Emerald ash borer (EAB) is the most destructive tree pest Central Ohio has ever seen. It was first found in the state in February 2003, near Toledo, and has since been confirmed in all 88 Ohio counties — the whole state has been under quarantine since 2010. The containment effort ultimately failed: in January 2021 the USDA ended its federal domestic EAB quarantine entirely, releasing roughly 1,200 counties across 35 states from regulation and redirecting resources to biological control instead. In practical terms, that means EAB is not an outbreak to be waited out. It is permanently part of the landscape here.
For Dublin homeowners, that leaves two live questions: if you still have a living ash, can it be saved — and if you have a dead one, how urgent is it? This guide answers both.
Why Dublin has so much ash
Ash was one of the most heavily planted street and yard trees in American suburbs from the 1970s through the 1990s. It was fast-growing, tolerant of compacted subdivision soil, cheap at the nursery, and it colored up reliably in the fall — so developers and cities planted it everywhere. Those are precisely the decades in which most of Dublin's subdivisions went in.
Where EAB found you depends less on your address than on which kind of ash you have, and Dublin has both kinds:
- Planted ash — the row of matching street or yard trees a builder put in when the subdivision went up. This is the version that hurts a streetscape, because when one species is lined up along a street it comes out of that street more or less all at once. If you are in an established planted-canopy neighborhood — an Muirfield Village, Wedgewood or Llewellyn Farms type of lot — this is the pattern to look for, and matching trees mean matching timelines.
- Woodline ash — native ash that came with the land rather than with the builder, growing mixed into a treeline instead of in rows. On the wooded and riverside lots common in Riverside, Tartan Fields and Jerome Village, these are typically further from the house but harder to reach — and easy to overlook, because nobody walks the back of the lot every week.
The City of Dublin's Forestry Division manages ash in the public right-of-way and in parks; ash on your own property is yours. If you are not certain which trees on your lot are ash, that is the first thing worth settling.
What emerald ash borer does
EAB is a small, metallic-green beetle. The adults are a nuisance to the tree at worst — it is the larvae that kill it. Eggs are laid on the bark, the larvae bore in, and they spend the next year feeding in the thin layer of living tissue just under the bark, carving the winding galleries that give the damage away. That layer is the tree's plumbing. Enough galleries and the tree can no longer move water and sugars between roots and canopy, so it starves from the top down over a few years.
Adults emerge and fly in late spring through midsummer here — the traditional phenological marker is black locust bloom — which is the window when new infestations spread. Unlike most tree problems, EAB is effectively always fatal to an untreated ash. There is no version of this where the tree fights it off on its own.
Warning signs to look for
Start by confirming it is actually an ash: opposite branching (twigs directly across from each other, not alternating), compound leaves of 5 to 9 leaflets, and on a mature trunk, bark in a tight diamond pattern. Then look for:
- Canopy dieback starting at the very top and working down — the earliest reliable sign, and the one to judge treatment eligibility by.
- D-shaped exit holes (~1/8 inch, flat on one side) in the bark. The shape matters; round holes are a different insect.
- S-shaped galleries — winding tunnels packed with sawdust-like frass, visible under loose or splitting bark.
- Woodpecker damage — heavy pecking as birds hunt the larvae, often stripping outer bark to a pale colour ("blonding"). Woodpeckers usually find an infestation before people do.
- Vertical bark splits, sometimes with a gallery visible in the crack.
- Epicormic shoots — new sprouts pushing out of the trunk or root flare, a general distress signal as the tree tries to grow leaves below the damage.
