Emerald Ash Borer (EAB) Detected in Fort Collins

Date: May 13, 2020


Emerald Ash Borer Detected in Fort Collins

State and City experts have confirmed the presence of emerald ash borer (EAB) – an invasive, highly destructive pest of ash trees – on the north end of Fort Collins, just outside of City Limits. This detection represents the second detection in the county, and the fourth confirmation of EAB in Colorado outside of Boulder County.

An estimated 15 percent of the trees, or 33-percent of the canopy cover in Fort Collins are ash species. Most of these trees are on private property. EAB attacks and kills both stressed and healthy ash trees and is so aggressive that trees typically die within two to four years after becoming infested. This pest most likely arrived via accidental human transport of infested ash wood, such as firewood or other raw material. A very observant Davey Tree Expert crew first spotted the galleries and exit holes within the canopy of a mature ash tree late last week. City of Fort Collins Forestry Division staff recently inspected and were able to positively identify the pest through signs and gathering samples. The samples were confirmed to be EAB by Entomologists from Colorado State University.

This detection, like the other most recent Colorado detections in Broomfield, Westminster and Berthoud occurred outside of a previously EAB quarantined county. The original State quarantine, which primarily encompassed Boulder County, was established six years ago in an effort to prevent or slow the insect’s spread via the movement of ash nursery stock, firewood, and other wood that may have contained the pest. The Colorado Department of Agriculture (CDA) repealed the Boulder County quarantine through a formal process in December of 2019. The repeal was largely due to the discovery of EAB outside of Boulder County.

EAB was first confirmed in Colorado in 2013, in the City of Boulder. Since then, the pest has been
confirmed in several other municipalities in Boulder County, as well as in Broomfield in late August,
Westminster in September, and Berthoud in October of 2019. In preparation, many Front Range and Larimer County communities have been managing for EAB before its arrival, including Fort Collins, Loveland and Windsor.

Approximately 14 percent of all public-area and street trees within Fort Collins are ash (Fraxinus spp.).
In response to the arrival of EAB, Fort Collins will continue to implement the City of Fort Collins Emerald Ash Borer Management and Response Plan. Since the City’s 2015/2016 budget cycle, the Forestry Division has received funding to selectively remove and replace ash trees in poor condition, shadow plant ash trees that are not planned to be treated long term, evaluate all ash trees on public property and to provide EAB education and outreach to the community. As part of the response plan, the City will start treatments of strategically selected, healthy public ash trees in Spring of 2021.

At this time, City Forestry staff are advising Fort Collins residents and neighborhoods to act now and start implementing their EAB management plans. Residents should first determine if their property has any ash trees, and if so, then evaluate the condition of each tree now and throughout the year. They should also decide whether to have ash trees treated or removed and replaced. City Forestry staff urges residents to weigh the benefits and costs associated with ash removal and replacement versus insecticide treatment over the life-time of the tree.

“It’s important to remember that this is a natural disaster in slow motion,” states Kendra Boot, City Forester. “Since EAB’s first detection in Colorado, we have had the opportunity to plan and prepare for this pest, unlike other parts of the state and country. Like other current challenges, we will approach the management of this invasive pest thoughtfully and thoroughly while balancing the social, environmental and economic impacts that EAB will have on our resilient community.”

EAB as a pest tends to move slowly through natural spread and quickly through human transport. Now that EAB has been detected in Fort Collins, it is important to keep all ash material in Fort Collins and prevent the spread to other communities.

For general public information about EAB please visit fcgov.com/forestry/emerald-ash-borer.

Fort Collins residents with questions specific to EAB management on their property can contact the City of Fort Collins Forestry Division or a Fort Collins licensed tree care company listed at fcgov.com/forestry/arborists.php.

Contact information and other resources are below:
• Fort Collins City Forester: 970-221-6361 or forestry@fcgov.com
• Larimer County Forestry: 970-498-5765
• CSU Extension, Larimer County: 970-498-6000
• Fort Collins Field Office, Colorado State Forest Service: 970-491-8348