Emerald Ash Borer in Colorado. Now What?


Media Contacts:
Jennifer Bray, Parks and Recreation Communication, 303-441-4160
Sarah Huntley, Media Relations, 303-441-3155

Emerald ash borer pest found in Boulder ash trees; delimitation survey begins Nov. 4

In late September, the emerald ash borer (EAB), an invasive pest of ash trees was identified within the city limits of Boulder. Since that time, staff from the City of Boulder Forestry Division and the Colorado Department of Agriculture (CDA) have worked cooperatively to complete a visual assessment of all public and private ash trees within a half mile of the initial infestation.

Staff visually assessed hundreds of ash trees from the ground, looking for symptoms of infestation, which include large branch dieback in the tree crown, woodpecker damage and excessive sprouting. Fortunately, no obviously symptomatic ash trees were discovered outside of the initial cluster of infested trees, however; EAB is very difficult to detect in early stages.  To determine the full extent of infestation, a delimitation survey begins this week. The survey is being conducted by staff from city forestry, CDA, Colorado State University Extension, and forestry staff from other Front Range cities who have graciously offered to assist. It is anticipated to take up to six weeks to complete.

For the delimitation survey, the city has been divided into plots or grids of one-square mile each. Crews will remove two small branches from each of 10 ash trees near the center of each plot. The branch samples will be peeled and examined closely for the presence of emerald ash borer life stages. The branch sampling protocols were developed by the Canadian Forest Service (CFS). The CFS found by performing random branch sampling on asymptomatic trees with this technique, they were able to detect EAB several miles away from the original location before trees become symptomatic. The goal is to determine the full extent of infestation within the city limits.  The results of the survey will also help guide the future city of Boulder EAB Response Plan to manage the infestation within the city and potentially slow the spread to nearby communities.

On Tuesday, Nov. 5, the city of Boulder is hosting an EAB “tree dissection” for forestry staff from other Front Range cities and Wyoming. Staff from CSU Extension, Colorado Department of Agriculture and U.S. Department of Agriculture, Animal Plant Health Inspection Service, Plant Protection and Quarantine (USDA APHIS PPQ) will be on hand to teach other forestry professionals what EAB looks like and to demonstrate branch peeling techniques to find EAB larvae. More dissections are planned to educate tree care companies.

There are approximately 38,000 city park and public street rights-of-way trees under the jurisdiction of the Boulder Parks and Recreation Urban Forestry Division; approximately 6,000 are ash trees (15 percent of the public tree population).

For more information, please contact the City of Boulder Parks and Recreation Department’s Forestry Division at 303-413-7245.


Media Contacts:
Jennifer Bray, Parks and Recreation, 303-441-4160
Sarah Huntley, Media Relations, 303-441-3155

Emergency quarantine issued for ash trees by the Colorado Department of Agriculture after Emerald Ash Borer beetles found in Boulder

The Colorado Department of Agriculture (CDA) today issued an emergency quarantine in the Boulder County area related to the recent discovery of the Emerald Ash Borer (EAB) beetle in Boulder in late September. The quarantine is effective immediately.

“Our urban trees provide enormous environmental, economic and social benefits to our community, and ash trees contribute greatly to our urban tree canopy,” said City Forester Kathleen Alexander. “We are currently developing a plan to minimize the impact of the highly destructive Emerald Ash Borer to the city of Boulder, and the quarantine is an important step to limit the infestation and slow the spread, which allows other Front Range communities time to prepare.”

The emergency quarantine prohibits the sale and/or movement of all plants and plant parts of ash trees, including but not limited to:

  • Logs and green lumber
  • Nursery stock
  • Chips and mulch, either composted or uncomposted
  • Stumps, roots and branches
  • Firewood of any non-coniferous (hardwood) species (Because ash is difficult to distinguish from other hardwood species when cut into firewood, the quarantine is for all hardwood firewood.)

The following areas are included in the emergency quarantine:

  • Boulder County
  • The entire town of Erie
  • The area extending east from Boulder County to the south including Highway 7, to the north  including Highway 52 and to the east including Weld County Road 7
  • Highway 93 extending south from the Boulder County line to the entrance of Republic Landfill, including the entire landfill property, and including the entire property at 11218 Highway 93 on which the business of the Singing Saw Woodworks is operated
  • The 15-acre, fenced Community Sort Yard located at 8200 Highway 7 in Allenspark, on the Boulder/Larimer county line

Quarantined items may be transported within the quarantined area but may not be moved outside its borders without specific authorization from the commissioner of agriculture or the United States Department of Agriculture. Any person violating this quarantine is subject to civil penalties up to $1,000 per violation. The full text of the quarantine, including additional restrictions, can be found at www.EABcolorado.com.

EAB in Colorado
A suspect ash tree was spotted in Boulder County on Sept. 23 by City of Boulder’s Forestry staff. Insect specimens from the ash tree, located near the intersection of 30th and Iris, were collected and sent to the United States Department of Agriculture (USDA) Systematic Entomology Laboratory, where the identity of the insects was confirmed. The confirmation of EAB in Colorado marks the western-most occurrence of this invasive pest in North America. Colorado is the fourth state to detect EAB in 2013.

Ash trees are popular in Colorado with an estimated more than 90,000 in the city of Boulder alone; the Denver metro area has an estimated 1.45 million ash trees.

EAB general information
EAB is an invasive insect that has been responsible for the death or decline of more than 50 million ash trees in 21 states. It is a small, green metallic beetle, originally from Asia, first detected in North America in 2002 in southeastern Michigan. The emerald ash borer attacks only ash trees and all ash species – including green, white, black and blue – are at risk. Signs of emerald ash borer infestation include a general decline in the appearance of the tree, thinning of upper branches and twigs, loss of leaves, and serpentine tunnels produced by EAB larvae under the bark. Woodpeckers may often be observed removing the bark of infested trees to access the larvae.

It is possible that EAB could infest an ash tree for three or four years before visible signs of decline of the tree. If you suspect your ash tree maybe infested with EAB, residents are encouraged to have it inspected  by a city of Boulder licensed certified arborist , contact CDA at 888-248-5535, or the City of Boulder Forestry office at 303-441-4406.  Infestation signs include:

  • Sparse leaves or branches in the upper part of the tree
  • D-shaped exit holes about 1/8 inch wide
  • New sprouts on the lower trunk or lower branches
  • Vertical splits in the bark
  • Winding S-shaped tunnels under the bark
  • Increased woodpecker activity

How You Can Help
“The public can play a vital role in preventing the spread of this destructive bug by simply not moving firewood,” said Mitch Yergert, CDA’s Plant Inspection Division director. “EAB larvae can survive underneath the bark of ash firewood, and when it’s moved from one place to another, the pest can hitchhike to a new location. Furthermore, it’s important to note that trees begin to decline a bit during fall months but there are certain features of an EAB-infested tree that residents can look for.”

Additional Information


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