • If your ash tree already has 50% (see Images) or more canopy dieback or canopy thinning, your chances of success with insecticide treatments are not as good.

      For more details, see MSU Extension Bulletin E-2955: Homeowner Guide to Emerald Ash Borer Treatments.You can find it at emeraldashborer.info

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

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