Treat or remove: the 30% rule
This is the part that gets vague answers elsewhere, so here is the actual decision point. The standard professional treatment is a trunk injection of emamectin benzoate, applied by a licensed applicator — in Ohio, chemical tree treatment requires a Commercial Pesticide Applicator license from the Ohio Department of Agriculture, so this is not a homeowner product. University extension guidance consistently puts the practical limit at about 30% canopy thinning: treated trees below that threshold often recover, and documented success rates drop off sharply as dieback climbs past it toward 40%.
| Canopy condition | Realistic call |
|---|---|
| Full, healthy canopy — no visible thinning | Strong treatment candidate. Preventive injection protects a tree that is not yet in trouble, which is by far the best value. |
| Up to ~30% thinning | Still a viable rescue treatment on a structurally sound tree you value. Recovery is likely but not guaranteed. |
| 30–40% thinning | Marginal. Success rates fall steeply through this band; spending here is a gamble. Removal is often the better use of the money. |
| Over 40% thinning, or major dieback | Treatment is not effective. Plan removal — and the sooner the better, for the reasons below. |
| Dead | Removal, prioritized by what it could hit. |
Two things to weigh alongside the canopy percentage. First, treatment is a subscription, not a cure: injections are repeated roughly every two to three years, indefinitely, for as long as you want the tree. Over a couple of decades that is a real number, and it is the part homeowners are most often not told up front. Second, structure matters as much as health. An ash with a full canopy but a badly included-bark union or decay at the base is not a good candidate regardless of what EAB is doing — that is a separate assessment, covered in our guide to tree risk assessment.
Location is the tiebreaker. A treatable ash in the middle of a back lawn is a genuine choice. A treatable ash directly over a bedroom is a choice where the downside of being wrong is much larger.
Why dead ash are urgent — and get more expensive by the season
EAB-killed ash are a special case among dead trees. The wood dries and turns brittle unusually fast, and dead ash are notorious for shedding large limbs or snapping with little of the warning a decaying oak might give. That is a hazard problem, but it is also a cost problem:
- A recently-dead ash can often still be climbed and taken down conventionally.
- Once the wood has gone brittle, climbing it is no longer safe, so the job needs a bucket truck or a crane — a different piece of equipment and a different price. That method is covered on our crane-assisted & tight-access removal page.
- Brittle standing dead in a tight spot, near a roof or utility line, is the most expensive version of the same job. Our Dublin tree removal cost guide covers how access and size move the number.
The practical upshot: waiting on a dead ash does not save money, it costs money — and it raises the risk while you wait. If a dead ash comes down on its own in a storm, see whether homeowners insurance covers tree removal in Ohio, and note that insurers take a dim view of a hazard the owner knew about and left standing.
And when it does not wait for you: a brittle ash that has already dropped a limb on the roof, split over a driveway, or come down across the only way out is no longer a scheduling decision. That is 24/7 emergency tree removal — a different dispatch and a different set of rigging problems, because dead ash under storm load behaves far less predictably than green wood. For wider wind damage and post-storm cleanup once the immediate hazard is gone, see emergency & storm-damage service. If the failure happened in Dublin, remember the city still expects the removal reported to the Planning Director or designee within 48 hours, even though no permit application is required for an immediate danger.
After removal: wood, brush, and what to plant
Ash makes excellent firewood, and since EAB is already established statewide and federal quarantine has ended, keeping the wood on your own property to season and burn is reasonable. Moving firewood long distances is still a bad idea — it is how EAB travelled in the first place, and it moves other pests that are not yet everywhere. Brush and chip disposal in Dublin has its own local rules, including the city's curbside chipper service; see our Dublin brush and yard waste guide. If the stump is staying, grinding versus full removal is the next decision.
On replanting, the one clear instruction is do not replace a monoculture with a monoculture. Avoid Callery and Bradford pear — Ohio has banned its sale as an invasive species and it splits itself apart structurally anyway. Pick something different from what is already lining your street, and match the species to the actual site conditions.
Dublin Tree Pros can inspect your ash trees, tell you honestly whether treatment still makes sense against the 30% threshold, and safely remove any that have become hazardous. If you are not sure whether the tree in question is even an ash, that is a normal question and an easy one to answer on site. Request a free assessment.