Emerald ash borer pops up in more new places, including first detections in Beaverton, Salem and Rockcreek

BEAVERTON, Ore. – Emerald ash borer (EAB), an exotic beetle that infests and kills ash and olive trees, has been confirmed for the first time inside Beaverton, Salem, at Bethany Lake Park in the Rockcreek area, as well as at the Oregon Garden in Silverton. EAB was also detected along the Banks-Vernonia State Trail, marking the first time EAB has been found in an Oregon state park.  Jackson Bottom Wetlands Preserve in Hillsboro also reports it has likely found EAB there for the first time. That report is awaiting official confirmation from the state.

The beetles were found when traps set out this spring were checked in July.

In addition, EAB was found again in the same school parking lot in east Portland where it showed up last summer, as well as reappearing in Hazeldale Park west of Beaverton.

EAB was found in Forest Grove in Washington County in June 2022, making Oregon the first state on the West Coast to report an infestation. Since then it has been found in four other counties in the Willamette Valley – Clackamas, Marion, Multnomah, and Yamhill.

Salem

The City of Salem has been preparing for the arrival of emerald ash borer in the city for several years. An important first step was conducting an inventory of street, park and natural area ash trees. Salem identified nearly 4,000 ash trees along streets, in parks, and in over 400 acres of natural areas with a high density of ash. The City also has:

• Created management plans for identified ash trees on City-owned property
• Created and published an Emerald Ash Borer Readiness and Response Plan (https://www.cityofsalem.net/community/natural-environment-climate/trees-and-plants/emerald-ash-borer)
• Halted the siting and planting of new ash trees
• Begun preemptive removal of ash trees in poor health
• Injected insecticide into around 1,200 ash trees identified to be in good health to protect them from EAB
  • These injections began in summer 2025 with 600 trees in the northern part of the city receiving injections last year, and another 600 trees to be injected next spring. This process is highly effective at killing EAB and keeping trees alive through their natural lifespan if treatment is started before trees are damaged and continued every 2-3 years.

The City of Salem will continue to carry out other work to mitigate and contain EAB, including:

• Underplanting in natural areas around ash trees
• Replacing removed ash trees along streets and parks with a wide variety of other species to add resilience and diversity to the urban canopy
• Providing education and outreach about EAB through social and print media and at community events.

Learn more about Salem’s response plans here.

Beaverton’s response

Beaverton’s Urban Forestry team was spurred by EAB detections in places just west of the city over the past few years to start preparing in earnest. Beaverton received a one-year grant from the Tualatin Soil and Water Conservation District in October 2024 to help with EAB mitigation. During the 2025 treatment season the Beaverton Urban Forestry team used the grant’s funds to treat 600 of the 2,000 inventoried ash street trees, with plans to protect a further 600 soon. Beaverton has also planted 60 new street trees with the help of volunteers and Friends of Trees.

“In response to the threat of EAB, in 2026 we have so far treated 22 city-maintained natural area trees 20 inches in diameter and larger and planted over 2,000 native trees and shrubs,” said Beaverton City Arborist and Public Works Supervisor Jered Lane. “We are continuing to monitor ash street trees throughout the city with regular inspections, respond to concerns about possible cases in Beaverton, and educate the public about EAB.”

Advice for cities and homeowners

One immediate step cities should be taking is to stop planting ash and olive trees and if they haven’t already to remove them from their list of approved street and yard trees.  The second is to make sure City staff who work with trees know how to identify an ash or olive tree. A PowerPoint on how to do that can be found at https://www.oregon.gov/odf/forestbenefits/Documents/identifying-ash-trees-march-2023.pdf

If you think you’ve seen an emerald ash borer, the Oregon Dept. of Forestry (ODF) and Oregon Dept. of Agriculture ask that you first make sure it’s not a common look-alike bug.

“Keep in mind that EAB adults are only around from June through September. You can find a good description and photos comparing EAB to other common insects in Oregon that are also green in color at OregonEAB.com,” said ODF EAB Specialist Kat Bethea. “If you can capture the beetle in a jar or other container that’s ideal, but at least try and take a clear, close-up photo. This helps us identify the insect in question much more easily.”

Bethea said people suspecting they’ve found EAB should report it over the phone to 1-866-INVADER or online at https://oregoninvasiveshotline.org/reports/create. Attaching a clear photo is important. Bethea said people who know they have an ash tree and notice a decline should report it the same way.

“Any ash tree can be infested, including native Oregon ash as well as non-native street, park and yard trees. Signs of infestation include thinning and yellowing leaves, bark splitting, D-shaped holes in the tree bark, and shoots from buds on the trunk or branches,” said Bethea.

Matt Mills, who is also an EAB Specialist with ODF, said, “You can find whether or not you’re in an EAB-infested area or close to one by checking an online map we’ve created. It shows the five counties where firewood from hardwood trees cannot be removed. That quarantine also covers any part of ash, olive or white fringetree (Chionanthus virginicus).”

People who want to protect their ash trees before they become infested should consider the same treatment Beaverton, Portland, and Salem are using to protect their high-value public ash trees. “The insecticide is injected at the base of the trunk and gets taken up into the tree canopy and is quite effective at protecting the tree from both adults and larvae,” said Mills.

Mills said treatments must be done before trees are damaged and repeated every two or three years by a licensed pesticide applicator.

“That’s why we recommend only treating high-value trees in good condition,” he said. “Ash trees planted in the wrong place to reach their mature size, such as under powerlines, should be removed as time and funds permit and replaced with species that aren’t susceptible to EAB.”

Homeowners might also consider replacing young ash trees while they are still small and starting over by planting a species that is not susceptible to EAB.  “This gets new tree canopy jump-started in urban areas where ash trees will be lost if not treated,” Mills said.

America’s most destructive forest pest

Since it was first found in Michigan two decades ago, EAB has become the most destructive forest pest ever seen in North America. Where they spread to, EAB larvae eventually kill almost all ash trees by feeding on the living tissues under the bark. Oregon ash and all other American and European ash species are susceptible. The insect is devastating ash stands from the Atlantic Ocean to the Rocky Mountains. Hundreds of millions of ash trees in the U.S. and Canada have already been killed by EAB.

For more information visit the Oregon Invasive Species Council EAB web site at  www.oregoneab.com

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