Oregon ash (Fraxinus latifolia): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.

At a glance

Item	What the source records
Scientific name	Fraxinus latifolia Benth. in USDA PLANTS, olive family
Other names	No other common names listed in Silvics; USDA PLANTS lists none
Native status, USDA PLANTS	Native in Canada and the lower 48 states
Size and age, Silvics	Moderately rapid growth for 60 to 100 years, reaching 18 to 24 m (60 to 80 ft) and 40 to 75 cm (16 to 30 in) in diameter in 100 to 150 years on good sites; individuals may grow twice as large and reach 200 to 250 years under favorable conditions; the largest known is 18 m (59 ft) tall and 668 cm (263 in) in circumference
Form, Silvics	Forest-grown trees have long, clean trunks and narrow, short crowns; open-grown trees on moist sites have short trunks and wide, round-topped crowns; on dry sites or at high elevations it is often a small, crooked tree under 8 m (25 ft)
Roots and shade, Silvics	A moderately shallow but very fibrous and wide-spreading root system, windfirm; classed as intermediate in tolerance of shade
Green weight of the wood, NRS-38	50 lb per cubic foot, without bark

Native range

The Silvics of North America handbook (Agriculture Handbook 654, volume 2, 1990) calls Oregon ash the only native species of Fraxinus in the Pacific Northwest, commonly found in riparian habitats and not managed for timber production. It is found from northern Washington to southern California. The handbook says some trees growing wild in southwestern British Columbia are thought to have come from seed spread from planted ornamentals, while USDA PLANTS records the species as native in Canada and the lower 48 states.

In Washington the handbook places it along the shores of Puget Sound, in the western Cascade Range and along the southwestern coast, but not in the Olympic Mountains, and along the Columbia River from the coast east to The Dalles, Oregon. In western Oregon it occurs from the coast into the western Cascades and is prominent in the valleys, particularly the Willamette Valley. In California it is found in the north Coast Ranges as far south as Santa Clara County, in the Sierra Nevada, in the delta region of the Great Valley, and in the canyons of the Pit and Sacramento Rivers. More than 2.5 million cubic m (90 million cubic feet) of growing stock occur in Oregon and Washington.

Uses

Silvics says the most notable use of Oregon ash is for fuel, because it splits easily and has high heat value. It says the symmetrical shape, rapid growth and hardiness have led to planting as an ornamental and street tree in cities within the native range, in the Eastern United States, in southwestern British Columbia and in Europe. Birds and squirrels eat the seeds, and deer and elk browse the trees. The handbook says that south of the Kern River in California the tree becomes similar to velvet ash, and anatomical features point to possible hybridization between the two.

Wood

The Wood Handbook (FPL-GTR-282, 2021) lists Oregon ash in the white ash group, which it describes on the green ash page. It says Oregon ash has somewhat lower strength properties than American white ash but is used for similar purposes on the West Coast. Silvics names tool handles, sports equipment, boxes, cooperage and furniture as uses within the native range. Table 5-3b has a separate Oregon ash row, shown below.

Wood Handbook Table 5-3b	Specific gravity	Modulus of rupture (lbf per square inch)	Side hardness (lbf)
Green	0.50	7,600	790
At 12% moisture content	0.55	12,700	1,160

The Wood Handbook states that specific gravity is based on oven-dry weight and the volume when green or at 12% moisture content. The green weight of the wood without bark is in the NRS-38 table, the same figure used in the log weight calculator.

Diseases, insects and damage the agencies name

Silvics (1990) says Oregon ash is attacked by a variety of insects.

Seed weevils. Thysanocnemis weevils can destroy 60 percent of a seed crop and are found throughout the range.
Foliage and twig insects. The Arizona ash lace bug, a plant bug, the snowy tree cricket and the fall webworm (see fall webworm) are listed as harmful to ornamentals but not considered forest pests. The Oregon ash bark beetle causes no economic damage but is often abundant in cordwood.
Fungi. Several leaf spot fungi, a powdery mildew and twig fungi are listed. The heart rot Perenniporia fraxinophilus attacks older trees and may cause extensive cull.
Mistletoe. The true mistletoe Phoradendron longispicum is found on Oregon ash; see mistletoe on trees.
Emerald ash borer. The Wood Handbook says Oregon ash grows along the Pacific Coast and is presently considered near threatened, while the three eastern white ash group species are considered critically endangered because of the emerald ash borer. The guide on emerald ash borer rules by country gives each agency's wording and the date on its page.

The guide on reporting a pest in the United States and the Canada reporting page give the offices that take sightings of regulated pests. Who may apply pesticides is in pesticide licences by country.