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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 or decline of millions of ash trees in 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. EAB infestation is almost always fatal to infested ash trees, unless 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 reocmmended.
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 lay eggs on the bark of ash trees.
EAB larvae are creamy white in color and are found under the bark, so are not as obvious, but their expanding S-shaped galleries (tunnels) can be located if the bark is removed. Larvae can be located using proper 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 possible presence of EAB in or on an ash trees.
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.
Additionally, in 2014 the Colorado Department of Agriculture established a quarantine for Boulder County and surrounding areas to prohibit the movement of all untreated ash wood and all hardwood firewood out of the quarantined area. The quarantine includes logs and green lumber, nursery stock, wood chips and mulch. Quarantined items may be transported within the quarantined area, but may not be moved outside its borders, and any person violating this quarantine is subject to civil penalties up to $1,000 per violation.
*The Colorado EAB Response Team is comprised of members from the following agencies/organizations: Boulder County, City of Boulder, Colorado Department of Agriculture, Colorado State Forest Service, Colorado State University Extension, Colorado Tree Coalition, Green Industries of Colorado, University of Colorado and USDA Animal and Plant Health Inspection Service.
The Town’s goal is to prolong the life of the healthiest, largest, most significant ash trees in the community, and greatest producers of economic, social, and ecological benefits located on Town-maintained properties. The EAB management strategy for the Town of Erie is to employ a proactive, integrated strategy that utilizes the following management tools:
The CSFS is currently recommending that property owners should consider treatment of desirable ash trees if they are located within 5 miles of a confirmed EAB infestation. The treatment of trees within 15 miles of known infestations may be warranted as infestations spread and are known to occur in several different geographic areas. At this time, treatments will not be administered by Town personnel until EAB has been confirmed within the 5-mile guideline as ill-timed treatment efforts can be a waste of financial and personnel resources and is of no benefit to the tree.
Upon confirmation of EAB within 5 miles of Erie, the Town will initiate an EAB pesticide treatment program that utilizes Integrated Pest Management (IPM) principles to focus on long-term prevention or suppression of pest problems while minimizing the impact on human health, the environment and non-target organisms. The Town is actively budgeting and procuring materials to aid personnel to implement this plan. The Town will not treat any trees located on private property or on Town-owned properties that are not maintained by them, such as areas maintained via Home Owners Associations (HOA) and Metro Districts.
Treatment costs, methods, and efficacy continue to evolve as research progresses on this subject. There are currently four viable insecticide control approaches/methods for use in management of EAB:
The following criteria will be used to determine candidates for treatment priority:
Ash trees already infested with EAB and standing dead trees should be removed to mitigate potential hazards.
The perpetual treatment of smaller trees and trees in poor health is often more expensive than removal. Pro-actively removing trees is safer, more efficient, and less expensive in comparison to removing them once they are fully infested. Residents should consider removing ash trees that meet the criteria listed below: