Fraxinus pennsylvanica 'Summit'
Common Name: green ash
Type: Tree
Family: Oleaceae
Zone: 4 to 9
Height: 50.00 to 70.00 feet
Spread: 40.00 to 60.00 feet
Bloom Time: April to May
Bloom Description: Greenish-purple
Sun: Full sun
Water: Medium
Maintenance: Medium
Suggested Use: Shade Tree, Street Tree
Flower: Insignificant
Leaf: Good Fall
Tolerate: Deer, Air Pollution

Culture

Easily grown in average, medium moisture, well-drained soils in full sun. Prefers consistently moist, humusy loams, but established trees demonstrate adaptability to a wide range of soils and growing conditions.

Noteworthy Characteristics

Fraxinus pennsylvanica, commonly called green ash, has the largest growing range of any of the native ashes, extending from Nova Scotia to Alberta south to Florida and Texas. This is a lowland species that is commonly found throughout the State of Missouri in low woods, floodplains and along streams, ponds and sloughs (Steyermark). It is a medium sized tree, typically growing 50-70’ tall. Young trees are pyramidal in shape, gradually maturing to a more rounded but usually irregular crown. Green ash is similar in appearance to white ash (see Fraxinus americana), except, inter alia, (a) flowers appear after the foliage emerges, (b) leaflet undersides are green, (c) leaflets are toothed from midleaf to tip and (d) leaflet stalks are winged. Green ash is primarily dioecious (separate male and female trees). Clusters of apetulous purplish male and female flowers appear on separate trees in April-May after the foliage emerges. Fertilized female flowers give way to drooping clusters of winged samaras (to 2” long) that ripen in fall and may persist on the tree throughout winter. Features odd-pinnate compound leaves, each with 5-9 leaflets. Oval to oblong-lanceolate leaflets (3-4” long) are medium green above and below. Foliage turns yellow in fall, with the quality of the fall color often varying considerably from year to year. Gray-brown bark develops distinctive diamond-shaped ridging on mature trees. As with white ash, the wood of green ash is commercially used for a variety of products including tool handles, oars, garden furniture and sports equipment.

'Summit' is a male cultivar that was first introduced into commerce in 1957 by Summit Nursery in Stillwater, Minnesota. It is a vigorous, pyramidal tree that produces a strong central leader. Clusters of inconspicuous, apetulous, greenish-purple male flowers appear in April-May after the foliage emerges. Compound, odd-pinnate, medium green leaves (to 12" long), each with 5-9 serrate, oval to oblong-lanceolate leaflets (3-4" long), are attractive throughout the growing season. Foliage turns yellow in fall, with the quality of the fall color often varying considerably from year to year. Ash-gray to gray-brown bark develops distinctive diamond-shaped ridging on mature trees.

Problems

The emerald ash borer is native to Asia. It was first discovered in the U. S. (southeastern Michigan) in 2002. It has now spread to a number of additional states in the northeast and upper Midwest, and is expected to continue spreading. Emerald ash borer will typically kill a green ash tree within 3-5 years after infestation. Once infestation occurs, it is very difficult to eradicate this pest which feeds under the bark and bores into the wood. 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 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 may be damaged by high winds and accumulations of snow/ice.

Garden Uses

Planting new green ash trees is no longer recommended given the susceptibility of this tree to the emerald ash borer. Green ash trees have typically been used over time as street, shade or lawn trees.