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Emerald ash borer. Courtesy

CHEYENNE – Several dozen locals turned out to the Laramie County Library on Thursday to learn more about the emerald ash borer, a beetle that has devastated ash populations from the Midwest to Longmont, Colorado.

Three speakers addressed the crowd of about 60 people, starting with Ryan DeSantis, forest health program manager for the Wyoming State Forestry Division. DeSantis said that while the emerald ash borer – EAB for short – has not yet been detected in Wyoming ash trees, it’s likely only a matter of time before it does show up here.

Named for its adult coloration – an iridescent green carapace – it’s the larval form of EAB that causes the real damage to ash trees. They feed beneath the bark of the tree, leaving distinctive snake-like patterns, as well as capital D-shaped holes when they finally emerge from a tree.

DeSantis said infested firewood is the most likely explanation for how EAB migrated from its “ground zero” in Michigan to Colorado. He said careless firewood transportation will likely be what brings the beetle to Wyoming as well.

But DeSantis noted that Wyoming’s far-flung geography could prove effective in limiting the spread of EAB, provided people are careful about transporting their firewood.

“Resource limitations are what could potentially limit it here,” he said. “The gypsy moth was found in Wyoming in 2015 and 2016, but it really didn’t spread anywhere because there was nowhere for it to go. Most of the populations of ash are in towns and cities, which are fairly good distances apart.”

Even so, Micaela Truslove, an urban forestry technician in Boulder, Colorado, said that’s no reason for cities in Wyoming not to begin planning for EAB. Truslove said her community has been dealing with the beetle since it was confirmed there in 2013, and even that was due to a bit of luck combined with proactive testing.

“We found it because we were looking for it; Boulder changed its monitoring protocols because we knew it was coming; and as it happened, the first tree we sampled had EAB,” Truslove said. “We were sampling all trees that were under a removal contract, and we found adults stuck in the bark. We think they were there as early as 2008.”

Once the beetle first arrives in a community, Truslove said that community has about eight to 10 years before ash trees start dying en masse, and the acceleration can be brutally swift. She showed images of some affected trees in front of a University of Colorado, Boulder, housing complex that had gone from fairly healthy in 2014 to completely dead by late last year.

But early detection can also be difficult and time consuming, especially for smaller cities with only a handful of urban forestry staffers. Such was the case in Boulder, where Truslove recalled one suspect tree had to be sampled eight times before EAB was finally found.

She said that pesticides can be helpful for saving healthy trees, but even then they only work for three years at a time. In a case like Boulder where many trees have been infested, Truslove said pesticides do less to save trees and more to buy extra time so that city staff aren’t completely overwhelmed by the effort to remove dead ones.

“Our long-term plan is to treat 25 percent of Boulder’s ash trees on a three-year rotation,” Truslove said, and as for the rest, “We have about 180 trees coming down this winter, on top of about 450 we’ve removed so far.”

Mark Ellison, assistant director for Cheyenne Urban Forestry, said the city has already been testing branches of distressed ash trees and has not yet turned up any signs of EAB. In the meantime, his department is going to begin compiling its own EAB management plan to determine which trees to save and how, once EAB does arrive here.

“One program we’re going to get started soon is a neighborhood tree-planting program,” Ellison said. “We’ve already been losing a lot of cottonwood, a lot of elms, and people just aren’t replanting these trees, so we’re hoping to do fundraising and get a lot of community support for that.” 

In the meantime, he encouraged private residents to consider planting non-ash tree species if they do plan to plant anything.

“And watch your ash trees closely. If you think something is wrong with them, call one of our licensed arborists, let them come and diagnose the issue,” he said, tempering that with, “We had a nasty freeze in November of 2014 that hit our ash and elm population hard, and we’ve gotten called to trees that are dying or dead, but we aren’t finding EAB.”

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