What is Dutch Elm Disease and why is it so deadly?

Since arriving in the United States in 1930, Dutch Elm Disease (DED) has been one of the most devastating urban forest diseases in history, killing nearly 77 million trees by 1970.

DED continues to kill mature Elm Trees today – so what is this disease and why is it so destructive?

  • DED is a fungal disease facilitated by European and American elm bark beetles as they carry the spores with them from tree to tree.

  • Young beetles introduce the disease as they feed on twig crotches, leaving behind spores as they chew.

  • The fungus spreads throughout and clogs up the elm tree’s vascular system, causing leaves to wilt and eventually killing the tree.

  • DED can also spread through natural root grafts ­­– when the roots of an infected tree join with those of a healthy elm.

Symptoms and Management

  • The first sign of Dutch Elm Disease is known as flagging: isolated areas of yellow leaves in a tree’s crown. The isolation of yellow is what makes this symptom unique to DED. Other diseases cause yellow leaves in the crown but will typically affect the entire crown.

  • DED will also cause discoloration under the outer bark of infected branches – typically consisting of brown or black streaks.

  • Early detection is the best way to manage Dutch Elm Disease. If flagging is identified early enough, a certified arborist can remove infected limbs and potentially save the tree.

  • Professional arborists can destroy natural root grafts and stop the spread of DED.

  • Destruction of dead of dying Elm trees is also pivotal to stop the spread of DED, as it prevents more beetles from using them.

It takes decades to replace a mature tree. To keep your elms and other trees healthy, or for more information on preventative measures Ripley can take against DED, please contact Ripley Tree Service, an independent family business serving Northeast Ohio since 2001.


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