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Environment / Sustainability

CSU can help you watch your ash

July 29, 2014

With the recent announcement that emerald ash borer (EAB) has been detected in additional ash trees in Boulder, Colorado State University experts are offering resources to help protect trees from the destructive pest.

EAB adults have an emerald-green head/back and coppery reddish purple abdomen. Photo: David Cappaert, Michigan State University

EAB was first confirmed in Colorado last fall, in the city of Boulder. The beetle, which is native to Asia, is responsible for the death or decline of tens of millions of ash trees in more than 20 states, and threatens all true ash species (genus Fraxinus).  As a result, the non-native insect poses a serious threat to Colorado’s urban forests, where ash species represent an estimated 15 to 20 percent of all trees.

Experts from CSU Extension, the College of Agricultural Sciences and the Colorado State Forest Service are part of an interagency response team that is managing the pest in Colorado.  Other members include representatives from the Colorado Department of Agriculture, U.S. Department of Agriculture Animal and Plant Health Inspection Service, and the city and county of Boulder.

The team’s goals are to monitor and contain the spread of EAB in urban ash tree populations. So far, the pest has not been detected outside the city of Boulder.

Below is more information about how CSU can help.

Colorado State Forest Service

The Colorado State Forest Service is working to secure federal grant funding to help communities prepare for EAB and plan for the next-generation urban forest. And to help homeowners and communities make decisions about dealing with EAB, the CSFS has released a Quick Guide about EAB in Colorado:

Adult emerald ash borers are approximately 1/2-inch long. Photo: David Cappaert, Michigan State UniversityThe CSFS is providing critical leadership and communication assistance in the EAB response effort. Keith Wood, CSFS community forestry program manager, serves as the interagency EAB Response Team’s primary contact for Colorado communities and municipalities dealing with the potential insect threat. He presents at numerous workshops to help educate Colorado communities, urban foresters and others about EAB. Wood also serves on the Colorado Tree Coalition’s Emerging Pest Issues in Colorado (EPIC) committee, a statewide forestry group that educates foresters about problems on the horizon. Ryan Lockwood, CSFS public and media relations coordinator, also has recently assumed a key role as lead information officer on the interagency response team. 

CSU Bioagricultural Sciences and Pest Management

Renowned CSU Professor of Bioagricultural Sciences and Pest Management Whitney Cranshaw has been responding to the problem of EAB in Colorado even before the discovery last fall. With an Extension appointment, his responsibilities primarily involve outreach activities related to diagnosis and management of insect pests, working with local county Extension agents, staff and volunteers.

Emerald ash borer larva. Photo: David Cappaert, Michigan State UniversityCranshaw has been a key spokesperson and invited speaker at a variety of venues to discuss the presence, potential migration and mitigation of EAB in Colorado. Since its discovery in Boulder last fall, he developed a 17-page control options guide that can be found at The guide addresses the potential damage caused by EAB and when/how control measures are appropriate.

Tamla Blunt, research associate with the Department of Bioagricultural Sciences and Pest Management, is offering another valuable form of outreach. Working with Boulder County Extension, she has developed online videos to show ash tree owners:

Also, keeping up with new or suspected EAB finds is Professor of Bioagricultural Sciences and Pest Management Boris Kondratieff, renowned taxonomist, who provides identification of submitted insects for official confirmation or elimination as EAB.

CSU Extension

 Colorado State Forest Service and CSU Extension personnel identify EAB in the branch of an ash tree. Photo: Ryan Lockwood, CSFS

CSU Extension Agent Carol O’Meara has been on the ground working in Boulder County since day one of the discovery of EAB in Boulder.O’Meara works as part of the county’s EAB response committee, which commissioners formed to develop a comprehensive plan to deal with the pest. Like Keith Wood from the CSFS, she serves on the EPIC committee. Read more about how O’Meara has helped respond to this destructive pest at

Micaela Truslove, program associate in horticulture at the Broomfield and Boulder County Extension offices, has developed an EAB manual for front-line responders and landowners, which can be found at Also, Extension staff from nine counties, working with the Department of Horticulture, spent tireless hours peeling bark off ash branches to help determine the extent of the insect’s spread. Between November 2013 and January 2014, staff peeled and evaluated 846 branches, representing 423 trees.  They continue to survey trees, respond to citizen concerns, and formulate strategies to slow EAB’s spread.  

EAB: What All Coloradans Need to Know

Vertical splits in the bark are one of the signs that EAB has infested the tree. Photo: Joseph O'Brien, International Society of ArboricultureLearn how to identify ash trees, which have the following features:

  • diamond-shaped bark ridges
  • compound leaves with 5 to 11 leaflets
  • leaflets, buds and branches growing directly opposite from one another 

Be able to recognize signs of EAB infestation:

  • thinning of leaves, upper branches and twigs
  • serpentine tunnels under the bark
  • D-shaped exit holes about 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.This is the most likely method of accidental spread.

Ash trees comprise an estimates 15 to 20 percent of all trees in Colorado cities, neighborhoods, parks and backyards. Photo: Colorado State University Facilities

For current information, go to If you think you have EAB in your ash trees, contact the Colorado Department of Agriculture at 888-248-5535 or email 

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