Is Your Ash Tree Worth Saving? A Homeowner’s Guide to EAB Treatment in Waukesha & Burlington

Not every ash tree is worth treating for emerald ash borer. That is the honest answer, and it is the one most homeowners in Waukesha and Burlington need to hear before spending money on a tree that may already be too far gone. The decision depends on four things: how healthy the tree is right now, how large it is, where it sits on your property, and how much canopy you can afford to lose.

If your ash tree still has a full, healthy canopy with less than 30% thinning, is structurally sound, and provides meaningful shade or property value, treatment can absolutely save it. Trunk-injected emamectin benzoate, applied by a certified arborist every two years, is 90% to 95% effective at stopping emerald ash borer (EAB). But if your ash has already lost more than half its canopy, shows heavy woodpecker damage from top to bottom, or has bark splitting with visible larval galleries, removal is the smarter investment.

Key Takeaways

• EAB has been confirmed in all 72 Wisconsin counties. Every untreated ash tree in Waukesha and Burlington will eventually be infested and killed.
• Treatment works best on healthy trees with less than 50% canopy loss. Trees beyond that threshold should be removed.
• Trunk injection with emamectin benzoate every two years is the most effective treatment, achieving 90-95% larval control in research trials.
• Homeowners can self-treat smaller ash trees (under 15 inches trunk diameter) with soil-applied imidacloprid. Larger trees require professional treatment.
• Delaying the removal of a dead or dying ash increases cost and risk. Ash trees become brittle quickly after death, making removal more dangerous and expensive.
• Annual treatment costs for a large shade tree typically run $150 to $300. Removal of the same tree can cost $1,000 to $2,500 or more.

What Is Emerald Ash Borer?

Emerald ash borer (Agrilus planipennis) is an invasive beetle native to northeastern Asia. It was first detected in the United States near Detroit, Michigan in 2002 and has since spread to 37 states and six Canadian provinces. The adult beetles are small, metallic green, and roughly half an inch long. They cause minimal damage on their own.

The destruction comes from the larvae. After females lay eggs in bark crevices, the hatching larvae bore into the inner bark and feed on the phloem and cambium, the thin tissue layers that transport water and nutrients throughout the tree. As larvae feed, they carve serpentine galleries that progressively girdle the tree, cutting off its vascular system. Most ash trees die within three to four years of initial infestation.

EAB attacks all native North American ash species. Green ash, white ash, and black ash are all highly susceptible. Mountain ash and prickly ash are not true ash species and are not targeted.

How to Tell If Your Ash Tree Is Infested

EAB is difficult to detect early because the damage starts high in the canopy and works downward over two to three years. By the time most homeowners notice something is wrong, the infestation is well established. Here are the signs, listed roughly in the order they typically appear.

• Woodpecker flecking. This is often the very first visible sign. Woodpeckers feed on EAB larvae beneath the bark, leaving light-colored patches where they have stripped away outer bark. Flecking usually starts in the upper canopy and progresses downward.
• Upper canopy thinning. Leaves in the top third of the tree become smaller, lighter in color, and sparser. This happens because larval feeding in the upper trunk and branches cuts off nutrient flow to the highest parts of the canopy first.
• Epicormic sprouting. The tree produces clusters of new shoots from the trunk and lower branches. This is a stress response: the tree is attempting to produce foliage below the zone where larvae have severed its vascular system.
• D-shaped exit holes. When adult beetles emerge from the tree in late spring and early summer, they chew small, distinctly D-shaped holes roughly one-eighth inch wide. These are different from the round exit holes left by other boring insects.
• Bark splitting and S-shaped galleries. As infestation intensifies, the bark begins to crack and peel, revealing the serpentine feeding galleries carved by larvae in the sapwood beneath. This is a late-stage sign indicating heavy infestation.

The Decision Framework: Treat, Remove, or Wait

This is the core question every ash tree owner in Waukesha and Burlington faces. The UW-Madison Extension’s guide to evaluating ash trees for EAB treatment outlines the key considerations, and we have adapted them into a practical decision framework below.

Treat If:

• The tree retains more than 50% of its original canopy density.
• The tree is structurally sound with no major trunk defects, root issues, or prior storm damage.
• The tree provides significant value: shade on your home, screening from neighbors, aesthetic contribution, or measurable property value.
• You are willing to commit to ongoing treatment for the foreseeable future (potentially the life of the tree).
• The tree is not creating hazards with its proximity to structures, power lines, or pedestrian areas that would make it a removal candidate regardless of EAB.

Remove If:

• Canopy loss exceeds 50%. Research consistently shows that insecticide treatments are significantly less effective on heavily infested trees.
• The tree is already dead or has large sections of dead, barkless branches.
• Heavy woodpecker damage extends from the canopy down to the lower trunk, indicating larvae are present throughout the tree.
• The tree has pre-existing structural problems (decay, cracks, poor branch architecture) that make it a liability even if EAB were not a factor.
• The tree is in a location where its failure could damage your home, vehicles, or utility lines.

