PORTLAND, Ore. (KOIN) – The Oregon Department of Forestry spent three years collecting more than 900,000 seeds from populations of Oregon ash trees throughout the state.
The ODF employees completed their collection work months after the emerald ash borer, an invasive insect that’s known to decimate ash tree populations, was first discovered in the state.
The emerald ash borer was found in Forest Grove on June 30, 2022. This was the first time the insect had been seen on the West Coast.
The emerald ash borer is considered the most destructive forest pest in North America and has been detected in 34 other states. These invasive and destructive beetles have killed up to 99% of the ash trees in some North American locations. At least five ash species native to the Central U.S. have become critically endangered as the emerald ash borer spreads across the country.
Knowing it could only be a matter of time before the insect arrived in Oregon, ODF staff started collecting ash tree seeds before the insect had a chance to wipe the trees out.
“We learned from our counterparts that almost all the native ash in infested areas in the eastern half of the country were killed within 10 years or so after the arrival of the invasive emerald ash borer,” said Wyatt Williams, ODF invasive species specialist.
ODF received a federal grant from the U.S. Forest Service to do the seed collection work.
The seeds were collected from 245 mother trees that represent 27 distinct populations. They came from areas including the Coast Range, the Willamette Valley, the western Cascade foothills and in areas near the California border.
The collected seeds were cleaned and sorted at ODF’s JE Schroeder Seed Orchard facility in St. Paul. A third of the seeds were sent to a long-term storage facility at the Center for Agricultural Resources Research National Seed Lab in Fort Collins, Colo.
Another third was sent to the U.S. Forest Service’s Dorena Genetic Resource Center in Cottage Grove, and to the U.S. Department of Agriculture’s Agricultural Research Service’s North Central Regional Plant Introduction Station in Ames, Iowa. These two sites will help facility research on Oregon ash, the only species of ash native to the state.
“Researchers can plant some of the seeds in areas where emerald ash borer is present in significant numbers and see if any of the seedling trees show resistance to the insect,” Williams said. “If some trees survive, those resistant trees could become the basis for reintroducing the species to western Oregon. Resistant trees would be crossed with other Oregon ash to establish resistance while retaining genetic diversity.”
Recently, the first two genetic trials of ash were planted using seeds collected by ODF and others.
U.S. Forest Service geneticist Richard Sniezko said a genetic trial and finding resistant trees could take many decades.
“We don’t know if we will find resistance or if we do, how durable it will be. But by preserving the full range of genetic diversity in the species, if we do find resistance we can ensure trees that are cross-bred and reintroduced are well suited to all parts of their habitat range,” he said.
The emerald ash borer is native to Eastern Asia. It was discovered near Detroit, Michigan in 2002 and as it made its way farther west.
The emerald ash borer is about a half-inch long and an eighth of an inch wide. It’s known for its metallic, shiny green color. Anyone who sees an emerald ash borer should make a report of it online at the Oregon Invasive Species Council Hotline.
In Oregon, the insect has spread beyond the site it was originally discovered to nearby natural areas.
The Oregon Department of Agriculture issued a temporary emerald ash borer quarantine in Washington County in December to help prevent the spread of the invasive insect. The temporary quarantine began on December 20 and will be in effect until May 16. The quarantine prohibits tree materials from all ash, olive and white fringe trees from being moved to places outside Washington County.
“The strategy in Oregon is to slow the spread to give communities time to deal with the threat,” Williams said. “That way, communities will have more time to inventory their urban forest and identify all their ash trees, then make decisions about which ones to treat or remove pre-emptively. It also gives the time to make arrangements for what to do with all the ash wood that will become available as trees die.”
In 2017, it was estimated the cost to replace public ash trees in Portland alone would cost an estimated $49 million.