By Laura Pottorff, Colorado State University Cooperative Extension, Horticulture/Plant pathology
Dutch Elm Disease, which has devastated American Elm trees along the Front Range, probably came to the U. S. through elm logs imported from Europe. The disease, first identified in 1921 in Holland, is carried by bark beetles that were present in the imported logs. Female bark beetles tunnel into trees to lay eggs and introduce the DED fungus. The fungus plugs up the tree's vascular system, girdling the tree. The entire tree, or individual branches, wilt. Control methods include removal of diseased trees, control of elm bark beetles and, in some cases, injection of fungicide into the trees. As a result of DED's introduction into the U.S., the government now has strict quarantine laws to prevent further such problems.
Photo: National Park Service
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Date last revised: 01/05/2010