Dreaded ash borer arrives in Oregon

Jul 19, 2022 | Author: Larry Mauter, LCSWA member | Editor: Gabriel Bradford

March of invasive pest foretold; allowing forestry officials time to shelter gene pools

The widely reported arrival of the emerald ash borer (EAB) in Oregon is serious news for the valued hardwoods — but it was no surprise.

An effort to save the state’s native ash tree gene pool has been underway for the past several years, according to a release from the Oregon Department of Forestry.

“Since it was first found in the Detroit, Michigan area back in 2002, EAB has become the most destructive and costliest forest pest ever to invade North America,” said Wyatt Williams, the ODF invasive species specialist who is managing the gene-pool effort.

Oregon ash (Fraxinus latifolia) is a deciduous hardwood tree found most commonly in wetlands and along streams, according to the July 11 ODF release.

Leaves of Oregon Ash. Photo by Larry Mauter

The pest was located west of Portland in Forest Grove on June 30, Oregon Public Broadcasting reported. The discovery is the first time the Asian native has been found west of Boulder Colorado, according to OPB.

“It’s an ecologically vital tree as it shades water, keeping it cooler for fish. The roots stabilize stream banks reducing erosion. And lots of animals, birds, and insects eat the seeds and leaves. Losing it will likely have a huge impact on those ecosystems,” Williams explained.

“The first goal is to try and preserve as much of the tree’s genetic diversity as we can before it’s lost,” said ODF’s Williams.

The U.S. Forest Service’s Dorena Genetics Resource Center in Cottage Grove stores the ash seeds and is sharing them with researchers. The researchers will test for any resistance to EAB.

“If any is found, we might then be able to breed resistance into local strains and replant stream banks,” Williams said in the release.

To report sightings of the emerald ash borer, please make a report online at the Oregon Invasive Species Council hotline. View the state’s plan for EAB.

LCSWA member Lee Peterman wrote about the oncoming ash borer in 2019. He had attended a symposium about the ash borer.

“Only 98 percent of the news was bad. The rest was hopeful,” Peterman wrote.

The think-tank symposium was a follow-up to one held a year earlier. Of the six guest speakers, three noted that our Oregon ash was most susceptible of all North American species at a nearly 96 percent mortality rate in test stands.

Watershed councils and foresters should not continue planting thousands of Fraxinus Latifolia, as those stands will become both a source of food as well as a highway for the infestation to travel and spread even more quickly, Peterman argued.

The clear and oft-repeated theme from nearly all the speakers, he explained, was to urge greater diversity in riparian areas and forested land.

One strategy that Peterman developed in managing his 80-acre woodlands plot was to plant black walnut trees in areas normally seen as good habitats for ashes.

Emerald Ash Borer
Emerald ash borer shows off its characteristic abdomen. Photo credit to Backyard Habitat Certification Program

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Emerald ash borer shows off its characteristic abdomen. Photo credit to the Backyard Habitat Certification Program