Letter to The Editor

Dear Dr. Miller:

I read with interest in the Journal of Arboriculture (September 2001) the article titled “Comparative Tests of Six DED-Tolerant Elms: A Preliminary Report on Nursery Performance.” The information was quite interesting. However, there was one major area of omission, which is the principal value of this research even beyond resistance to Dutch elm disease. That is the appearance of the structure of the elm tree 25 to 50 years after its planting. It is obviously difficult to determine some of this future growth. However, a genetic understanding of the parent species or hybrids that the cultivar is obtained from may give an indication of its future value as a shade tree.

Many of us remember the Chinese chestnut (Castanea mollissima) being a replacement for the American chestnut (C. dentata) and how unattractive and vulnerable to storm damage the Chinese chestnut was. Likewise, the Chinese elm (Ulmus parvifolia) did not have anywhere near the character or shape of the American elm (U. americana).

Other replacement species that have been introduced, most principally as replacements for American elm, have not developed into a character and shape that would be suggestive of those values appreciated in the American elm. An excellent example is Zelkova serrata, a low, squatty tree that is most unattractive when compared to the graceful and majestic habit of the American elm.

It is hoped that in some future article that time and attention can be given to these important characteristics to determine whether it is worth developing a particular new elm that is resistant to Dutch elm disease on the basis that it has a high branching pattern that trucks can pass underneath, good crotch development to help resist storm damage, and the ability to withstand the many stresses of city life. These features have proved to be valuable assets of the American elm.

• © 2002, International Society of Arboriculture. All rights reserved.