NHBugs

Protecting trees and forests

Using Insecticides to Safeguard Individual Trees Against Emerald Ash Borer

Saving Your High-Value Ash

Management zones

Generally infested area
Emerald ash borer is in this zone, though not necessarily in all ash trees.

Potential expansion area
Emerald ash borer isn't known to be in the area, but the area is within 10 miles of the outer limits of the known infestation. There is a high probability emerald ash borer will spread naturally to this zone within a few years.

Alert area
Emerald ash borer isn't known to be in the area and it is more than 10 miles from the known infestation.

Definitions

Diameter at breast height (DBH)- Diameter of a tree at 4.5 feet above the ground

Systemic insecticideAbsorbed by the tree and moves inside. Applied on the ground or on the trunk.

 

 

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WARNING: Insecticides are chemicals that can have health or environmental impacts. If you use insecticides always follow all label instructions or hire a licensed pesticide applicator.
Pollinator impact note: Some studies have linked neonicotinoids, like imidacloprid and dinotefuran, to declines in pollinator populations. The body of evidence is inconclusive, but potential impacts to pollinators should be considered when initiating an insecticide regime. For information on insecticides used for EAB

Treating ash trees to protect against emerald ash borer (EAB) isn't automatic. Determine the following:

  • First decide if your ash trees are valuable enough to warrant protection.
  • Next, determine if your site lies in the generally infested area, potential expansion area, or the alert area (see map). Whether you treat and when you begin treatment depends on which area your valuable tree is in.
  • If you are in either the generally infested area or the potential expansion area and you’ve decided the values of your ash are high enough to warrant long term protection using insecticides, the next step is to decide the best product and delivery system for the tree size and location. 
Generally infested area and the ash tree is healthy

Use systemic applications of imidacloprid or dinotefuran products or switch to a product with emamectin benzoate (EB). Currently, Tree-äge is the only available EB product. Emamectin benzoate delivers better killing power over a longer period than other products (either imidacloprid or dinotefuran). Tree-äge is effective when applied every other year, but it can deliver high efficacy against EAB for up to 3 years. Tree-äge is labeled as a “restricted use” insecticide and can only be applied by a licensed professional. Tree-äge is only labeled to be applied through a tree-injection-system requiring plastic ports inserted into many small holes drilled in the base of the tree. The number of ports depends on tree diameter. The ports are left in the drill-sites after injection.

Generally infested area and the ash tree is unhealthy

Use an insecticide formulation of emamectin benzoate that is labeled for use against EAB. Products with currently available concentrations of imidacloprid don’t give high enough levels of protection to keep the tree healthy until the beetle populations decline.

Potential expansion area

Treat with a systemic insecticide product containing imidacloprid (examples: Xytect 2f, Merit 75wsp, or Bayer Advanced Tree and Shrub Insect Killer) or dinotefuran (examples: Transtect 70wsp, Safari 20sg) as the active ingredient. These products can be applied as a soil injection, soil drench or a basal bark application. These products do a good job of protecting the trees when the population of EAB is low and the tree size is under 18”dbh. These products don't provide adequate protection for larger diameter, older ash trees, or those that have experienced significant crown dieback, or where there is high EAB pest pressure. For those conditions, consider Tree-äge, a product containing emamectin benzoate, which can only be applied by licensed professional.

Alert area

It isn't advised to apply insecticides. Watch for signs and symptoms of infestation and monitor the available information regarding statewide outbreak locations. If the ten mile buffer or “expansion area” shifts to encompass your trees reconsider insecticide options.

Summary for using insecticides to protect high-value ash trees

When you find yourself within ten miles of an EAB outbreak and you have ash you want to save, start annual or semiannual treatments of systemic products with imidacloprid or dinotefuran. Best results are likely achieved by licensed applicators using superior products and having greater experience with potential application methods.

When the insect-killing-front is upon you and the beetle populations are high throughout your local area switch to a product with emamectin benzoate (EB) and perform direct tree-injections. After several cycles of tree injection with EB and if the beetle populations are declining in the area go back to the less invasive treatments of imidacloprid or dinotefuran products.

Insecticide rates and directions for application are found on the product label and must be strictly adhered toits the law. Seek advice of a New Hampshire licensed pesticide applicator for questions related to products, application costs and treatment efficacy.

For a more complete treatment of using insecticides to treat for EAB see:

 

Ash trees are:

Less than 18 inches dbh

More than 18 inches dbh

Generally infested area

 

 

Ash appear healthy

Imidacloprid, dinotefuran, or emamectin benzoate products

Emamectin benzoate products

Ash are in decline

Emamectin benzoate products

Emamectin benzoate products

Ash have greater than 50% crown dieback or are dead

Tree removal – translocation ability of tree is likely insufficient to deliver chemical for effective treatment

Tree removal – translocation ability of tree is likely insufficient to deliver chemical for effective treatment

Potential Expansion Area (within 10 miles of known EAB infestation)

Imidacloprid, dinotefuran, or emamectin benzoate products

Emamectin benzoate products

Alert Area (more than 10 miles from a known EAB infestation)

Treatment is not recommended. Stay informed about new EAB information.

Treatment is not recommended. Stay informed about new EAB information.

This information is given for educational purposes only and endorsement of insecticides use or the use of any specific insecticide product isn't implied. Every effort is made to keep information on this web page current. Seek advice of a New Hampshire licensed pesticide applicator for questions related to products, application costs and treatment efficacy.