What is Dutch Elm Disease?

Dutch Elm Disease (DED) is a destructive fungal disease that affects elm trees. Despite its name, the disease did not originate in the Netherlands, but was first studied and identified by Dutch scientists in the 1920s. To learn more about the disease's origins, see Where Did Dutch Elm Disease Come From?

The Disease

Dutch Elm Disease is caused by fungi in the genus Ophiostoma, primarily Ophiostoma ulmi and Ophiostoma novo-ulmi. These sac fungi are spread by elm bark beetles and through root grafts between nearby elm trees. For detailed information about disease transmission, see What Causes Dutch Elm Disease?

How It Spreads

The disease spreads in two main ways:

Beetle Transmission: Elm bark beetles (Scolytus and Hylurgopinus species) carry fungal spores from infected trees to healthy trees as they feed and breed.

Root Grafts: The fungus can spread through natural root connections between closely planted elm trees.

To understand how the disease progresses within an individual tree, see How Does Dutch Elm Disease Spread in a Tree?

Impact

Dutch Elm Disease has had a catastrophic impact on elm populations:

Killed millions of elm trees across North America and Europe

Devastated urban landscapes where elms were commonly planted as street trees

Led to the near-extinction of American elm as a landscape tree

Continues to threaten remaining elm populations worldwide

For information about the geographic extent of the disease, see What Is The Range of Dutch Elm Disease?. Despite this impact, elms are not headed for extinction.

Timeline

1920s: First identified in the Netherlands

1930s: Arrived in North America

1960s-1970s: Peak devastation period

Present: Ongoing management and research efforts continue

Related Information:

Learn to identify the disease: What Are the Symptoms of Dutch Elm Disease?

Understand treatment options: Can Dutch Elm Disease Be Treated?

Explore resistant varieties: Are There Trees Resistant To Dutch Elm Disease?

Safety concerns: Is Dutch Elm Disease Harmful to Humans?