Do Nothing (and Know the Consequences):

• Your ash tree will eventually die. There are no known cases of untreated North American ash surviving an EAB infestation.
• Dead ash trees become brittle faster than most species. Branches and limbs can snap and fall without warning within one to two years of the tree’s death.
• Removal costs increase significantly once the tree is dead because the brittle wood makes the work more dangerous and time-consuming.

EAB Treatment Options Compared

Treatment Method	Active Ingredient	Who Can Apply	Frequency	Best For	Effectiveness
Trunk Injection	Emamectin benzoate	Certified arborist only	Every 2 years	Ash trees of any size needing long-term Emerald Ash Borer protection	Excellent. Industry gold standard for high-value trees
Soil Drench	Imidacloprid	Homeowner or arborist (where legally permitted)	Annually in spring	Smaller ash trees with a manageable trunk diameter	Strong performance on smaller trees, weaker on larger specimens
Basal Bark Spray	Dinotefuran	Licensed applicator or arborist, depending on jurisdiction	Annually	Small to medium ash trees require faster uptake	Good short-term protection with rapid action
Tree Implants	Acephate	Not generally recommended	Annually	Limited use cases due to repeated trunk injury concerns	Lower long-term value due to repeated drilling damage
No Treatment	N/A	N/A	N/A	Ash trees planned for removal or replacement	Near-certain mortality after infestation progression

What Treatment Costs in Waukesha and Burlington

Treatment costs vary based on tree size, treatment method, and the arborist performing the work. Here are the key factors and realistic considerations for the Waukesha and Burlington area:

• • Professional trunk injection (emamectin benzoate):
    Applied by a certified arborist every two years. This is the most cost-effective professional option over time due to its biennial schedule and high efficacy.
  • Homeowner soil drench (imidacloprid):
    Available for purchase at garden centers and applied annually in spring. This is the most affordable option, but it only works reliably on smaller ash trees (under 15 inches in trunk diameter). Efficacy drops significantly on larger trees.
  • Tree removal: Cost depends heavily on tree size, location, accessibility, and complexity. Costs increase substantially if the tree is dead and brittle, located near structures, or tangled with power lines. Stump grinding is an additional service with its own separate cost.
  • Long-term financial consideration: For a mature ash tree with 20 or more years of useful life remaining, ongoing professional treatment is typically more economical than removal and replacement. Removal represents a large one-time expense, while treatment spreads costs over many years. However, if the tree is already declining or poses a safety risk, removal may be the smarter investment to avoid higher costs and hazards later.

• Additional cost drivers:

• • Dead or brittle ash trees require more careful, time-intensive removal techniques.
  • Trees near power lines, homes, or driveways often need specialized equipment and extra safety measures.
  • Permit requirements may vary by municipality; some cities waive fees for removal of diseased or hazardous trees.
  • Stump grinding and debris removal are typically separate line items.

The EAB Situation in Waukesha County and Burlington

EAB is not a future threat in this region. It is here, now, and it has been for years. The Wisconsin DNR’s emerald ash borer tracking program confirms detections in all 72 Wisconsin counties as of 2024. Waukesha County and Racine County (which includes Burlington) have had established EAB populations for over a decade.

In southeastern Wisconsin, ash mortality from EAB has approached 100% in untreated populations. Communities across the region have spent millions removing dead ash from public right-of-ways, parks, and streetscapes. Homeowners who delayed treatment or removal are now facing higher costs as arborists deal with brittle, hazardous dead trees that require more careful (and expensive) removal techniques.

The window for preventive treatment is still open for healthy ash trees, but it is closing. If you have an untreated ash tree on your property in Waukesha or Burlington and it still has a decent canopy, now is the time to act. Waiting another year means more larval damage, less canopy, and a lower chance of treatment success.

When to Start Treatment (Timing Matters)

Treatment timing depends on the method.

• Trunk injection (emamectin benzoate): Best applied between mid-April and mid-June, when the tree is actively transpiring and can move the insecticide through its vascular system. Spring treatment provides protection through the current and following growing season.
• Soil drench (imidacloprid): University research suggests spring application is most effective. Apply when soil temperatures are warm enough for root uptake, typically late April through May in Waukesha and Burlington.
• Basal bark spray (dinotefuran): Can be applied when the bark is dry, typically spring through fall. Uptake is fastest during active growth.

For all methods, treatment should begin before the tree becomes heavily infested. Starting treatment on a tree that has already lost 30-40% of its canopy is still viable, but less likely to produce a full recovery.

What Happens After You Start Treating

Results are not instant. Here is a realistic timeline.

