‘Profoundly devastating’: Invasive emerald ash borer threatens Oregon trees

Jennifer Killian shows evidence of the bugs on a piece of tree scraping from the Midwest, which she decontaminated with heat treatment, on Aug. 2, 2022. Emerald ash borers leave behind S-shaped marks on the inside of ash bark. (Aliannah Shalikar/High School Journalism Institute)

Jennifer Killian knew the inevitable was coming. She just didn’t know how soon.

As an urban forester for the city of Corvallis, her biggest fear was that the emerald ash borer, an invasive beetle, would be found in Oregon.

“I was telling people, ‘20 years, it’ll be here in 20 years,’” Killian said. “It was already here probably about when I was saying that.”

Oregon experts discovered the invasive species in Forest Grove in late June.

The emerald ash borer, originally from Asia, is predicted to have devastating effects on Oregon’s ash trees, including a species native to the state. Experts say the beetle threatens urban tree canopies and could impact water systems and nursery businesses.

The shiny green beetle, not even the size of a penny, lays eggs beneath the bark of ash trees. The larvae then feed on the tree, cutting sugars off from the roots and starving it within four to five years.

Since its discovery in 2002, the beetle has spread to 36 states. The emerald ash borer is suspected to have arrived in the United States on a wooden pallet shipped internationally, but experts don’t know how it got to Oregon.

Wyatt Williams, invasive species specialist with the Oregon Department of Forestry, believes the pest has been in Oregon for three to five years. Officials are attempting to protect trees by using insecticides, introducing natural enemies and raising awareness. By the time infestations are detected, it is already too late. It is only a matter of time before ash trees across Oregon become infected, Williams said.

The ash borer has haunted Killian across states. She chased the bug in Wisconsin after it was detected there in 2008, helping identify infestations. Now she lives in Oregon and is preparing people here for its spread.

Killian said her husband hates driving with her because she’s never looking at the road. Instead, she’s constantly scanning the trees for signs of infestation, she said.

“I can’t turn it off,” she said. “I’m always thinking about it.”

In Riverbend Park, surrounded by tall, pale ash trunks, Killian explained how the bug will harm around 2,000 ash trees — 11% of the tree inventory — in Corvallis’ public spaces.

After she started working for Corvallis Parks & Recreation in 2017, the city stopped planting ash trees because of the rising concern of ash borers. It will cost just under $1 million to remove all of the city’s ash trees as they become infected, 10 times the city’s annual forestry budget.

“I just know how truly profoundly devastating this will be for Oregon communities,” she said.

The dozens of ash trees in Riverbend Park are safe for now. On a recent summer day, their canopy towered above people walking and riding bikes. In the afternoon, they cast 30-foot shadows over the green lawn where Chad Cooper played with his dogs.

Cooper said he’d be upset if the park’s trees were infested and had to be removed.

“The trees provide oxygen, a source of shade, and beauty,” Cooper said. “If we lose a large number it would be devastating.”

The Oregon ash, native to the state, is at risk of becoming endangered, Williams said. The trees play an important role in stream and wetland ecosystems. Experts theorize their loss could contribute to water temperature increases and impact fish species, he said.

“My heart sunk when I saw it in Oregon ash,’’ Williams said. “I wasn’t surprised; I just knew that it was going to affect a whole bunch of people.”

Nursery owner Tom Epler has stopped selling ash for fear of selling an infected tree and spreading the bug. Epler owns EF Nursery, Inc., outside of Forest Grove, the site of the state’s only known ash borer infestation so far.

“It was a really good seller, and it’s a beautiful tree,” Epler said. “It’s sad that it had to happen.” He expects to lose $50,000 to $100,000 dollars a year by not selling ash trees.

Oregon created an ash borer readiness and response plan in 2018. Scientists don’t know how to eradicate the ash borer, but foresters have been attempting to slow its spread.

The state Department of Forestry also has been collecting ash seeds in order to preserve genetic diversity. Scientists are interested in testing whether seeds can be bred to resist the pest, Williams said.

“I’m optimistic that at least in Oregon, we planned for it. We already got a head start,” Williams said. “All we can do is slow it down. Eventually, it will spread.”

To learn more about the state’s plan for dealing with the beetle, visit oregoneab.info. Learn how to identify the beetle at bit.ly/pestwatch and learn how to identify ash trees at bit.ly/AshEAB.

— Madi Lietz, McNary High School

— Aliannah Shalikar, Liberty High School

This story was produced by student reporters as part of the High School Journalism Institute, an annual collaboration among The Oregonian/OregonLive, Oregon State University and other Oregon media organizations. For more information or to support the program, go to oregonlive.com/hsji.