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Emerald Ash Borer FAQ
Frequently Asked Questions about Emerald Ash Borer (EAB)

What are the symptoms of EAB?

The most common signs of an EAB-infested ash tree are: Blonding of ash bark.jpg
  1. High level of woodpecker feeding activity (bark flecking or "blonding")
  2. Thinning canopy and dieback
  3. Bark cracks and splitting

You are NOT likely to see an adult EAB (beetle). However, you may see an EAB larva if you look beneath the bark of an infested ash tree.

How does EAB kill ash trees?

EAB beetles are more attracted to stressed ash trees than healthy ash trees, most likely because the stressed ash tree has less chemical defenses against insect predators. Once a suitable ash tree is located, the female EAB beetle lays its eggs on the bark surface. As the larva hatch from the eggs, they crawl beneath the outer bark and begin feeding on the inner bark. The inner bark (phloem and cambium) transports water and nutrients throughout the tree. Eventually, as the EAB infestation grows, the larva eat so much of the inner bark that the tree essentially dies from a lack of food and waterEAB typically kills ash trees within 2 to 5 years. 

If an ash tree has EAB, can it be saved?
Evidence of emerald ash borers
Depending on the size and health of an ash tree, it may take anywhere between 2 to 5 years for a tree to die from an EAB infestation. However, an EAB infestation needs to be identified early in order for a tree to be treated and saved. Once an infested ash tree has lost about 30% or more of its canopy, it is unlikely to recover even with treatment.

What kinds of ash trees are killed by EAB?

All "true" ash trees of the Fraxinus genus are vulnerable to attack by EAB. In Minnesota, these trees include: Green Ash (Fraxinus pennsylvanica), Black Ash (F. nigra), and White Ash (F. americana). Mountain Ash (Sorbus spp.) is not a true ash and is not attacked by EAB.

Emerald ash borer attacks ash of different sizes from as small as one inch diameter to large mature trees. They commonly attack stressed and unhealthy trees first, similar to the native bronze birch borer and two-lined chestnut borer. However, unlike these insects, EAB will also successfully attack vigorously growing trees.

What can I do to protect my ash trees?

First, keep your trees healthy by properly watering and pruning them. Try to avoid pruning during the growing season. Second, watch your ash trees for signs of infestation. If you notice these signs, contact the City forester or a tree care company with a certified arborist on staff. An appropriate pesticide treatment can protect ash trees from EAB, but the treatment must happen either before or during the early stages of infestation.

For more detailed information on insecticide recommendations, visit or call the Burnsville Forestry Department at 952-895-4508.

Who can perform the pesticide treatment?

For private trees, the City-allowed methods include trunk injection (recommended), soil injection, spraying, and soil drenching. However, soil drenching is not allowed for boulevard (right-of-way) trees and is not recommended for private trees because of environmental concerns. 

While some pesticides are available for retail sale, others may only be purchased and applied by a state-licensed commercial pesticide applicator. The Minnesota Department of Agriculture (MDA) recommends that property owners ask to see an applicator's identification card and verify that the license is current and includes turf and ornamental licensure before allowing any application work on their property. Property owners may also contact the MDA at (651) 201-6615 to verify proper licensing. You can also check the MDA Online Licensing System.

Also, any individual or company hired to do tree work (including pesticide work) in Burnsville, must be licensed by the City as a tree contractor -- you can find the City-licensed tree contractor list here.

How much does the pesticide treatment cost?

The cost of treatment to protect an ash tree from EAB varies based upon pesticide, application method and tree size. Typical cost can range anywhere from $50 to $200, and some treatments last two years or more. Burnsville residents may take advantage of City contract pricing for EAB treatment for ash trees. Visit the main EAB page for more info.

How can I select a good tree care company?

Avoid door-to-door salesman and stick with reputable, established firms. The City of Burnsville has a  List of Licensed Tree Contractors that are licensed to do tree removal, trimming and/or injections. The City has evaluated these companies to make sure that they are properly insured and have an ISA-Certified Arborist on staff. If you're hiring a company to treat your ash tree, make sure that they have a valid commercial pesticide applicator license from the Minnesota Department of Agriculture.

Should I be planting or removing ash trees?

Because of the overabundance of ash in urban landscapes and other sites, it is strongly recommended not to plant additional ash. Consider planting other tree species, especially native trees that are well adapted to Minnesota climate conditions. However, if you have an ash in your yard and it is healthy, it is not necessary to remove it. Instead, consider planting a tree adjacent to your existing ash to avoid a drastic loss of shade if and when your ash tree dies. Burnsville maintains a list of recommended tree species.

What is the City doing to prepare for EAB?

In April 2013, Burnsville's City Council approved an updated Emerald Ash Borer Plan that dedicates $3.5 million over 10 years to help protect some existing ash trees on public property, to remove others that become infested, and to plant new trees of different species.

The City has approximately 3,000 ash trees in its boulevards, 930 in parks, and 14,300 in public woodlands. There are also more than 22,000 ash trees found on private property. The dedicated funds will allow the City to treat good quality ash trees in parks and boulevards to protect them from EAB. The funds also cover the removal of poor condition ash trees on public property and the planting of new tree species.

Ash trees in unmanicured woodland areas of parks will not be treated against EAB or removed unless necessary for safety reasons. Trees on private property will not be part of the City’s treatment or removal plan.

What else can I do to help prevent the spread of EAB?

Adult emerald ash borers can only fly about one quarter mile per year, so the natural spread of the destructive insect is slow. However, humans have helped EAB spread by moving infected firewood and other wood products from an infested site. Do not move firewood—even if you intend to burn it promptly. The insects can escape from the wood quickly and infect new sites. The best prevention is to keep EAB contained.

What are those Purple Boxes?EAB Trap in Burnsville Park

Residents may notice purple EAB traps hanging from ash trees in local parks. The Minnesota Department of Agriculture places these boxes to help with detection of new EAB infestations. The three-sided traps give off a scent that attracts nearby EAB beetles -- when the beetles land on the trap, they become stuck. The earlier an EAB infestation is identified, the better chance we have of eliminating that infestation.

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