Water Ash Fraxinus pennsylvanica

Green Ash is a deciduous tree that may grows to 65 feet and occasionally to 120 feet tall with a trunk 2 to 3/1/2 feet across. Young trees, which have soft silky hairs covering twigs, the undersides of leaves and leaf stalks, are commonly known as Red Ash. Mature trees with smooth leaves and branches are known as Green Ash.

The leaves are opposite and pinnately compound with 7 to 9 leaflets. The bark is gray-brown with shallow furrows and crisscrossing ridges which form x-patterns. Small, light green to purple flowers, with no petals, mature in loose panicles in early spring. The female tree produces a single-winged, dry, flattened samara with a slender, thin seed cavity that matures in the fall. These can be numerous and can make a mess when they fall to the ground. Male trees are usually preferred in the home landscape because they do not produce fruit.

This plant is the most widely distributed of all the ash tree species, transplants well and grows in a variety of locations and soils. They are also very adaptable as they tolerate drought, wind, moderate salt, and alkaline soil. It is often found in bottom lands and swamps, especially along brown water rivers and low ground of the Piedmont and lower North Carolina mountains, but rarely on mesic upland disturbed sites

Insects, Diseases, and Other Pest Problems:  Planting new green ash trees is no longer recommended given the susceptibility of this tree to the emerald ash borer. The Emerald ash borer will typically kill an ash tree within 3 to 5 years after infestation. Once infestation occurs, it is very difficult to eradicate this pest which feeds under the bark and bores into wood. Emerald ash borer is native to Asia and was first discovered in the U.S. in 2002. It has now spread to a number of additional states in the northeast and upper Midwest, and is expected to continue spreading. This borer now constitutes a serious threat to all species of ash in North America. Green ash trees are generally susceptible to a number of additional insect problems including ash borer, lilac borer, carpenter worm, oyster shell scale, leaf miners, fall web worms, ash sawflies, and ash leaf curl aphid. Potential disease problems include fungal leaf spots, powdery mildew, rust, anthracnose, cankers, and ash yellows. General ash decline is also a concern. Brittle branches are susceptible to damage from high winds and snow/ice.

VIDEO created by Ryan Contreras for “Landscape Plant Materials I:  Deciduous Hardwoods and Conifers or Landscape Plant Materials II:  Spring Flowering Trees and Shrubs” a plant identification course offered by the Department of Horticulture at Oregon State University