Dutch elm disease (DED) is caused by a fungus and is highly lethal to American and European elms. The fungus spreads through root grafts, elm bark beetles, and human activity such as moving and storing elm wood. The main visual symptom of DED, known as “flagging,” is a sudden wilting or drooping of leaves in the tree, often on a single branch or limb. Flagging leaves quickly turn from grey-green to brown as the fungus invades the vascular tissue of the tree, blocking the tree’s water supply. Because fresh pruning wounds attract the elm bark beetle, elm pruning is restricted to times of beetle inactivity. Also, the state of Oregon has declared an emergency quarantine of all elm wood; elm wood must be chipped or de-barked and buried and cannot be stored for firewood. View the Elm Protection Program to learn more about the disease and Urban Forestry’s strategy for conserving Portland’s elm canopy.
American elms, Dutch elms, English elms, Wych elms, Camperdown elms, smoothleaf elms
Fungicide can be injected into elm trees as a preventative treatment. A certified arborist must supervise the fungicide injection procedure. Save Our Elms and affiliates, local nonprofit organizations, bring communities together to fundraise, inoculate elm trees, and replant trees that have been removed due to Dutch elm disease.