Emerald ash borer, known for wiping out ash trees, discovered at 3 Oregon sites

One of the most destructive invasive insects in the United States has been detected in three more Oregon counties this summer, which could be bad news for the state’s ash trees.

Federal and state officials said Monday the emerald ash borer, known for killing 99% of Michigan’s ash trees and killing thousands more across the East Coast, has been detected in Yamhill, Clackamas and Marion counties.

The small metallic-green beetle, native to eastern Asia, was first found in Oregon in Forest Grove in June 2022. Since then, extensive testing has taken place to attempt to limit the species damage in Oregon.

“No state has been able to eradicate EAB, so since its first detection in Forest Grove, we have expected it to eventually show up in new parts of Oregon,” said Cody Holthouse, the compliance and regulatory manager at the Oregon Department of Forestry. “That’s why folks from collaborating agencies have been methodically surveying for the insect, setting out traps beyond the known infestation area and training people to know the signs and symptoms of infestation. That definitely helps us learn where the insect is spreading.”

Once detected, officials quarantine the area.

Officials are working out the details of a quarantine to limit the movement of ash, olive and white fringe tree wood, and other materials similar to the one in Washington County.

That quarantine restricts the movement of several tree materials, including but not limited to logs, green lumber, nursery stock, scion wood, bud wood, chips, mulch, stumps, roots, branches, and firewood of hardwood species.

“We want to protect the rest of Oregon for as long as possible to give communities more time to prepare,” said Holthouse.

To slow further spread, Holthouse urges Oregonians to buy firewood near where they intend to burn it and avoid taking firewood more than 10 miles from where it was cut.

How do emerald ash borers impact trees?

The emerald ash borers' larvae burrow into the bark of ash trees, causing canopy dieback and, ultimately, tree death. The half inch beetle is often challenging to detect, especially in newly infested trees.

“Signs of infestation include thinning and yellowing leaves, bark splitting, D-shaped holes in the tree bark, and basal shoots,” a news release said.

Suspected emerald ash borer infestations can be reported over the phone at 1-866-INVADER or online at oregoninvasiveshotline.org/reports/create

Here are the locations of where the bug has been located, according to a news release from ODF.

Yamhill County

One adult beetle was found in a trap in the Gaston area. A federal lab officially confirmed the find as an emerald ash borer on Aug. 12. The trap was located just inside Yamhill County about 7 miles from Forest Grove, where the emerald ash borer was first detected in Oregon in late June 2022.

Clackamas County

Jake Downer, a contract worker with Portland General Electric, reported to the state seeing ash trees in the Elliot Prairie area east of Woodburn showing canopy decline in mid-July, not long after he and other utility workers had received training from the Oregon Department of Agriculture for how to identify emerald ash borer infestations. The site is inside Clackamas County, not far from the border with Marion County.

Wyatt Williams, ODF’s invasive species specialist, visited the site in early August. He saw evidence that emerald ash borer larvae had been feeding on Oregon ash trees , with several trees showing a marked decline. Samples have been sent to the federal lab in the eastern U.S. for official confirmation.

Williams also looked at several ash trees in a steep, blackberry-choked site along Butte Creek north of Mt. Angel and south of Hubbard. The creek forms the border between Clackamas and Marion counties. He said the trees on both sides of the creek showed strong signs of emerald ash borer infestation, with declining canopies and D-shaped exit holes where adults have tunneled out of the tree trunks.

“The extent of dieback suggests that EAB may have been present for a number of years at the site but went unnoticed given the difficult access and dense vegetation, which includes a mix of oak and conifers,” said Williams.

Marion County

On July 30, Williams found adult emerald ash borers in traps set along the Pudding River south of Woodburn and west of Mt. Angel. He retrieved five adults from a trap at that site, indicating a significant population. Samples from that site have also been confirmed as emerald ash borer by USDA APHIS’s lab.

“Given the trees did not show any signs of damage, we would not have known about this site for some time if not for the traps,” said Williams.

Holthouse said ODA will be conducting intensive searches in the coming days for emerald ash borer in areas surrounding the new sites in Marion and Clackamas counties to find out whether it shows up farther away.

Zach Urness has been an outdoors reporter in Oregon for 16 years and is host of the Explore Oregon Podcast . Urness is the author of “ Best Hikes with Kids: Oregon ” and “ Hiking Southern Oregon .” He can be reached at zurness@StatesmanJournal.com or (503) 399-6801. Find him on X at @ZachsORoutdoors.

This article originally appeared on Salem Statesman Journal: Emerald ash borer, known for wiping out ash trees, discovered at 3 Oregon sites