PP&R prepares to manage invasive, destructive pest: Emerald Ash Borer found in metro area

News Article
Members of the public and tree care experts can take measures to slow its spread and protect trees.

(Portland, OR) –

The emerald ash borer (EAB), an exotic beetle that infests ash trees, was discovered in Forest Grove, Oregon on June 30, 2022, marking the first confirmation of the invasive pest on the West Coast. Portland Parks & Recreation’s Urban Forestry team has been working with the Oregon Department of Forestry (ODF), Oregon Department of Agriculture, and community partners, to prepare for this eventuality for the past several years.

An emerald ash beetle, green as its name would suggest, on a tree leaf.
Adult Emerald Ash Beetles are only ½ an inch long (smaller than a dime). Photo courtesy of bugwood.org.

EAB is considered the most destructive forest pest in North America, threatening all species of ash trees. Since it was first discovered in Michigan in 2002, this shiny green beetle has killed more than a hundred millionash trees across the east coast and Midwest. In Oregon in general and in Portland in particular, tree loss in urban areas is continues to be a cause for concern. This threat has the potential to exacerbate canopy loss. The Pacific Northwest’s native ash tree (Fraxinus latifolia) is a very important element of natural areas near Northwest rivers and streams. Once EAB spreads to these ecosystems, it is expected that there will be drastic changes.

What is being done? 

PP&Rs Urban Forestry team continues to work with the Oregon Department of Forestry (ODF), Oregon Department of Agriculture, and community partners on Statewide strategies to help limit their impact.

Some of the actions taken by PP&Rs Urban Forestry team include:

  • Mapping and keeping inventories of ash trees (and other trees) across the City to enhance forest management and protection
  • Removing (in 2019) ash tree species from the City of Portland’s Approved Street Tree Planting List
  • Requiring species diversity in regulated tree planting
  • Joining with ODF in creating the State of Oregon’s EAB response plan.

City Forester Jenn Cairo said diversifying Portland’s canopy is integral in preparing for invasive pests such as the EAB. “This is why we are actively pushing for a diversity in species when we plant and promote tree planting,” says Cairo. “So that when an invasive attacks one species, it does not cause significant harm to the canopy as a whole.”

Portland Parks Commissioner Rubio says she is encouraged by the City’s preparedness efforts. “We know that in Portland, a love of trees is a key part of our shared identity,” says Rubio. “PP&R’s Urban Forestry experts have anticipated the arrival of the emerald ash beetle and have taken initial steps. Once we learn more from the Department of Forestry, we’ll be able to determine additional roles and actions for Portland.”

“We expect involvement from many bureaus and government agencies for a holistic, effective effort,” said Portland Parks & Recreation Director Adena Long. “And we encourage Portlanders to follow the steps recommended to help slow this beetle’s spread.”

Fighting the pest is a team effort

ODF is the lead agency for responding to EAB - but responding effectively requires strategic coordination and communications among many entities which include regional, state and city agencies.  Some of the efforts include the Oregon’s EAB Readiness and Response Plan developed by ODF providing ongoing education and guidance to cities and towns on best practice for slowing the spread of EAB.

ODF has been collecting and saving Oregon ash seeds to preserve for future planting, and to test them for resistance to EAB. In addition to this, ODF has been setting traps across the state to monitor EAB spread.

At the city level, in 2019, Urban Forestry removed ash species from Approved Street Tree Planting Lists. Urban Forestry has ongoing inventories of park trees and street trees. This data provides us with an understanding of where public ash trees are located and potential impact. According to tree inventories are important tools for forest management. By planting a diverse species of trees and avoiding overrepresentation of any tree type, we aim to reduce susceptibility to pests and pathogens.

What can I do, as a member of the public?

Members of the public can play a role in slowing the spread of the EAB by observing the following:

  1. Be on the lookout for EAB
    - Learn how to identify EAB 
    - Learn how to identify ash trees
    - Report any sighting of EAB immediately
  1. Don’t Move Firewood! Firewood can harbor and move insects. If you need firewood, buy it as locally as possible.
  1. Keep ash trees healthy. EAB is attracted to stressed trees. 
    - Keep trees healthy by watering during the summer drought. Water and mulch trees young and mature
  1. Don’t plant any more ash trees (in 2019, they were removed from Portland’s Approved Street Tree Planting Lists)
  1. If you are a local tree care provider, become familiar with signs of EAB. Report sightings and dispose of wood waste properly.

Additional Information:

Questions or concerns: call 503-823-TREE or email trees@portlandoregon.gov

For an EAB fact sheet

For up-to-date information on Portland’s EAB response, please visit Emerald Ash Borer.

For an EAB fact sheet

An essential part of PP&R’s urban forestry work is a strategic, systematic, and targeted approach to tree planting and City partners.

For more information about the important work of PP&R on tree planting please refer to the following resources: 

· Free Street Tree Planting 

· Yard Tree Giveaway 

·Growing a More Equitable Urban Forest: Portland’s citywide tree planting strategy 

·Local Tree Care Providers List – if you are unable to plant a tree on your own, see this list of contractors who may provide this service. 

· Approved Street Tree Planting lists 

Information on tree permits including for tree planting. 

About Portland Parks & Recreation UrbanForestry

The mission of PP&R’s Urban Forestry (UF) division is to manage and care for Portland's tree infrastructure for current and future generations. Portland’s urban forest consists of 220,000 street trees, 1.2 million park trees, and nearly three million private property trees. The Urban Forestry division is involved in managing or regulating these trees.

UF led the creation of and implements the City of Portland's Urban Forest Management Plan, fosters community tree awareness and stewardship, develops tree policies and programs, monitors and assesses Portland’s urban forest, and implements City regulations including issuing permits for planting, pruning, and removal of public and some private trees. During extreme weather at all times of the year, UF crews respond to tree emergencies to keep you safe and the City moving.

Portland has been designated as aTree City USAfor 44 years, aTree City of the Worldand the Urban Forestry program is accreditedby the Society of Municipal Arborists. To learn more about Urban Forestry’s work, check out About Urban Forestryportland.gov/trees/about-urban-forestry