Dutch Elm Disease

Dutch Elm Disease (DED) is a fatal disease caused by a vascular wilt fungus, Ophiostoma novo-ulmi. The disease was initially introduced to the United States in the 1930’s, killing millions of elm trees, and to this day remains the most devastating shade tree disease in North America.

Dutch Elm Disease (DED) can be transmitted by way of a root graph between trees 50’ or less, but is most commonly vectored from a diseased tree to a healthy one by either the European Elm Bark Beetle or the native Elm Bark Beetle.  2-3 generations of Elm Bark Beetles reproduce every year, spreading the fungal spores to healthy trees by feeding on 2-4 year old branches. It takes 4-6 weeks after initial infection to show symptoms of Dutch Elms Disease (DED). Upon infection the fungus blocks the vascular system preventing water and minerals from reaching branches and leaves.

To determine Dutch Elm Disease (DED) progression, branches will dye followed by major limbs, and then ultimately tree death. In rare circumstances, Dutch Elm Disease (DED) resistance is found in younger elm trees, allowing a lifespan of 15-20 years; this also can be seen in older specimens, nevertheless, one can only expect the tree to live 1-2 years after initial infection.

Noticeable Signs 

Common signs of Dutch Elm Disease tend to show:

  • intermittent wilting of leaves on branches throughout the upper canopy, not to be confused with mechanical symptoms due to drought that can also cause a flagging effect throughout the entire canopy.
  • if the transmittal is from a root graph, flagging may be on lower branches nearest root graph. This is followed by a change in leaf color from green to yellow to brown, then finally shriveling up and dying.
  • It is simply not enough to base a determination of Dutch Elm Disease (DED) on flagging or leaf color change; to be certain a certified arborist should perform a consultation and peel the bark back to expose discoloration of the vascular system. This is followed by a brown discoloration of the diseased specimen along the water conducting vessels (xylem) of the wood

Treatment/Management

Most Dutch Elm Disease (DED) infected trees can’t be saved; however, if caught early enough sanitizing infected areas of the tree through proper pruning along with a fungicide, cannot only save the tree, but also protect it from future infestation. We recommend a macro-infused fungicidal trunk injection on the diseased elm with a product called Arbortech 20-S which provides 99.5% protection from Dutch Elm Disease for three growing seasons.

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