White Ash

White Ash (Fraxinus americana)

Full sun, medium moisture, prefers fertile deep soils but grows in a variety of soils from loam to clay loam to sandy as long as not too rocky or dry; slightly acid to neutral pH 6.0–7.5.

60–90 feet tall by 25–60 feet wide; dioecious with tiny green to purple flowers in April; female trees produce dense clusters of winged samara seeds 3–5 cm long. Growth rate medium. Rounded, dense crown. Fall color red, purple, or yellow.

Native region: Statewide in Tennessee on moist, well-drained slopes, bottomlands, and floodplain margins.

Planting of F. americana is no longer recommended anywhere in the eastern United States. Emerald ash borer (Agrilus planipennis), a metallic green beetle introduced from Asia, has moved through Tennessee in force and kills infected trees within 3–5 years by girdling the cambium beneath serpentine larval galleries. Any existing white ash in a Middle Tennessee landscape should be assessed for infestation — S-shaped galleries under bark, D-shaped exit holes 3–4 mm wide, and crown dieback from the top down are definitive signs. Systemic trunk injection with emamectin benzoate can protect high-value specimens for 2–3 years but requires professional application. Ash yellows, caused by a phytoplasma, compounds decline in already-stressed trees. Do not plant replacement ashes of any species (F. pennsylvanica, F. velutina) — all native ash species are susceptible to emerald ash borer.