• Year 1: Treatment stops larval development. Existing galleries remain, but new feeding is sharply reduced. Canopy thinning may stabilize or slow, but may not visibly improve yet.
• Year 2: The tree begins to recover. New growth fills in gaps, leaf size increases, and the canopy starts to look fuller. Epicormic sprouts may persist, but should slow.
• Years 3-5: With consistent biennial treatments, most trees show significant canopy recovery. Bark heals over old exit holes and gallery scars. The tree regains structural strength as new wood grows over damaged areas.

Ongoing: Treatment must continue indefinitely, or until EAB populations crash naturally (which may take decades, and is not guaranteed). Skipping a treatment cycle risks re-infestation.

Frequently Asked Questions

Can I treat my ash tree myself, or do I need an arborist?

If your tree is under 15 inches in trunk diameter (about 47 inches in circumference at chest height), you can self-treat using soil-applied imidacloprid products available at garden centers. Larger trees should be treated by a certified arborist using trunk-injected emamectin benzoate, which is more effective on large trees and is not available to homeowners.

How do I know if my tree is an ash?

Ash trees have compound leaves with 5 to 9 leaflets arranged in opposite pairs along a central stem. The bark on mature ash trees has a distinctive diamond-shaped ridging pattern. Branches and buds grow directly opposite each other, not alternating. Mountain ash, despite its name, is not a true ash and is not affected by EAB.

Is it too late to treat my ash tree?

If your tree has lost more than 50% of its canopy, treatment is not recommended. Trees beyond that threshold have sustained too much vascular damage to recover even with insecticide protection. If your tree still has more than half its leaves and the canopy looks reasonably full, treatment is worth considering.

How long do I have to keep treating my ash tree?

Indefinitely. EAB populations in southeastern Wisconsin are well-established, and skipping a treatment cycle exposes the tree to re-infestation. Treatment is a long-term commitment for the life of the tree. With biennial trunk injections, the schedule is manageable and cost-effective.

Will my ash tree fully recover after treatment?

Most trees with less than 30% canopy loss at the time of initial treatment show excellent recovery within two to three growing seasons. Trees that start treatment at 30-50% canopy loss may recover more slowly and may not fully regain their original canopy density, but can still live productive, stable lives.

Does EAB affect any trees other than ash?

No. EAB exclusively attacks trees in the genus Fraxinus (true ash). This includes green ash, white ash, black ash, and blue ash. Mountain ash and prickly ash are not in this genus and are not at risk.

How dangerous is a dead ash tree?

Very. Ash trees lose their structural integrity rapidly after death. Branches become brittle and can snap in light winds. The trunk can fail without warning. Dead ash trees near homes, driveways, sidewalks, or play areas should be removed promptly. Delaying removal increases both the hazard and the cost.

Will my homeowners insurance cover EAB removal?

Generally, no. Most homeowners insurance policies do not cover tree removal due to disease or pest infestation. Insurance typically only covers removal when a tree has fallen and damaged a covered structure. The cost of EAB treatment or preemptive removal is the homeowner’s responsibility.

Is there a city or county program to help with EAB costs in Waukesha or Burlington?

Some municipalities have offered cost-sharing or assistance programs for ash tree removal on public right-of-ways. Contact the City of Waukesha or City of Burlington forestry departments to ask about current programs. Private property treatment and removal costs are generally the homeowner’s responsibility.

What should I plant to replace an ash tree?

Diversify. Do not plant another ash. Good replacement options for southeastern Wisconsin include bur oak, swamp white oak, hackberry, Kentucky coffeetree, honeylocust, and red maple. Choose species that are well-adapted to your site conditions and avoid over-planting any single species on your street or neighborhood.

How many ash trees are in Waukesha and Burlington?

Ash species historically made up 15-25% of the urban tree canopy in many Wisconsin communities. The exact numbers vary by neighborhood, but it is safe to say that thousands of ash trees remain in the Waukesha and Burlington areas, with many still untreated and vulnerable.

Can I use firewood from an EAB-infested ash tree?

Yes, but keep it local. Do not move ash firewood off your property or transport it long distances, as this is a primary way EAB spreads to new areas. If you cut an infested tree for firewood, split it and let it age for two full summers before moving it. After two years of drying, any EAB in the wood will have emerged or died.

Deciding Whether to Treat or Remove Your Ash Tree

The question is not whether EAB will find your ash tree in Waukesha or Burlington. It already has, or it will soon. The question that matters is whether your specific tree is healthy enough, valuable enough, and structurally sound enough to justify the ongoing investment in treatment. For many homeowners, the answer is yes: a well-placed, healthy ash that provides shade, curb appeal, and property value is absolutely worth $100 to $150 per year to protect. For others, the smarter move is to remove a declining tree now, while it is still safe and affordable to do so, and invest in a diverse replacement that will not face the same threat.

Ready to find out if your ash tree is worth saving? Schedule a free evaluation with Rausch Tree and Outdoor Services for expert EAB assessment and treatment options in Waukesha, Burlington, and surrounding communities.