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 the value of your ash trees, economic or cultural, are sufficiently high to warrant protection versus removal or replacement. Removals of mature urban landscape trees can cost several thousand dollars compared to several hundred dollars for pesticide treatments.
  • Next, determine if your site lies in the generally infested area, potential expansion area, or the alert area (see map). The time to begin treatments will depend on which area your valuable tree is in.
  • If you are in 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 chemicals like emamectin benzoate (EB), imidacloprid, dinotefuran, or azadirachtin. Current research indicates Emamectin benzoate delivers better killing power over a longer period than other active ingredients such as imidacloprid or dinotefuran but may be difficult to apply without significant investments in specialized equipment. Treating with an EB product requires the use of tree injection technology that create ports in the tree and delivers the product under pressure. Consult licensed professional pesticide applicators for more information.

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 neonicitinoids or azadirachtin don’t provide good efficacy in trees with poor crowns or high EAB populations.

Potential expansion area

Careful consideration should be given to treating trees in the expansion area.  Your trees are likely several years away from infestation.  Systemic pesticides labeled for EAB control only provide one to three years of control depending on the product.  Consider less invasive applications of pesticides where you don’t need to drill holes in the tree and inject the pesticide.  Bark applied pesticides or soil drenches could be used until EAB is known to be in the area. At that point you should switch to injected products with better efficacy.

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, consider starting semiannual treatments of systemic products containing imidacloprid, dinotefuran, or azadirachtin. Pay particular attention to limits on the amount of imidicloprid or dinotefuran that can be applied to your property annually. Best results are achieved by licensed applicators using the most appropriate products and having greater experience with various application methods.

When the EAB outbreak is causing damage in your town treat with products containing 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 to—it's 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, azadirachtin 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, azadirachtin or emamectin benzoate products

Emamectin benzoate products

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

Treatment is not recommended. Monitor EAB outbreak maps at NHbugs.org 

Treatment is not recommended. Monitor EAB outbreak maps at NHbugs.org

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.