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A Brief History of the "Princeton" American Elm
Once the dominant feature in the American landscape east of the Rockies, the American elm ruled supreme as the shade tree of choice for generations of Americans prior to World War II. These large, graceful specimens
with their upright, vase-shaped habit have shaded so many American streets that "Elm Street" is generally believed to be the most common street name in the United States. Unfortunately, in the early 1930s,
a fungal infection borne in beetles was introduced into the United States in a shipment of lumber from Europe. This fungus turned into a deadly and catastrophic blight wiping out tens of millions of American elm
trees over a period of decades. It was later labeled Dutch elm disease and is still referred to in that manner.
Selecting a classic elm.
The Princeton American elm was selected by a wholesale tree
grower in New Jersey from a single specimen around 1920 because of its strong horticultural traits. These strong characteristics included its classic elm vase shape, large leathery foliage and observed resistance to
known elm maladies of that time. The selection of this elm was made a decade before the introduction of Dutch elm disease into the United States.
By grafting his cuttings onto American elm root stock, the
grower produced specimens that were uniform in appearance and shared other worthwhile characteristics. This was invaluable, since many of these trees were to be planted in multiple quantities to line streets and
boulevards. Unlike trees planted from seed, which can vary greatly in shape and size, similar to human beings, these elms would show little variation in appearance and growth rate.
The tree was named
Princeton American elm and was first sold around 1922. Many of these elms were sold including those that were used to line two notable Princeton, NJ streets in 1932. However, the outbreak of Dutch elm disease (DED),
soon stopped virtually all production and planting of American Elms.
Dark times.
Many decades passed, but no replacement for the American elm was found. No other tree seemed to combine the
beauty, grace and remarkable adaptability to so many environmental conditions. No other tree also possessed its vast geographic and climatic range. At the same time, chemical treatment and horticultural practice
programs to save surviving elms proved to be no more than costly short-term solutions. As a result, concerted efforts were begun and continued by various government, academic, horticultural and private groups to
find either a suitable substitute for the American elm or an actual American elm that was immune or at least resistant to DED.
Discovering a disease-tolerant variety.
The research for a disease
resistant American elm, or more correctly disease tolerant , since no American elms have proven to be completely immune to DED, provided some interesting results. In testing performed at the USDA National Arboretum,
many varieties and chance seedlings of American elm were artificially inoculated with severe doses of DED. A few of these varieties showed varying degrees of tolerance to the fungus, which is the ability of the tree
to host the fungus without succumbing to it. Notably, among the most tolerant was the Princeton American elm. It was the only cultivated variety of American elm with a landscape proven track record of three quarters
of a century, including streets planted in 1932. Those street plantings survive today with over a 95% survival rate from ALL causes.
Reintroducing a classic.
The Princeton American elm has recently reemerged in the professional landscape trade. It has been used in several high-profile projects, including several blocks of street
plantings in downtown Cincinnati. By using modern, improved vegetative propagation, versus grafting, Riveredge Farms is now able to produce a tree that is a Princeton American elm from top to bottom that can be
easily planted and cared for by virtually anyone. This tree is not a hybrid but a true American elm (Ulmus Americana) with a proven scientific record of Dutch elm disease resistance and longevity on the street.
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