Ash Trees – the November 2015 Tree of the Month

by Ann Farnham

Ash trees are ubiquitous in our town because they can grow almost anywhere; they may have been over-planted because of this robustness. They populate our yards, streets, golf courses, parks and woodlands. Exceptional as shade trees, they tolerate all kinds of conditions, and have beautiful fall foliage. These medium–to-fast growing trees range from Nova Scotia and Manitoba in the north and to North Florida and Texas in the south.

There are many species of Ash; our most common are White Ash (Fraxinus americana), and Green Ash (Fraxinus pennsylvanica). These two species are challenging to differentiate but suffer the same problems shared with all the Ashes: many fungal diseases and insect predation. Importantly, the recently introduced Emerald Ash Borer is emerging as the most serious pest afflicting Ash trees today. The White Ash in its native habitat is primarily a forest tree while Green Ash is mainly a riparian species.

Both species have compound leaves (usually 5 to 7 leaflets per leaf) which measure 8-15” long, arranged opposite each other on a stem. They are dark green in summer and the fall foliage ranges from bright yellow to maroon and deep purple. The bark is grey to grey-brown and mature trees have a furrowed, narrowly ridged diamond shaped texture. The flowers, which appear before the leaves in spring, are inconspicuous. The fruit, known as samaras, are profuse, flat, and measure 1” to 2” long.

Ash wood is dense and white. It is used for baseball bats, furniture, tool handles, and flooring, among other things which require strength and resilience.

This fine and useful tree, however, seems doomed. The invasive Emerald Ash Borer (EAB) is killing ash trees throughout the North America in huge numbers. Many municipalities are taking down trees preventatively and at this time many thousands of these trees have been preemptively cut down or died from the EAB, which seems impossible to eliminate. The EAB was first introduced in Michigan from Asia in 2002 and has now migrated to the east coast. It has been spreading in Pennsylvania for the last few years and last year was found in New Jersey.

A recent survey, conducted by Rutgers’ Urban Forestry Program found more than 840 Ash trees growing on Ewing public land within 10’ from sidewalks and trails alone. It is predicted that the Ash tree loss in Ewing will be enormous.

For more information and details about the Emerald Ash Borer, please check out our informational page on this website.