Emerald ash borer (EAB) is one of the most destructive invasive insects in North America, and it has been confirmed in Oregon. While it hasn't reached every neighborhood in the Portland metro yet, it's not a question of if — it's a question of when.
What Is Emerald Ash Borer?
EAB is a metallic green beetle native to Asia. Its larvae feed under the bark of ash trees, destroying the vascular tissue that the tree needs to transport water and nutrients. Infested trees typically die within 3-5 years of initial infestation. EAB has killed hundreds of millions of ash trees in North America since it was first detected in Michigan in 2002.
Do You Have Ash Trees?
Ash trees (genus Fraxinus) are common throughout Portland. They're frequently used as street trees and are found in many residential landscapes. Key identification features:
- Compound leaves with 5-9 leaflets arranged opposite each other
- Bark with a distinct diamond-shaped ridge pattern (on mature trees)
- Opposite branching pattern
- Winged seeds (samaras) that hang in clusters
Prevention Is the Best Strategy
Once EAB symptoms are visible — canopy thinning, D-shaped exit holes, bark splitting — the infestation is advanced and treatment success drops significantly. The most effective approach is preventive trunk injection before the pest arrives in your area.
Trunk injections deliver insecticide directly into the tree's vascular system, protecting it from the inside out. Treatments are typically applied every 2-3 years and have shown high efficacy in protecting treated trees.
Should You Treat or Remove?
Not every ash tree is worth treating. We help homeowners evaluate whether treatment makes sense based on the tree's size, health, location, and value. A healthy, well-placed ash tree that provides significant shade and property value is a strong candidate for treatment. A small, declining ash in a low-visibility area might not justify the ongoing investment.
Take Action Now
If you have ash trees and want to protect them, the time to act is before EAB arrives — not after. Contact us for a PHC assessment and we'll evaluate your ash trees and recommend a treatment plan if appropriate.
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Learn more about how we can help, or contact us to schedule a consultation.