September 2004
Ulmus americana or American Elm

The American Elm: Ulmus americana
A Success Story

At one time the American Elm was one of the most popular street trees in the USA. The trees grow fast with a large vase shape that shaded many streets. The tree was adaptable to many sites and climates growing to a height of 80 plus feet high and a spread of 40 to 60 feet. Unfortunately the Dutch elm disease traveled through these cities being carried by insect or root grafts. In the late 50’s and 60’s this nearly caused many cities to loss its urban forest. There are still wide spread examples of this tree where they have been planted in isolated locations. At one time this tree was thought to be a pest free tree and that is why it was planted in such large numbers.

Today, through research and selection we have American elms that are tolerant of the disease that killed its parents. One of the tolerant selections that is available to us Valley Forge American Elm. After many years of research and testing Valley Forge was introduced by the U.S. National Arboretum. The plant grows to a height of 70 feet with a spread of 60 feet. This native upright arching and vase shaped tree resembles those used in the past. The plant has yellow fall color and is tolerant of the Dutch elm disease. Valley Forge, a tree found in Ohio, was selected by Dr. Denny Townsend who has worked with elm research throughout his whole carrier.

There are also other species and many hybrid elms on the market that are worthy of use in the landscape. Most of these have several parents and bring different shapes, leaf sizes and colors or bark characteristics. Below are just a few of the many selections of elms available today. Regal Elm is a hybrid cross that is resistant to Dutch Elm Disease with a strong central leader and pyramidal to oval shape. This selection from the University of Wisconsin grows to a height of 50 plus feet with a spread of up to 30 feet. It is adaptable in many soil types in both street and lawn situations. Accolade Elm is a hybrid that resembles the shape of the native American elms. This tree was introduced by Morton Arboretum, in Lisle Illinois and is expected to grow to a height of 80 plus feet. Accolade has extremely glossy green leaves that are resistant to Dutch Elm Disease and elm leaf beetles.

Chinese Elm (Ulmus parvifolia) grows to a height of 40 feet and has an equal spread. The tree has finer textured foliage and develops an extremely attractive mottled bark as it matures. Frontier Elm is a hybrid with glossy green summer foliage and a dark red purple fall color that is quite unusual for elms. This plant has a mature height of 35 plus feet with an equal spread.

While we encourage the planting of elms be sure not to repeat planting mono cultures of trees in communities. A healthy urban forest has a mix of species placed in locations where they have enough space to grow to maturity.

It is exciting to realize that we can once again enjoy the majesty of American Elm as well as many other elms in our communities without fear of loss to Dutch Elm Disease.

Randy Zondag, OSU Extension Horticulture Agent, Lake County
Photos Courtesy Bill Hendricks, Klyn Nurseries, Inc., Perry OH