Federal, state and local tree experts are collaborating in preparation for the eventual arrival of the emerald ash borer, a pest that has killed tens of millions of ash trees nationwide.
“It’s really dire,” said Mariah Davis, U.S. Department of Agriculture pest survey specialist. “Emerald ash borers can cause up to 99 percent ash mortality in areas where they’re established.”
These metallic green insects haven’t arrived in Southwest Washington — yet. However, tree surveyors discovered emerald ash borers within Forest Grove, Ore., in June 2022, meaning they must only travel 35 miles to reach Vancouver’s ash trees. Washington officials are currently remaining observant; adult borers emerge from trunks throughout the summer.
Vancouver city officials estimate that nearly 5,000 of the city’s 99,000 trees on public lands are an ash variety, though it’s impossible to know the full extent of the community’s ash population. Schools, hospitals, libraries, other municipal-owned buildings and private properties may be missed in tree inventories.
Planning for pests
Vancouver Urban Forestry crafted a pest management strategy in its draft forestry plan that emphasizes emerald ash borer monitoring and detection. If the beetles emerge, officials will remove dead or dying ash trees, suppress potential spread and replace any lost trees.
Urban foresters and local arborists will implement the Washington Urban Forest Pest Readiness Playbook Assessment, a recently crafted tool to help pest management through self-assessments.
Washington Invasive Species Council outreach coordinator Maria Marlin said the council authored the tool — the first of its kind — in response to the continued threat of invasive pests hitchhiking to the Pacific Northwest. Prevention is the lowest-cost solution to minimizing irreversible impacts to the region’s green infrastructure and agriculture.
“The fundamental existence of cities is based on movement — of people and vehicles — which really increases the risk of hitchhikers coming,” she said. “Once a pest is introduced, they quickly spread to other cities and neighborhoods.”
Climate driving changes
The worsening frequency of invasive species is one of many stressors resulting from climate change. Longer and hotter temperatures help pests expand their range and further damage trees, which may have a lower ability to heal from infestations due to heat stress.
Experts are also monitoring for Asian long-horned beetles that can harm — and kill — more than 40 species of host trees, while spotted lanternflies feast on agriculturally significant crops, namely vineyards and apple orchards. Spongy moths, which are also in Washington, threaten upwards of 500 species of trees and shrubs.
Daria Gosztyla, Washington Department of Natural Resources outreach specialist, said there’s still good news for communities that are preparing for the arrival of invasive pests. By fall, the department will have upwards of $10 million for grants — the most the entity has ever had — to fund community forestry assistance.
As pest outbreaks continue to be a prevalent issue, state and federal agencies intend on hosting seminars and workshops, with the Washington Invasive Species Council expected to host its virtual Urban Forest Pest Summit in September.
