Emerald Ash Borer in Michigan: Can Your Ash Be Saved?
Updated August 2026 · Reviewed by Robert Burgund, ISA Certified Arborist MI-4857A
- Established 2013
- 13+ Years Climbing Experience
- ISA Certified Arborist MI-4857A
- Fully Licensed & Insured
This one is personal geography for us. Emerald ash borer was first found in North America right here, in southeast Michigan in 2002, detected at the same time across the river in Windsor.
Researchers later concluded it had been quietly established since the early-to-mid 1990s. The region has since lost the overwhelming majority of its untreated ash.
What is left is a mix. A small number of trees on protection programs, and a much larger number of standing dead ash that nobody has dealt with yet.
Can this tree be saved?
| Canopy loss | Realistic outcome | What we would advise |
|---|---|---|
| Under 10% | Treatment generally works well | Treat, and stay on schedule |
| 10 – 30% | Diminishing odds. May recover, may not | Assess carefully. On a valuable tree, treatment is a reasonable bet |
| 30 – 50% | Uncertain, but not hopeless | MSU bulletin E-2955 supports treating dieback in the 20–40% range. Worth a real assessment before writing the tree off |
| Over 50 – 60% | Very unlikely to benefit | Removal, and sooner is genuinely cheaper than later. This is where the published guidance says it is too late |
Dead ash does not stay climbable. Research in Arboriculture & Urban Forestry documents structural degradation starting just one to two years after infestation, with branches failing right at the trunk, a failure mode not seen in healthy ash. A tree a climber could have dismantled last year may need a crane this year, and that is frequently a four-figure difference on the same tree.
What treatment actually involves
The effective option for a tree worth saving is a trunk injection of emamectin benzoate.
Research summarized by MSU and the USDA Forest Service shows a single injection reliably protects for about two years and often three. The 2019 edition of the multistate EAB bulletin reports near-complete control for three years from one application. The standard re-treatment interval remains every two years.
Two things to understand before you commit.
It is a subscription, not a purchase. Protection lapses, and one missed cycle can undo years of investment. Budget for it as a recurring cost on a tree you genuinely value.
Early infestation hides well. EAB is often thoroughly established before symptoms show, which means protective treatment sometimes starts on a tree that is already declining. An assessment before the first injection is worth the small cost.
The signs you are looking for
- Thinning from the top down, with dieback starting in the upper third of the crown.
- Water sprouts shooting from the trunk and lower limbs. A distress flare.
- D-shaped exit holes, about 3–4 mm across. The flat-sided shape is the diagnostic detail, because round holes are a different insect.
- Serpentine galleries, which are winding S-shaped tunnels under loose bark.
- Woodpecker flaking high in the tree. A common early tell, though it usually shows in the second year, and woodpeckers chase other borers too.
- Vertical bark splits with galleries visible beneath.
If the tree is already dead
Standing dead ash is the most dangerous routine removal in this trade. The wood fails unpredictably, which rules out climbing, and it fails while people are working underneath it.
Any experienced crew prices a dead ash above a live tree of the same size. A crew that does not is either green or about to take a risk on your property that you would never have agreed to.
Ash questions we hear most
Is it worth treating my ash?
If canopy loss is under about 10 to 20% and the tree is sound and genuinely valuable to the property, for shade or screening or the way the yard looks, then often yes. Past 50 to 60%, the evidence says no. Get it assessed instead of guessing.
How often does the treatment repeat?
The injection protects for about two years, often three. Plan on re-treating every two.
Can I treat it myself?
Soil drenches are sold to homeowners, but trunk injection, the option that actually works on larger trees, takes professional equipment and licensing.
My ash has been dead for years. How urgent is this really?
More than most people think. Brittle ash is dangerous to everyone under it and gets more expensive to remove as it deteriorates. Every season adds risk and cost.
Should I replant with another ash?
No. Plant something else. Hackberry, Kentucky coffeetree and oak are all sound choices here, and tulip poplar works in southern Michigan, though it is only rated to zone 5a and is somewhat weak-wooded.
If you go with an oak, remember the April-to-July no-pruning window. Diversity is the real lesson EAB taught this region.
Get your ash assessed
We will tell you straight whether treatment is worth the money or removal is the smarter call.
Call or Text 248-672-8058Request a Free Estimate
Written and reviewed by Robert Burgund
ISA CERTIFIED ARBORIST · MI-4857A
Owner of Tree Pros, LLC in Bloomfield Township. Verify the certification by name in ISA’s public directory.