Dutch elm disease

A fungal disease affecting elm trees

 This article is about the disease affecting elm trees.
   For other uses, see Dutch elm disease (disambiguation).

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, North America, and parts of Asia.

History

The disease was first identified in the Netherlands in 1921, hence the name "Dutch" elm disease. It was later found to be caused by the fungus Ophiostoma ulmi. A more virulent strain, Ophiostoma novo-ulmi, emerged in the mid-20th century, leading to widespread destruction of elm trees.

Pathogen

The primary pathogens responsible for Dutch elm disease are Ophiostoma ulmi and Ophiostoma novo-ulmi. These fungi invade the vascular system of the tree, blocking the flow of water and nutrients, which leads to wilting and death.

Transmission

File:Elm bark beetle.jpg

The elm bark beetle is a primary vector for Dutch elm disease.

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 as they emerge, they carry the spores to new hosts.

Symptoms

Symptoms of Dutch elm disease include:

• Wilting and yellowing of leaves, often starting at the top of the tree.
• Defoliation and branch dieback.
• Brown streaking in the xylem when the bark is peeled back.

Management

Management of Dutch elm disease involves a combination of strategies:

• Sanitation: Removing and destroying infected trees to prevent the spread of the disease.
• Chemical control: Injecting fungicides into healthy trees to protect them from infection.
• Breeding resistant varieties: Developing and planting elm varieties that are resistant to the disease.

Impact

Dutch elm disease has had a significant impact on urban and rural landscapes, leading to the loss of millions of elm trees. This has affected biodiversity, ecosystems, and the aesthetic value of affected areas.

Prevention

Preventive measures include monitoring elm populations for signs of the disease, controlling elm bark beetle populations, and planting resistant varieties of elms.

Related pages

• Elm
• Fungal disease
• Ophiostoma
• Elm bark beetle