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Emerald Ash Borer - EAB - is a highly destructive, non-native insect that infests and kills all North American true ash species (Fraxinus spp.) including green, white, black and blue ash, and their cultivars (including autumn purple ash, a popular white ash varietal in Colorado). The larval stage of EAB feeds under the bark of trees, cutting off the flow of water and nutrients. Infested trees gradually die over a period of approximately two to four years.
This invasive insect has cost municipalities, property owners, nursery operators and forest products industries billions of dollars, and it is responsible for the death of millions of ash trees in at least 25 states and Canada.
An estimated 15% or more of Colorado’s urban and community trees are ash, and many of these trees are located on private property. Ash trees comprise an estimated 15% of the Town of Erie's urban forest, or 11,000 ash trees. Many of these ash trees are quite large and provide significant eco-benefits to the community. EAB infestation is almost always fatal to infested ash trees, unless chemically treated, and infested trees will be dead within approximately four years. EAB is the most destructive forest pest in recorded history.
Once an ash tree is infected, it can become extremely fragile and the likelihood of large branches, or the whole tree, falling onto people or property rises exponentially. Treatment of ash trees or removal of trees is recommended.
EAB adults are dark metallic green in color, with a coppery red or purple abdomen under the wings. The insect is approximately 1/2-inch long and 1/8-inch wide. Adults may be present from late May to September, but are most commonly active and visible in June and July, when they feed on ash leaves and lay eggs on the bark of ash trees
EAB larvae are creamy white in color and are found in the cambium layer under the bark. S-shaped galleries (tunnels) can be located if the bark is removed or when the barks splits as the tree dies Larvae can only be located using destructive branch peeling techniques.
Note that other metallic-green beetles and larval insect stages can be confused with EAB. Talk to a professional forester, arborist, or other tree care professional if unsure about the presence of EAB in an ash tree.
EAB is a strong flier, but adults typically fly less than ½-mile from their emergence tree. Most long-distance movement of EAB has been directly traced to human movement of ash firewood or ash nursery stock. Movement of other untreated ash wood, wood chips greater than one inch, and ash products (green lumber, pallets, etc.) also present a risk.
The inter-agency Colorado Emerald Ash Borer Response Team, comprised of nine agencies/organizations*, is working with partner organizations and communities to help manage the spread and impacts of EAB. Starting in 2013, the EAB Response Team and partners worked to complete an initial survey to determine the extent of spread of EAB in Colorado, and the team continues working with local governments to determine and map the extent of infestation.
The team hosts EAB identification workshops targeting green industry professionals and volunteers and leads EAB education and outreach efforts to inform the media and public. Also, in the fall of 2014, the team released stingless, parasitic wasps that target and kill EAB in Boulder to help control the borer’s spread.
Additional EAB resources and information on how the State of Colorado is handling the disease is available from the Colorado State Forest Service.
The Town’s goal is to preserve the healthiest, largest, and most significant ash trees on Town maintained property. Mature ash trees provide the greatest economic, social, and ecological benefits.. The EAB management strategy for the Town of Erie will employ a proactive, integrated strategy that utilizes the following management tools:
EAB is presumed present in low or undetectable levels throughout Erie. We strongly encourage the public to act now, not to wait until ash trees are dying in their neighborhood. If you'd like to preserve your Ash tree, treat it this year! If you choose not to preserve your Ash tree, budget for removal in the next few years.
The CSFS is currently recommending that property owners consider treatment of desirable ash trees if they are located within 5 miles of a confirmed EAB infestation. As of Fall 2021, this includes the entire Town of Erie. It is appropriate for Erie residents to begin EAB pesticide treatments of worthy ash trees in 2022.
The Town will not treat any trees located on private property or on Town-owned properties that are privately maintained, such as areas maintained via Home Owners Associations (HOA), Metro Districts, and the public right-of-way adjacent to private property.
There are numerous EAB pesticide options available. The most effective are trunk injected emamectine benzoate formulations and must be applied by qualified professionals. All EAB pesticide must be reapplied every 1-3 years based on manufacturers recommendations. Erie Forestry encourages residents to work with a licensed pesticide applicator when utilizing EAB pesticides. Only, licensed pesticide applicators shall apply pesticides to Town owned property. This includes privately maintained public street trees growing in the public right-of-way adjacent to private property.
Residents should consider the following when determining if a particular ash tree is a good candidate for long term preservation utilizing pesticides:
Untreated ash trees will become infested and killed by Emerald Ash Borer. Trees killed by EAB become brittle very quickly and present safety hazards. Dead and dying trees of any species should be removed as soon as possible. Dead trees, especially ash, present a higher risk to the tree removal crew and are usually more expensive to remove than living trees. Residents are encouraged to contact a local licensed arborist to determine the cost of removing a privately maintained tree.
Please be aware: Dead private trees that threaten public safety will receive enforcement action through the Town of Erie’s municipal code. Right – of – way trees are the responsibility of the adjacent property owner.
More information about identifying ash trees can be found here. Site includes information regarding a FREE app developed by CSFS to assist the public with identifying ash trees.