Emerald Ash Borer in Central Ohio: Signs, Treatments, and How to Save Your Tree

If you have an ash tree in Central Ohio whether you’re in Columbus, New Albany, or the surrounding suburbs the emerald ash borer (EAB) is probably the single biggest threat it faces. This invasive beetle has killed the vast majority of untreated ash trees across Ohio over the past two decades, and it doesn’t slow down once it finds a host tree. The good news is that EAB is highly treatable if you catch it early, and knowing what to look for is the first step.

What is the Emerald Ash Borer?

The emerald ash borer is a small, metallic green beetle whose larvae tunnel under the bark of ash trees, cutting off the tree’s ability to move water and nutrients. By the time damage is visible from the ground, the infestation is often already well established. Nearly every ash tree in Ohio that isn’t treated will eventually be affected.

Signs Your Ash Tree May Have EAB

• Canopy thinning or dieback: Usually starting at the top of the tree and working its way down.

• D-shaped exit holes: Small holes in the bark about the size of a grain of rice.

• Splitting bark: Revealing S-shaped tunnels (galleries) underneath the surface.

• Increased woodpecker activity: Woodpeckers heavily forage on the bark to feed on the larvae underneath.

• Epicormic sprouting: New, leafy shoots rapidly growing from the lower trunk or base as the tree tries to compensate for canopy loss.

Any one of these signs on its own isn’t a guaranteed diagnosis. However, a combination of two or more-especially a thinning canopy paired with exit holes-is a strong signal that it’s time for a professional tree assessment.

Why Early Identification Matters

Ash trees can decline surprisingly fast once EAB takes hold, sometimes within two to three years from the first symptoms to complete tree death. A tree caught early, while the canopy is still mostly intact, has a much better chance of responding well to treatment. A tree that has already lost more than half of its canopy is a much harder case, and in some situations, professional tree removal becomes the safer and more practical option.

What to Do If You Suspect EAB

The tunneling and canopy loss caused by EAB also severely weaken a tree’s structural integrity. This becomes a real safety concern for any tree growing near a house, driveway, or anywhere people walk and park. If you’re seeing any of the signs above, the right move is to have an ISA Certified Arborist take a look before deciding between saving the tree or safely removing it.

Can My Ash Tree Be Saved?

The short answer is yes-most trees are savable if they have more than 50% of their crown intact.

Here in Central Ohio, EAB populations tend to ebb and flow as new forested ash saplings grow, become infected, and then die. Because we are no longer in the initial, devastating wave of the borer, the pest pressure is typically not high enough to instantly decimate an isolated ash tree. Emamectin benzoate is the best EAB treatment option available and has a 20-year track record of successfully controlling the borer.

What to Expect After Tree Treatment

There are a few very important things to keep in mind once you begin an EAB treatment program. First, the treatment is designed to kill the borer upon ingestion; it does not put a barrier over your tree that repels the insect from landing. Because of this, borers can still cause minor damage before the treatment stops them, meaning you might occasionally see new, small dead branches pop up even on a tree that has been treated for years.

You may also continue to see larger dead branches form after treatment has started. There are two reasons for this:

1. Lagging Damage: The borer’s internal damage hasn’t completely revealed itself yet. It typically takes two to three years after treatment begins to stop losing larger limbs, though this is solely dependent on the condition of the tree prior to treatment.

2. Unrelated Stress: Ash trees can decline for other reasons. While the biggest issue with ash trees is the borer, your tree can still experience drought stress, root problems, and the typical aging associated with any mature tree.

At Arborist Solutions, we offer expert emerald ash borer treatment and diagnosis throughout the Columbus area. Every recommendation starts with an honest assessment of whether a tree is a good candidate for treatment or if removal is the safer route. If you’re noticing thinning, exit holes, or unusual woodpecker activity on an ash tree, reach out for a consultation, and we’ll help you figure out the right next step.