Dutch Elm Disease An ounce of prevention

By: Jeffrey P. Hagfors, Certified Arborist

Winter 2003 Newsletter in Adobe PDF format Dutch Elm Disease (DED) is a fungus that attacks the vascular system of elm trees. The disruption occurs as the rapidly colonizing fungus quickly outpaces the tree’s natural defenses and the tissue becomes plugged up. The leaves wilt because they no longer get any water from the roots and the tree dies.

Dutch elm disease is spread by the feeding of elm bark beetles, and through root grafting. The elm bark beetles carry the disease as they do their feeding in the young branches of healthy elms. Elm bark beetle activity starts in late May and continues through August.

Dutch elm disease can also be spread below ground through the roots. Infection of DED through root grafting takes place when the roots of an infected elm are in contact with the roots of a healthy elm.

The first symptom of DED is called flagging. Flagging can be subtle at first with leaves turning a pale green or yellow. As the wilting leaves turn brown and begin to fall, the disease becomes much more noticeable. Flagging can begin as early as 4 weeks after infection. In most cases (not all) once an elm is infected it cannot be saved. In most cases uninfected elms can be protected.

Elm trees can be protected from DED infection caused by the elm bark beetle. A properly dosed macro infusion of Arbotect fungicide can protect non-infected elms for up to three growing seasons. This practice is over 99% effective. Timely renewal every 3 years is needed to extend the protection. We guarantee our Dutch elm disease prevention.

Elm trees that become infected through root grafting cannot be saved. Macro infusion of Arbotect fungicide does not protect elms from Dutch elm disease through root grafting. If elms are at risk of root grafting with other elms that are either unprotected or infected with DED other steps need to be taken to insure their protection. Mechanically or chemically severing roots to a depth below the root line might need to be done to isolate the tree and remove the risk of root grafting.

Call your Wachtel Certified Arborist for an inspection and evaluation to find out what preventative steps are needed to preserve your elms.

© Copyright 2003 – Wachtel Tree Science & Service, Inc.

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