Emerald Ash Borer Treatment

Emerald ash borer (EAB) was first spotted in NJ in Somerset county in 2014, although its destructiveness has killed millions of ash trees since 2002 in the US and Canada. 

As of July 2017, emerald ash borer has been positively identified in New Jersey in Bergen, Burlington, Essex, Hudson, Hunterdon, Mercer, Middlesex, Monmouth, Somerset and Warren counties, although it’s probably present across the entire state, as well as in nearby Bucks County.

The problem is serious enough that the entire state of New Jersey is under quarantine for the movement of ash wood and firewood to slow the spread of EAB.

The state also recommends that you take one of two actions ASAP –

1. Treat any ash trees on your property that you want to save
2. Remove all other ash trees

Waiting is no longer an option. Untreated trees will be dead within 2 to 4 years. Dead EAB-infested ash trees pose a serious hazard in the landscape as they’re unstable, prone to failure and more difficult to remove safely.

Please contact us if you’d like an estimate for removing ash trees on your property.

For treatment options, keep reading.

How Emerald Ash Borer Treatment Works

Treatments for emerald ash borer primarily rely on the tree taking up insecticides or treatments through the xylem to the other parts of the tree. The xylem acts much like the arteries of the human body, and distributes water to the rest of the tree.

Unfortunately, this is also the part that of the tree that the EAB eats. As it eats the xylem, it starts to cut off the flow of water and nutrients, which then kills the tree.

When To Apply EAB Treatment

Since treatment of EAB also relies on the xylem for transportation, the best practice is to inoculate and pre-treat trees that show mild signs of infestation before so much damage is done that the tree no longer can move water (or treatment) effectively.

Adult emerald ash borers emerge between May and June. After 14+ days eating the ash leaves, they begin laying eggs. This time period (May through June) is the best time to spot and identify EAB in ash trees.

Treatment requires 30-60 days to take effect and is directed primarily at newly emerging larvae. EAB eggs tend to hatch between June and August, and younger larvae are most susceptible to treatment. As the larvae mature, treatment becomes less effective.

The optimal time for emerald ash borer treatment is mid-May to mid-June, although it can be done through mid-fall.  Treatment is less effective later in the season and more must be used to get the desired effect, but it’s better to treat your ash tree when you notice an EAB infestation rather than waiting.

Emerald Ash Borer Treatment Options

When deciding on the best treatment method for your ash trees, there are two things to consider: the chemicals (insecticides) used and the application method.

Insecticide Options

There are three types of insecticides that have shown effectiveness against emerald ash borer. Two are synthetic chemicals and one is organic.

TreeAzin

TreeAzin is a Canadian-sourced, organic insecticide based on neem extracts (however, it is NOT neem oil). It works differently from neonicitinoids by interrupting larval growth and egg viability in adults, leading to population decline and insect death.  Studies seem to show no adverse effect on litter decomposers (worms) or aquatic insects (even in higher concentrations) though this may be due to overall lower concentrations of TreeAzin in leaves.

Given the relative safety of TreeAzin and its strong effectiveness, this is the insecticide we use to treat emerald ash borer.

For homeowners concerned about impacts on the environment and those who prefer to use organic products, this is the EAB treatment of choice.

Imidacloprid & Dinotefuran

These synthetic insecticides belong to the class of chemicals known as neonicotinoids. Concern has been raised about their usage (particularly imidacloprid) due to its relation to colony collapse disorder in honey bees. However, ash trees are not a food source for bees (ash trees are wind pollinated, and ash blossoms are present for a very short period of time), thus reducing concern about using neonicotinoids to treat EAB in ash trees. It is effective against EAB at all stages and kills them through ingestion or upon contact.

Research suggestions that it may be toxic to birds and aquatic life, especially aquatic invertebrates (animals that are food for fish, but not the fish themselves), so avoid spraying where it can drift into ponds, rivers or lakes.

Emamectin

This broad spectrum insecticide is often used to treat EAB but is most likely to affect other species of plant feeding insects.

A recent report from the Environmental Protection Agency concluded that:

“Emamectin benzoate has the potential to reduce survival, reproduction, and growth in non-target terrestrial and aquatic animals including invertebrates when used in accordance with the current label. These organisms include Federally listed threatened and endangered non-listed species.”

A common EAB treatment that uses emamectin benzoate is TREE-äge®.

Application Methods

Trunk Injection

Injecting insecticide directly into the xylem requires professional application. This method is faster-acting than other options and much more targeted. Not hiring a professional may result in improper dosages and permanent damage to the tree (multiple holes must be carefully drilled into the tree in order to inject the insecticide). Extremely dry conditions can slow down distribution of the treatment throughout the tree.

This is the method we use here at Organic Plant Care LLC as it has the least chance of impacting the surrounding area or affecting non-target animals/insects.

Foliar Spray

Spraying leaves on ash trees is done only to treat adult beetles and any larvae that might emerge from the bark (in other words, foliar sprays are applied after the damage is done). Frequent treatments are needed (every 4 months) and insecticide drift is a major concern (spraying often hits other plants as well).

Trunk Spray

This method is noninvasive to the tree. It shows as much effectiveness as soil drench and, when applied correctly, can work as quickly as trunk injections. Trunk sprays are only done with dinotefuran, which is more water soluble than imidacloprid. Treatment remains effective for about one year.

Soil Drench

Soaking the soil with insecticide can be effective. However, it often produces inconsistent results, takes longer to be transported throughout the tree and raises concerns about chemicals seeping into groundwater and contaminating water sources, as well as effects on insects and worms in the soil. Although the insecticides used in soil drenches tend to break down when exposed to light, they can remain in soil and water for a long time. Treatment should be repeated yearly and requires a higher concentration of insecticide than other methods.