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Introduced in 1922 by a wholesale tree grower in Princeton, NJ, the Princeton American Elm is the only cultivated variety of American Elm (Ulmus Americana) that has an over 75-year landscape proven tolerance to Dutch
Elm Disease. In fact, its longevity surpasses that of all other selected cultivars by several decades.
Two streets in Princeton, NJ, lined with Princeton Elms in 1932, have a survival rate of 95% from ALL
causes, and show no sign of Dutch elm disease today, 70 years later. Despite the dense urban setting of these plantings, these trees are vigorously healthy, and have uniformly assumed the size, shape and proportions
of the classic American elm. Here are just a few observations and comments from experts in the field about the strength, vitality and resistant qualities of this remarkable variety.
In research testing at
the U.S. National Arboretum conducted by Dr. A.M. Townsend, a research geneticist for the USDA, groups of 12 clonal varieties as well as American elm seedlings were subjected to an artificially severe inoculation of
the most aggressive strain of Dutch elm disease. In the follow-up data to that research published in the June, 2001 issue of the "Journal of Environmental Horticultural," the Princeton American Elm scored
at the very top with a survival rate of 96%! A new National Arboretum introduction, Valley Forge, tied at the top with a 96% survival rate and another new Arboretum introduction, New Harmony, scored an 86% survival
rate. Of these three varieties, only one was originally selected for strong ornamental and horticultural reasons: THE PRINCETON AMERICAN ELM! Valley Forge and New Harmony were selected solely for DED resistance and
have not yet stood the test of time as ornamental shade trees. Another variety called the Liberty elm (which is actually 6 different varieties that are mixed when shipped) scored an 18% survival rate from the DED
inoculations.
Mr. William F. Monroe of Cincinnati, OH, who has spearheaded the replanting of American elms in that area, chose the Princeton American elm after it was evaluated by the Cincinnati Park Board's
Natural Resource Management Section and found to be a superior selection. Dr. T.Davis Sydnor, PHD, professor of Urban Forestry at Ohio State University, and who also participated in the Cincinnati elm selection
process, concurs by stating "of the disease resistant cultivars, 'Princeton' is generally considered to have the best form and growth rate."
In a cover article from the July 1996 issue of
"Agriculture Research" (published by USDA-ARS), staff writer Henry Becker writes: "American Elms are prized for their shade-providing vase shape and other aesthetic attributes. But their superior
adaptability, inherent vigor, hardiness and tolerance to stresses, especially in urban settings, are unsurpassed by most tree species."
Dr. Michael A. Dirr of the University of Georgia, author of
"Manual of Woody Landscape Plants," one of the most widely used reference books in horticulture, writes that the "hard disease resistant data and longevity of the Princeton American elm make it
worthy of use".
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