In the absence of treatment, all native ash trees are vulnerable to rapid death from emerald ash borer.

Ash trees can be treated in a variety of ways to prevent their death. Both proven and unproven do-it-yourself products are available for treatment of emerald ash borer, or professional tree services can apply soil-injected or trunk-injected insecticides to protect the trees.

University-Proven Insecticide Treatment Options

University-proven treatment options work best when initiated on a preventive basisbefore emerald ash borer is found. They can also work when ash trees are showing low to (possibly as much as) moderate levels of emerald ash borer damage, when attentive, after-the-fact care is required. (For information on the four phases of infestation, see the Emerald Ash Borer Symptoms page.)

Soil-Applied Systemic Insecticides

  • University trials have proven soil-applied systemic insecticides containing imidacloprid to be effective, particularly on younger trees up to 15in. DBH (diameter at breast height).
  • Products available to homeowners are reliable if started early enough, dosed appropriately, and applied annually throughout the course of the pest’s population expansion and through the point at which its population finally crashes.
  • For trees exceeding 15in. DBH, a higher concentration of insecticide is necessary. These larger trees should be professionally treated because products available to homeowners do not carry the necessary concentration to be effective.

Leading emerald ash borer research has proven that insecticides are effective treatment options for EAB management. Insecticides are applied either through soil drench, soil injection or trunk injection. Each application method can provide at least season-long control of emerald ash borer.

Soil Drench/Injection

Soil Drench Application for Emerald Ash Borer Treatment

Soil drenching is a process of applying chemical to the base of a tree. The tree’s transpiration system absorbs the chemical and distributes it evenly throughout the three’s canopy without damaging the tree. This application method requires minimal equipment (a 5-gallon bucket will suffice), is quick and simple, cost efficient, and proven to provide season-long protection from emerald ash borer infestation when an approved insecticide is used.

Soil injection involves using a probe attached to either a backpack or truck-mounted spray rig to insert insecticide directly into the active root zone surrounding the tree. This method is more time-efficient for professional applicators treating multiple trees.

Trunk-Injected Systemic Insecticides

Trunk injection is a process by which chemicals are delivered directly into a tree’s vascular system through a series of tubing and tees. A single trunk injection of emamectin benzoate provides proven control for at least two years. To date, this is the only treatment that provides effective control for more than one year and is often used by municipalities. Because of the equipment requirements and insecticide needed for direct injection into the trunk, this method must be handled by tree professionals.

Basal Trunk Spray with Dinotefuran

Insecticide containing dinotefuran applied as a spray at the base of ash tree trunks has been shown to provide effective protection against emerald ash borer for one year. However, dinotefuran’s efficacy against emerald ash borer is highest when used on smaller trees. Further research results are pending to determine its long-term effectiveness.

Unproven Emerald Ash Borer Treatments

Other products and methods for the treatment of emerald ash borer infestations are available both professionally and directly to homeowners. However, any method not already discussed has not been found to provide effective control in university studies conducted to date.

Insecticide Options for Protecting Ash Trees from Emerald Ash Borer (PDF) – University of Minnesota Extension