Dutch Elm Disease

Characteristics

Dutch elm disease is a highly infectious, fungal disease. The disease is spread by elm bark beetles or through root grafts from infected elms trees.

When spring begins, the bark beetles emerge and attach to healthy trees. During this process the beetles spread fungal spores attached to their body. The fungus grows in the sap-conducting tissues under the bark causing wilting and browning of tree foliage. Infections are often fatal, and infected elm trees can die as soon as one month after infection.

Signs & Symptoms

Infected trees will have sections of canopy that will suddenly turn yellow (flagging), usually around mid-June. After yellowing, the leaves will turn brown and curl. If the tree survives until the following year, leaves will emerge small and die shortly afterwards. Usually by the time external symptoms are visible, the entire tree will be infected with the fungus.

Dutch elm disease will capitalize on trees amid dry weather. During droughts, infected trees will often show signs and symptoms of infection very fast.

Treatment & Recommendations

Monitor trees for symptoms of infection throughout the summer. Prune and remove all dead branches and trees from the site. High valued elm trees should be injected with a registered fungicide.

When treating elm trees, it is important to be proactive as opposed to reactive. If a tree is showing signs and symptoms of Dutch elm disease it can be too late to intervene.

If you have an elm tree, talk with one of our arborists about injecting it with a preventative fungicide.