Walla Walla County confirms invasive emerald ash borer detection

OLYMPIA — Agricultural officials are sounding the alarm following the confirmation of emerald ash borer in Walla Walla County, marking a troubling expansion of North America’s most destructive forest pest in Washington state.

The invasive beetle (Agrilus planipennis) poses a severe threat to the region’s urban canopy and native ecosystems. According to state officials, the pest targets all true ash species, including Oregon ash — the Pacific Northwest’s only native ash tree.

The primary concern for agricultural and forestry authorities is the insect’s unparalleled lethality and rapid spread. A Washington State Department of Natural Resources analysis reveals that without intervention, municipalities risk losing 90 percent to 100 percent of their ash trees within 10 to 12 years of an initial infestation. Nationally, the pest has destroyed over 100 million ash trees since its U.S. discovery two decades ago.

What deepens officials’ concern is the total lack of effective containment options. Eradication has never succeeded anywhere in North America. Because no reliable methods exist to stop an active outbreak, management relies entirely on aggressive preventative measures: removing vulnerable trees, banning new plantings, and enforcing strict quarantines on firewood transportation.

The Walla Walla discovery originated from a local arborist reporting potential damage in College Place. State responders subsequently found larvae and telltale D-shaped exit holes in multiple trees before federal officials confirmed the species on Oct. 14.

State agencies urge residents to inspect local trees, avoid moving firewood, and report any suspected sightings immediately through official state channels.

Photo courtesy Washington State Department of Agriculture

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Elkhorn Media Group