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Living Next to Nature: Emerald Ash Borer Management Plan
One of the beautiful things about living in Tigard is being surrounded by nature, from parks and trails to streams and wildlife.
But in a community where humans and animals (in this specific case, insects) live together in an urban setting, there can be challenges that need to be addressed in a holistic way.
What’s the Concern?
The Emerald Ash Borer (EAB) is a beetle of northeastern Asia that was first detected in Michigan in 2002. EAB has decimated the Ash tree population, killing hundreds of millions of trees across the United States and Canada with a 99% death rate with full infestation. It has since arrived in Oregon, first detected in Forest Grove in 2022. Ash trees are a key species for waterway bank stability, keeping water cool, and providing habitat for native plants and animals. The beetle burrows under the bark of ash trees, blocking their flow of water and nutrients until the trees die. Because of the costly impact of EAB, Tigard needed a strategic long-term plan for natural areas with large Ash populations that contain critical infrastructure, are frequented by visitors, and have the potential to become hazards.
What Action is Being Taken to Mitigate the Emerald Ash Borer?
Shortly after EAB was detected in Forest Grove, Tigard partnered with state agencies (ODF, ODA), local governments, and organizations like Tualatin Soil and Water Conservation District (SWCD), Clean Water Services (CWS), and Oregon State University (OSU) to discover best practices and response. Urban forestry experts provided Tigard with a management plan that started with an inventory of Ash trees throughout Tigard.
Upon completion of the inventory within key locations, the City adopted a multi-pronged approach to prioritize sensitive areas and protect infrastructure. These include girdling some trees to draw in and trap EAB, limited strategic pre-emptive cutting, chemical treatment to extend the lives of trees that are particularly valuable due to size and location, and continued monitoring.
The experts and our local, regional, and state partners understand and agree that the management efforts to battle the impact from the Emerald Ash borer cannot prevent attacks and loss of trees. It will only help slow down the extent of the invasion to provide more time and less costly treatment options.
Where Can I Learn More?
These resources linked below are the best places to find up-to-date guidance on what to do within your home, yard or private property.
- Emerald Ash Borer Readiness and Response Plan for Oregon (PDF) - Statewide Collaborative Plan for Oregon
- Emerald Borer Information Network - Managed by Michigan State University researchers and funded by the USDA.
- Emerald Ash Borer in Oregon Resources - Current local information, resources, and maps of EAB detections in Oregon)
- Oregon Invasive Species Online Hotline - The public can help identify signs and symptoms of the emerald ash borer by reporting possible sightings to the Oregon Invasive Species Council’s online hotline.
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