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 Summer/Fall
2000 |
Return of the Native The American Elm Finds Tolerance for a Dread Disease By John Wall  Around 1900, thoroughfares across the United States were graced by tall, beautiful American elms. These vase-shaped trees, characterized by weeping limbs, commonly grew more than 100 feet tall and thrived in urban environments. They stood up to air pollution, road salt, car crashes, poor soil, and almost all other urban maladies. All that changed in 1930, when a French freighter off-loaded elm logs destined for several Ohio furniture factories. Hidden within these logs were elm bark beetles—insects that use dead or dying elms as breeding sites. The insects carried with them the fungus that causes Dutch elm disease. After the French elm logs were loaded onto a train in New York City, the beetles abandoned the logs to feed on live elms along the train route to Columbus and Cleveland. U.S. Department of Agriculture scientists were later able to reconstruct how the disease spread along the train tracks, into nearby cities, and eventually across the country. By 1970, some 77 million American elms were dead, and tree-lined streets that had been gloriously shaded were as barren as a battlefield. |
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Penn State | College of Agricultural Sciences | ICT Copyright - Alternative
Media - Affirmative
Action |