Dutch Elm Disease

Dutch elm disease is caused by two similar fungus species: Ophiostoma ulmi & Ophiostoma novo-ulmi. The fungus is carried and spread from three species of Elm bark beetle, which feeds and overwinters beneath the bark of the tree. The beetles are attracted to Elm trees that have been recently pruned, are sick, weak or dying. Adult beetles emerge from infected trees and will relocate to healthy trees to feed and lay eggs, therefore infecting the healthy trees with the fungus and furthering the spread of the disease.

Dutch elm disease affects the trees ability to conduct water. Symptoms of Dutch elm include: portions of the canopy yellowing or foliage wilting, dead leaves curl and remain on branches, peeled back bark reveals brown to blackish streaks in the wood. DED is usually a fatal disease for these trees.

Scientific Name: Ophiostoma ulmi & Ophiostoma novo-ulmi

Common Name: Dutch Elm Disease

Family: Ophiostomataceae

Type: Fungi

Control Methods

Most control methods are preventative as little can be done to remove the fungus from the tree once it has moved through the vascular system.

Pruning out affected branches and limbs can slow and sometimes stop the spread of the fungus. Limbs that show symptoms of DED should be removed the same year the infections starts. If the canopy has several affected limbs, the tree should be taken down.

Dutch Elm disease resistant cultivars or varieties are a suitable choice for new plantings or as a replacement option.

Some evidence has shown fungicide injections to be effective at preventing initial infections. Treatment usually needs to be repeated every 1-3 years.

Disposal

Infected wood should be buried, debarked, or chipped to prevent spreading the disease. Do not combine DED elm wood with food scraps or other collected waste. DED wood can be burned immediately, but do not stack, pile or save for future use. Phone your local transfer station or green waste facility before transporting to ensure it can be safely disposed of.