Dutch elm disease

A fungal disease affecting elm trees

Dutch elm disease (DED) is a fungal disease that affects elm trees, caused by the ascomycete fungi in the genus Ophiostoma. The disease is spread by the elm bark beetle and has devastated elm populations across Europe and North America.

History

The disease was first identified in the Netherlands in 1921, hence the name "Dutch elm disease." It spread rapidly across Europe and later to North America, causing widespread destruction of elm trees.

Pathogen

The primary pathogens responsible for Dutch elm disease are Ophiostoma ulmi and Ophiostoma novo-ulmi. These fungi infect the xylem of the tree, disrupting water transport and leading to wilting and death.

Transmission

Fungal infection on an elm tree

The disease is primarily spread by the elm bark beetle, which carries the fungal spores from infected trees to healthy ones. The beetles breed in the bark of dead or dying elms, and the larvae create galleries under the bark, which can be seen in infected trees.

Beetle galleries under the bark of a Wych elm

Symptoms

Infected trees exhibit wilting and yellowing of leaves, often starting at the top of the tree and progressing downward. The leaves may curl and turn brown, and the tree may die within a few weeks to a few years, depending on the severity of the infection.

Impact

Dutch elm disease affecting a mature English elm

The impact of Dutch elm disease has been devastating, leading to the loss of millions of elm trees. This has significantly altered landscapes and ecosystems, as elms were once a dominant tree species in many areas.

Control and Management

Efforts to control Dutch elm disease include the removal of infected trees, the use of fungicides, and the breeding of resistant elm varieties. Quarantine measures and public awareness campaigns have also been implemented to prevent the spread of the disease.

Control notice for Dutch elm disease

Cultural Significance

Elms have been historically significant in many cultural landscapes

Elms have been an important part of cultural landscapes, often planted in parks and along streets. The loss of elms due to Dutch elm disease has had a significant cultural and aesthetic impact.

Current Status

While efforts to control the disease continue, Dutch elm disease remains a significant threat to elm populations worldwide. Research into resistant varieties and improved management practices is ongoing.

A diseased elm in Edinburgh

Related pages

• Elm
• Fungal disease
• Elm bark beetle
• Ophiostoma

A mature elm tree