If you live in the Midwest or Eastern United States you’ve likely been hearing a lot about the emerald ash borer (EAB) over the last 10 years. Researching EAB can be overwhelming. But, fear not! We’re here to help. In this article we’ll help you identify the signs of EAB, discuss how to evaluate whether to treat your ash tree, and options for emerald ash borer treatment.
EAB is a wood-boring beetle native to Asia and was initially found in the Detroit, MI area in 2002. Since then it has spread to over 35 states in the central and eastern parts of the US and into several Canadian provinces.
This little green beetle has wreaked havoc on ash tree populations and devastated the tree canopies in these areas, resulting in the removal of hundreds of millions of trees.
Adult beetles are metallic green and about 1/2 inch long. They only feed on ash trees. Females lay eggs in bark crevices on ash trees and larvae feed underneath the bark to emerge as adults in one to two years. By eating this tissue underneath the bark they slowly kill the trees.
Symptoms & Signs of EAB
Is my ash tree affected by EAB?
EAB attacks all native species of ash including white, green, black and blue ash. If you are in the greater Madison or Milwaukee, WI areas, your ash tree is likely a host to EAB. As of 2021, EAB has been found in most of the southern counties in Wisconsin. If you’re a resident of WI you can refer to this map to find out if EAB has been identified in your area.
EAB has also been found in most states east of the Mississippi River. This site features two maps, one showing which states have EAB and another one identifying EAB discoveries on a county level.
If you’re unsure whether your ash tree is being affected by EAB call a certified arborist (like us!) to come and evaluate your tree.
If your ash tree has EAB and you’d like to keep it alive, immediate treatment is imperative. We’ll talk more about that later.
What are the signs of EAB?
If you live in an area where EAB is prevalent (for example, most of southern WI) your tree is likely infected, even without these signs that indicate an advanced infection. It can take 2-4 years of damage for the following signs and symptoms to appear.
- Woodpecker damage: Woodpeckers like to eat EAB larvae. If your Ash tree has extensive damage it may be a sign of EAB infestation.
- Canopy dieback and thinning: As the larvae feed on the tree they disrupt the flow of nutrients and water into the upper canopy of the tree. This results in dying leaves during the first three years of infestation and eventually leads to branch and tree death.
- Bark splitting: Splitting bark is the result of calluses that form around the areas where larvae are feeding. If you look beneath the split you’ll find either the small white larvae or their s-shaped tunnels.
- “D” shaped exit holes on trunk: As adults emerge from the bark they create an exit hole that is approximately 1/8 inch in diameter
- “S” shaped tunnels under bark: As larvae feed under the bark they wind back and forth, creating serpentine galleries packed with frass, or the digested woody materials created by wood-boring insects.
- Presence of the emerald beetle: Adult beetles are metallic green and about 3/8- to 1/2-inch long and 1/16-inch wide. The best time to see an adult EAB is a warm, sunny afternoon when they are likely to be either mating or laying eggs on the trunks of ash trees. If you see one, send us a photo! It’s rare for the guest of (no) honor to make an appearance.
Emerald Ash Borer Treatment Options
The only way to protect your ash tree from EAB in infected areas is to apply an insecticide treatment. Insecticides can prevent healthy trees from being infected and can treat trees with low to moderate infestation rates.
How do I know whether to treat my tree?
Whether or not to treat your ash tree for EAB is a personal and subjective decision. Some factors we consider when recommending treatment vs. removal are:
- Is the tree healthy?
- Is the tree an integral part of your landscape? Does it offer shade in the summer months (reducing cooling costs) or other benefits?
- How much will it cost to treat vs. remove the tree?
If EAB has been found in your area, you may want to treat your trees to avoid future infestation or prevent further damage if the trees are already lightly infested.
If you’re unsure whether or not you should treat your tree, make an appointment with a certified arborist that offers both tree removal and insecticidal treatments for EAB.
What will happen if I don’t treat my tree?
If your tree is infected with EAB and you choose not to treat it death is inevitable. The time frame depends on the tree’s overall health and its environment. You will eventually have to remove the tree.
How much will it cost to treat my tree?
Arborists calculate the cost of treating your ash tree based on tree size and location, the type of insecticide used and the application method. To get the most accurate quote you’ll need to make an appointment for an arborist to visit your property and see the tree in person.
When talking with the arborist make sure you understand which insecticide will be used, how it will be applied, and how often reapplication will need to occur.
What should be used to treat my tree?
When receiving treatment for EAB, it is important to know which insecticide they’ll be using to battle the borer. The most effective chemical on the market for emerald ash borer treatment is emamectin benzoate.
Emamectin benzoate is a trunk-injected insecticide used by professional insecticide applicators (e.g., certified arborists). Products containing this ingredient only need to be used every two years compared with other insecticides which need to be apply every year.
How do I go about treating my ash tree?
We recommend hiring a certified arborist to treat your ash tree. As professionals we have access to specialized application equipment and additional insecticides not available to homeowners. We’re also trained to measure trees accurately and assess the overall health of trees.
Can I treat my tree without a Certified Arborist’s help?
In order to purchase and inject emamectin benzoate in many areas (including Dane County, WI where we’re located) you must have a Pesticide Applicator’s License. The injection equipment is also quite expensive.
Local gardening centers may sell insecticide products that a homeowner can apply. While the price tag might be appealing, the reality is that these insecticides are not as effective emamectin benzoate and it’s likely your tree will still succumb to the borer. It just might take a year or two longer.
How often is the treatment repeated?
Emamectin benzoate must be injected every two years to remain effective. Other insecticides are injected every year.
If you choose us to treat your ash, there’s no calendar required! At ECO Tree, we will keep track of your tree’s history and let you know when your tree is due for treatment.
Any alternatives to treatment?
Given the serious threat of EAB, removal and replacement of the tree is the only viable option other than treatment. Keep in mind, the tree will become hazardous as it declines and if left too long the cost of removal will increase as the tree becomes more hazardous.
Can I plant an ash tree?
Technically, yes. But without knowing how EAB will evolve, we strongly recommend that you choose a different tree.
If you have an ash tree on your property, call us today at (608) 886-0626 to discuss your options for emerald ash borer treatment. We’ll come check it out, free of charge, and share our expertise with you!