Outdoor Services Crew

Thursday, July 30, 2015

EAB (Emerald Ash Borer) on campus

Many state and federal agencies began studying the Emerald Ash Borer (EAB) problem in 2002 when it was confirmed the beetle had arrived in the United States.

How did this beetle arrive in the United States? It has been speculated that the EAB entered on wood packing material on either cargo ships or airplanes that originated in Asia. Over the last ten years, millions of ash trees have died and have been removed in many states across the country as a result of this infestation. 

When it was confirmed the beetle had been detected in Colorado in 2013, arborists at the University of Colorado knew it was just a matter of time before they would discover it on the Boulder campus.... and they did.  Facilities Management Outdoor Services and Housing Facilities Services began steps to save as many of the campus ash trees as possible.

Treatment being done on an ash beside Old Main, critical to CU landscape
About 720 ash trees are actively maintained on the Boulder campus. This year, Outdoor Services, Housing and Dining Services and Parking Services identified approximately 107 ash trees as key elements in landscape designs on campus.  The Main Campus ash trees were the first to receive EAB treatment.  State licensed professionals injected an insecticide directly into the ash tree trunks. Supervising this work, at all times, was a staff member from CU.   Arborist, Vince Aquino, was on hand June 24, 2015, as work began.

The initial step in the treatment process was to identify the first set of ash trees and to set yellow application notice flags at their base.  The flags stayed in place for a week as a means to inform those on campus of the work being done.

Yellow application notices remained for a week at the base of treated trees.
Depending on the diameter of the ash tree trunk, 3 to 4 holes (more if needed) were drilled into the base of each trunk.  Small plugs were then inserted into the holes.  An insecticide was loaded into an insecticide applicator and injected directly into the trunk.   This method greatly minimized exposure to non-targeted animals and/or plants and is very effective in treating the targeted pests--in this case, EAB.

Two insecticides were used in this first round of treatments.  Most trees were protected with Emamectin Benzoate, and a much smaller number of trees received Azadirachtin.  Neither chemical belongs to the Neonicotinoid class.  Campus arborists will monitor the results of these treatments in the coming year.  It is expected that the Emamectin Benzoate treated trees will defend ash trees against EAB infestation for at least two years.

Several holes around the base were drilled into the ash tree.

Plugs were set into the holes.
Diameter of the trunk determined the amount of holes needed.

Tim Kockler, licensed commercial applicator from Davey Tree Expert Company, prepared the applicator.

The insecticide was injected into the trunk of the ash trees

The locations of the first treated ash trees on campus were mapped.  Additional ash trees will be identified and potentially receive treatments next spring.

The University of Colorado is cooperating with numerous state, municipal and federal agencies as part of a Colorado EAB Response Team.  This team is working to improve and to coordinate the  responses to the EAB outbreak all across Colorado.  It is also involved in communicating with the public on management of EAB on private property.

The communities surrounding the University of Colorado have many questions.  People with ash trees in their landscape want to know what to do.  Two great sites for this information are https://bouldercolorado.gov/pages/emerald-ash-borer and https://www.colorado.gov/pacific/agplants/emerald-ash-borer.  The sites help explain symptoms, detection methods and the quarantine guidelines effective since November 12, 2013 for Boulder County and small portions of Jefferson and Weld counties.

Marsha Burch