Monday, August 4, 2014

Emerald Ash Borer Detected in New Areas of Boulder by Christi Lightcap Director of Communications at Colorado Department of Agriculture

BOULDER, Colo. – Emerald ash borer (EAB), a highly destructive tree pest that poses a serious threat to Colorado’s urban forests, has been detected in new locations within the City of Boulder. The non-native pest – already responsible for the death of millions of ash trees and tens of millions of dollars in costs in more than 20 states – is of concern because ash species comprise an estimated 15-20 percent of all trees in Colorado’s urban and community forests.

After EAB was first confirmed in Boulder in September 2013, an interagency EAB Response Team conducted a preliminary survey to determine the extent of infestation. The city was divided into a grid of one-square-mile sections, and branches were sampled from each to determine the presence of EAB. The survey resulted in infestation being positively identified in sampled ash trees within five separate sections.
Recent monitoring efforts have now revealed clear evidence of the pest in three additional grid sections, all adjacent to the original positive sections. A link to the revised grid map can be found at

Mitch Yergert, Director, Plant Industry Division for the Colorado Department of Agriculture and incident commander for the EAB Response Team, says it is important to note that the new locations are most likely detections of previous infestation, as opposed to further spread of the insect.

“Based on the evidence we’re seeing here, these trees were probably infested three or more years ago,” he said. “But we do expect to see some additional spread this summer within the City of Boulder.”

The new detections were possible because of ongoing efforts by the interagency response team, led by the CDA, Colorado State Forest Service, Colorado State University Extension, City of Boulder, Boulder County and U.S. Department of Agriculture Animal Plant Health Inspection Service. The team is working to monitor and contain the spread of EAB in urban ash tree populations.

While City of Boulder Forestry staff have focused ongoing detection efforts adjacent to where EAB has already been confirmed, other agencies and communities continue to monitor for the insect outside the city limits. At this point, no detections have been confirmed outside Boulder.

“For right now, our main focus remains on monitoring for the extent of infestation, educating the public about the threat of emerald ash borer and enforcing the quarantine around Boulder County,” said Yergert.

Because EAB infestations are difficult to detect in early stages and the insect can spread both on its own and via infested wood, the recent detections are not a surprise. New detections are expected to continue, and Yergert says that although the response team does not plan to offer media outreach for every new detection within the City of Boulder, each will be updated on Also, the team will alert the public if the insect is confirmed anywhere outside the city.

EAB: What Coloradans Need to Know

Know how to identify ash trees, and signs of EAB infestation in ash trees:
thinning of leaves and upper branches and twigs
serpentine tunnels produced by larvae under the bark
D-shaped exit holes 1/8-inch wide
new sprouts on the lower trunk or lower branches
vertical splits in the bark
increased woodpecker activity
Don’t apply unnecessary chemical treatments, and talk to a professional forester or arborist before applying any treatment. Chemical treatments are not recommended more than 5 miles from a positive detection.
Never transport firewood or other products from ash trees, as this is the most likely method of accidental spread. A quarantine is now in place in Boulder County and surrounding areas to try and prevent the human-assisted spread of EAB.

For current information about EAB in Colorado, including the current quarantine in Boulder County and surrounding areas, go to If you think you have EAB in your ash trees, please contact the Colorado Department of Agriculture at 888-248-5535 or email