Emerald Ash Borer Has Already Won in Portage and Summit County. Here's What to Do Now.

What the borer actually does, and why you can't see it until it's bad

Emerald ash borer is a half-inch metallic green beetle from northeast Asia. The adult chews a tiny D-shaped hole in the bark, lays eggs in the bark crevices, and the larvae hatch and bore into the layer of living tissue just under the bark. That layer — the phloem — is how the tree moves sugars from the leaves down to the roots. The larvae spend the next year or two eating S-shaped tunnels through that tissue, then chew their way back out as adults the following spring.

One larva isn't a big deal. A few hundred larvae will girdle a branch. A few thousand will kill a whole tree. Mature ash trees in our area routinely host tens of thousands of larvae by the time anyone notices.

The problem is that you can't see any of this from the outside until the damage is severe. The exit holes are small and high in the crown. The tunnels are under intact bark. By the time you see thinning in the canopy, the tree has already lost most of its ability to move resources, and the next thing that happens is the upper crown dies.

What you're actually looking at when you walk up to an infested ash

There are specific visual signs and they show up in roughly this order:

1. 1

   Thinning in the upper crown first. Ash trees die from the top down, which is unusual — most stressed trees die from the outside in. If the very top of your ash looks sparse compared to the lower limbs, that's the borer signature. Drought damage doesn't do that.

2. 2

   Epicormic sprouts — those weird clusters of leafy shoots coming directly out of the trunk and main limbs, often at strange angles. The tree is trying to grow new leaves anywhere it still has functioning tissue. Looks almost like a beard of leaves on the trunk. This is a distress signal.

3. 3

   Vertical bark splits, usually six inches to a couple of feet long, that expose lighter wood underneath. If you peel back a flake of bark near one of these splits, you'll see the S-shaped galleries packed with brown frass. That's diagnostic. Nothing else does that pattern.

4. 4

   Woodpecker damage, which on an ash tree is called blonding. The bark gets stripped off in patches by woodpeckers going after the larvae underneath, and the exposed sapwood is a pale tan color that stands out from a hundred yards. If your ash tree looks like someone took a wire brush to random sections of the trunk, that's heavy borer pressure and heavy woodpecker feeding.

5. 5

   D-shaped exit holes, about an eighth of an inch across, with one flat side. You usually have to be up in the tree to see them clearly. By the time these are obvious from the ground, the tree is well past saving.

The line between treatable and not

Here's the honest assessment, and it's the same one I give in driveways every week.

If your ash tree still has more than about 70 percent of its canopy intact, no significant dieback in the upper crown, no bark splitting, and no major woodpecker blonding — and if you're willing to commit to treatment every two to three years for the rest of the tree's life — it can probably be saved. The treatment is emamectin benzoate, injected directly into the trunk by a licensed applicator. It's expensive. For a large ash, you're looking at a few hundred dollars every other year, indefinitely. It works. There are treated ash trees in our area that have been healthy for fifteen years now while every untreated ash around them is gone.

If the canopy is more than about 30 percent thinned, or if you can see significant dieback up top, or if the bark is splitting — the tree is not coming back. Treatment at that point doesn't reverse the damage. The phloem that's already been destroyed doesn't grow back. You'd be paying to slow a death that's already happened.

There's a middle zone where it's a judgment call. I look at the specific tree, where it is, what it's worth to the property, and whether the homeowner is willing to commit to long-term treatment. Some of those trees we treat and they pull through. Some we treat and they decline anyway. That's just how it goes.

“A dead ash tree is not the same risk as a dead maple or a dead oak. Ash dries out faster, gets brittle faster, and starts shedding limbs much sooner. Two years after death you're looking at a tree that drops branches in calm weather.”

Why standing dead ash is a different kind of problem

Most hardwoods, when they die, stay structurally intact for a long time. An oak that died last year is still going to be there in five years, dropping a branch here and there but mostly standing. Ash is different.

Once an ash tree dies, the wood dries out quickly and becomes brittle. The bark falls off in sheets within a year or two. The smaller branches start dropping on their own. Within three to five years, large limbs are coming down without warning, and the trunk itself becomes unsafe to climb. We have to take dead ash trees down with cranes or bucket trucks because nobody should be tying into one with climbing ropes. They snap.

This matters for two reasons. First, the cost of removal goes up the longer you wait, because the tree gets harder and more dangerous to handle. A dead ash we take down this year might be a $900 job. The same tree in three years is a crane job at $2,500 because we can't put a climber in it. Second, the risk to your house, your car, and your neighbors goes up every month. Dead ash trees are the single most common cause of unexpected limb drops I see in Northeast Ohio. They fall in light wind. They fall in no wind.

If your neighbor has a dead ash and you don't

This comes up a lot, especially in older Kent and Akron neighborhoods where lots are close together. Your neighbor has a 60-foot dead ash leaning vaguely toward your property line. They haven't done anything about it. What now.

In Ohio, if you can document that you notified them in writing about a hazardous tree on their property, and the tree later falls and damages your property, their insurance is much more likely to pay. Without that notification, the legal default is that a falling tree is an act of nature and your insurance handles it, not theirs. So if you have a clearly dead tree threatening your property, send a polite certified letter. Keep a copy. That single step changes the insurance math significantly if something goes wrong.

If they still don't act and you're genuinely worried, you can sometimes negotiate to pay for or split the cost of removal. I've worked a lot of jobs where two neighbors went in together because one of them couldn't afford it on their own and the other one couldn't sleep knowing the tree was there.

What to do this season

Walk your property. Identify every ash tree you have — they have compound leaves with five to nine leaflets, diamond-pattern bark on mature trees, and opposite branching (twigs come off the limbs in pairs directly across from each other, which is uncommon).

For each one, take an honest look at the upper crown. If it's full and healthy, you have a candidate for treatment and you should make that decision this spring before the next emergence happens. If it's thinning or dying back, you have a removal to plan, and the right time to do that is before it becomes an emergency.

I don't charge for assessments. If you're in Kent, Ravenna, Streetsboro, Akron, Cuyahoga Falls, Stow, Hudson, Aurora, Tallmadge, or anywhere in Portage or Summit County and you want a straight answer about your ash trees, call (330) 221-1617. I'll tell you what I'd do if it were my yard.