Hardy Asian Elm Tree Shows Promise in US
Tree expert aims to popularize robust species from China
LISLE, ILL. — AS a child in Oklahoma in the 1930s, George Ware loved strolling through the shade of the lofty, verdant arcades of American elm trees that lined the streets of Midwestern towns.
Today - after decades of blight have destroyed an estimated 50 million elms or roughly 60 percent of the trees in towns and cities across the United States - Dr. Ware has made a promising discovery for reviving the graceful, vase-like shade trees of his youth.
A leading US expert on elms at the Morton Arboretum in Lisle, Ill., Ware has identified a species of elm that greatly resembles the American elm but is highly resistant to the blight, Dutch elm disease. Beginning next spring, Ware will seek to popularize the elm trees by distributing thousands of seedlings nationwide at no cost.
``The idea is to get elms back on the street and add diversity to protect us from [the ecological costs of] monoculture,'' the overcultivation of one type of tree, he says.
The fruit of Ware's lifelong affinity for the elm is a handsome, sturdy tree known as the David elm or Ulmus davidiana. It is named after Father Armand Davis, a French missionary who documented the tree in China in the late 19th century.
In 1980, as he searched for hardy elms for the Midwest, Ware obtained seeds for the David elm and a dozen other Asian elm species from a botanical garden in the city of Harbin in northeastern China or Manchuria.
Ware led this country's first and only research on the dozen Asian elms as part of the arboretum's ``elm-improvement program.'' His experiments confirmed that all the Asian elms are highly resistant to Dutch elm disease.
Meanwhile, as the David elm matured, Ware was delighted to watch it replicate the soaring, fluted appearance of the American elm. Under good conditions the David elm can grow to 50 feet, which is about the height of American elms in the Midwest.
In 1984, Ware gleaned new, hopeful insights about the David elm from a Chinese-language monograph published in Harbin. The monograph indicated that the David elm thrives in the harsh Manchurian climate.
Moreover, it suggested that unlike other species, the David elm grows best in areas of open landscape and poor soils, such as abandoned fields, lake shores, and areas along railroad tracks.
To confirm his impressions of the David elm, Ware in 1990 led an exploratory trip to a nature preserve in northern Manchuria near the Chinese-Russian border. There, he was elated to find the trees just as he had envisioned them, flourishing in rugged, open terrain.
``It was exactly what I was looking for,'' Ware says. ``I was euphoric.''
The David elm's tolerance for bitter winters, open spaces, and barren soils made it a perfect candidate to thrive in Chicago and other cities and towns across the American Midwest, Ware says.
``The David elm is a pioneer of a kind - a good, dependable tree for tough places,'' he says as he stands beside a 12-year-old David elm growing in the arboretum's elm collection.
In Chicago, for example, Ware says the David elm can grow well along streets and railway lines. It can weather the city's fierce winter storms, poor spring drainage, and soil that is littered with rubble from the Great Chicago Fire of 1871.
``The David elm has been subjected to these kind of adverse conditions for millennia,'' Ware says.
Ware has not found a single David elm that is susceptible to Dutch elm disease, despite repeated exposures at the arboretum.
Dutch elm disease was first confirmed in the United States in Cleveland, Ohio, in 1930, apparently after beetles carrying the fungus arrived in the country on logs imported from Europe. The blight spread across the entire US range of the American elm between 1930 and 1970. It continues to destroy an estimated 400,000 trees each year.
Today, the Morton Arboretum has about 100 young David elms in its experimental grounds. In addition, some 4,000 David elm seedlings are growing in flats in its large, sunlit greenhouse. Next spring, when the seedlings reach heights of two to three feet, Ware will distribute them to nurseries as well as to amateur arborists across the US.
Although Ware prizes the elm, he rules out a return to the days when the shade tree dominated much of the American landscape.
``We are interested in the elm for diversity,'' says Ware. ``We have oak, ash, maple, and linden, but very few elms.''