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

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.

Why Fertilization Alone Is Not Enough for Trees

Fertilizing your trees can be a very important step to keeping them healthy in an urban environment. But one step that is commonly skipped is actually enhancing the soil while performing this fertilization. The difference between feeding trees and building soil fertility is more significant than most homeowners realize.

We can go down a deep rabbit hole when talking soil science, but today we are just going to scrape the surface.

The Problem With Standard Tree Fertilization

Fertilization is commonly done as a liquid fertilizer or a granular/solid fertilizer. While each has its pros and cons, our preferred method is liquid fertilizer delivered via vertical mulching — more on that in a moment. For trees, liquid fertilizer should be delivered with a wand that goes between 6 and 12 inches deep.

Many of the fertilizers used for trees and lawns add little to no organic matter to the soil. They add an abundance of NPK (nitrogen, phosphorous, and potassium) which is good for plants in the short term, but does not replenish the soil of anything taken up by the plants. Chemical NPK is quickly available for the plants — but then is flushed from the soil after only a few weeks or months.

Soil Enhancement: What Actually Works

We prefer soil conditioners with a lower percentage of NPK paired with other organic materials. When it comes to liquid fertilizer, we prefer seaweed extract, mycorrhizal fungi, humectants, and naturally sourced surfactants to help mitigate hydrophobic soil rapidly.

We also use what we call “hard fertilization” — using an air spade that blasts compressed air at high speed to expose roots and mitigate soil compaction without damaging the root system. After we blast holes or trenches, we fill them in with a mix of leaf compost, comtil, fine-meshed pine bark mulch, worm castings, and other amendments on a case-by-case basis. This method costs more upfront, but yields long-term benefits to both the soil and the trees simultaneously.

What You Can Do Yourself

There are things you can do to improve your soil without hiring an arborist. Do not rake your leaves — mulch them instead. It only takes the lawn mower a few passes to mulch them up well, and the impact on soil health over time is significant. You can also spread worm castings over your yard or root zone using a spreader. Worm castings have a high concentration of nutrients and will help replenish the soil at a fairly rapid pace.

Think Soil First, Trees Second

When considering fertilization, it is always best to think about it as building fertility in the soil rather than feeding the trees. This will greatly improve the health of all of your plants and help the soil build a diverse, healthy microorganism population that supports tree health for the long term.

If you have trees that are showing signs of decline, poor vigor, or slow growth, a soil assessment is one of the first things we evaluate during a consulting visit. Our plant health care program includes soil amendment as a core component of everything we do.

James Benedetto — Owner, ISA Certified Arborist OH-7011A, Arborist Solutions