Oregon Ash

Fraxinus latifolia, Oregon ash, is the only ash native to the Pacific coast, found along streambanks, floodplains, and seasonally wet meadows from southern Washington through Oregon into central California. It is a key riparian tree of Pacific lowland forests, stabilizing streambanks and providing shade that keeps salmon-bearing waters cool, and its wood has traditionally been used by Pacific Northwest Indigenous peoples for tool handles and canoe paddles.

For years, Oregon ash was one of the only North American ash species to have escaped emerald ash borer (Agrilus planipennis) entirely, since the beetle's spread had remained confined to the eastern two-thirds of the country. That changed in June 2022, when EAB was confirmed in Forest Grove, Oregon — its first detection anywhere on the West Coast — and it has continued to spread through the Willamette Valley since. Oregon ash is now considered highly vulnerable given how little time West Coast populations, land managers, and nurseries have had to prepare compared with the eastern species that have been fighting the borer for two decades. Anyone in or near the current Pacific Northwest infestation zone should treat new ash plantings with the same caution as anywhere else EAB is established, and watch existing streamside trees closely.