How do I protect ash trees from emerald ash borer in Virginia?
Treat a healthy ash before the beetle weakens it. Virginia Department of Forestry says landscape and high-value ash should get a systemic insecticide, preventative treatment works best, and it may fail once more than 30 percent of the canopy is lost. Most treatments are repeated every one to two years and are done by a certified applicator.
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By Kasra Taheri, Founder, LoclisPublished
Researched and drafted with AI, then checked claim by claim against the sources listed below before it was published. Prices and rules change; the dates beside each source say when it was last checked.
Step by step
Read when to stop and call a pro, further down this page, before you start.
Step 1: Confirm the tree is an ash
Identify the species with your local Virginia Department of Forestry forester or an arborist, since the beetle attacks only ash.[1]
Step 2: Look at the crown
From the ground, estimate how much of the canopy has been lost, because treatment may not be successful when more than 30 percent is gone.[1]
Step 3: Check the bark from the ground
Look for woodpecker stripping of bark and small D-shaped exit holes in the trunk within reach.[1]
Step 4: Decide to treat or replace
Treat a healthy ash you want to keep; plan the removal and replacement of one that is already declining.
Step 5: Ask about cost-share
Contact your local DOF forester about the Emerald Ash Borer Treatment Cost-Share Program, which requires an assessment of the tree before enrollment.[3]
Step 6: Hire a licensed applicator
Choose a business with a pesticide business license and a certified commercial applicator to do the treatment.[4]
Step 7: Write the retreatment date down
Put the next treatment in your calendar, since most insecticides should be reapplied every one to two years.[1]
Treat a healthy ash tree early, before the borer has weakened it, and keep treating it on schedule. Emerald ash borer (EAB) is a beetle from Asia that feeds on the tissue under the bark of ash trees, and the Virginia Department of Forestry calls it the most destructive forest insect ever to invade the United States.[2] Ash is only worth protecting while most of the crown is still alive, and the treatment itself is a job for a certified applicator, not a trip to the garden center.
Know what you are protecting
The beetle attacks all native species of ash in North America.[1] It is hard to catch early, because symptoms may not be visible until a tree has already been infested for multiple years.[1] The most obvious sign is often bark stripping by woodpeckers hunting for larvae, and peeling bark reveals winding S-shaped galleries, while the adult beetles leave D-shaped exit holes in the bark.[1] Left alone, trees typically die within three to five years if untreated after infestation.[1]
Treat early, and know the cutoff
The forestry guide is direct: Landscape and high-value trees should be treated with a systemic insecticide.[1] Preventative treatment is most effective.[1] There is also a point of no return. When more than 30 percent of the canopy has been lost, treatment may not be successful.[1]
A treatment is not a one-time fix. Most insecticides should be reapplied every one to two years.[1] That ongoing cost is the real decision: a tree worth protecting is one you are willing to treat on a schedule for years.
Treat or replace
Treat an ash if it is healthy, in a spot you value, and has a crown that is largely intact. Replace it if the crown is already thin, or if the tree is a hazard near the house, a drive or a power line. Take the removal question seriously and read how to tell if a tree is dead or dangerous. To see what a visit would cost, see what an arborist costs in Virginia.
If you are not sure the tree is an ash, or the leaves are browning and you do not know why, start with why leaves turn brown in summer and how to treat a sick tree.
Help paying for treatment
Virginia has run a state cost-share for exactly this. The Emerald Ash Borer Treatment Cost-Share Program can help landowners and organizations offset up to 70% of costs for treatment of ash trees through stem injections with emamectin benzoate insecticide.[3] Payment may not exceed $10.50 per inch diameter at breast height or $2,000 in cost-share payments to landowners or $10,000 in cost-share payments per organization.[3]
Eligible trees are green, white, black, blue, pumpkin or Carolina ash that are 12 inches diameter at breast height (DBH) or greater, and all trees must be assessed by a DOF forester prior to enrollment.[3] The program is not always open: when we checked on October 27, 2026, the Department's page said the 2026 application period has closed.[3] Ask your local DOF forester about the next round, and check the page again before you plan around it.
Hiring someone to treat the tree
Virginia licenses the work. No person may apply or recommend for use any pesticide commercially without a pesticide business license and the employment of a certified commercial applicator.[4] When you get quotes, ask each company for its pesticide business licence, the name of the certified applicator, which product and method it will use, how often it will return, and what it will do if the tree declines anyway. Get the answers in a written quote, and compare quotes for the same trees on the same schedule.
Stop and call a pro if
- You see D-shaped exit holes, woodpecker stripping or peeling bark with S-shaped tunnels. Those are the beetle's signs, so get the tree assessed quickly, because treatment may not work once canopy loss passes 30 percent.[1]
- The crown is thinning or dying back. An ash that is losing canopy needs a professional assessment before you spend on treatment or decide to remove it.
- The tree is large, dead or leaning. Climbing, ladders and chainsaws are arborist work.
- A branch or the tree could reach the house, a car or a power line. Do not work near the line yourself; call a certified arborist.
- Someone offers to spray or inject without showing a licence. Ask for the pesticide business licence and the certified applicator's name first.[4]
Getting help in Virginia
Browse more lawn and landscaping answers, tree and shrub health services, or the lawn and landscaping directory. To decide whether a certified arborist is the right call, read when to call a certified arborist.
When you want a professional look, describe the problem once and local businesses quote it.
Common questions
- Do all ash trees in Virginia need treatment?
- Not necessarily. The Virginia Department of Forestry says landscape and high-value trees should be treated, which means an ash you value for shade, shape or location. An ash in a thicket you do not care about is a different decision. A forester or certified arborist can help you choose which trees are worth the repeated cost.
- How long does an untreated ash last once the beetle arrives?
- The forestry guide says trees typically die within three to five years if untreated after infestation. Symptoms may not show for several years, so by the time the crown thins, much of that time is already used.
- Is it too late if my ash is thinning?
- It depends on how much crown is left. The guide says that when more than 30 percent of the canopy has been lost, treatment may not be successful. Have a forester or arborist assess the tree before you pay for a treatment that may not work.
- Can I apply the insecticide myself?
- The state cost-share program pays for stem injections, which is a professional treatment. Anyone applying or recommending a pesticide commercially in Virginia needs a business licence and a certified commercial applicator, and the cost-share program covers stem injections with emamectin benzoate. Ask a certified arborist rather than relying on a product from a shelf.
- Does Virginia help pay to protect ash trees?
- Yes, through the Virginia Department of Forestry's Emerald Ash Borer Treatment Cost-Share Program, which has offset up to 70% of treatment costs for eligible trees. When we checked on October 27, 2026, the 2026 application period had closed, so contact your local forester to ask about the next one.
Sources
- [1] Tree and Forest Health Guide, Virginia Department of Forestry. Checked October 27, 2026.
- [2] Emerald Ash Borer, Virginia Department of Forestry. Checked October 27, 2026.
- [4] Va. Code § 3.2-3924. Annual business license required, Code of Virginia, Virginia General Assembly. Checked October 27, 2026.
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