To properly eliminate both the beetles and the fungal spores that they transport, treatment for Dutch elm disease necessitates a community-wide effort. A single, isolated tree may be salvaged by cutting away diseased branches and treating bark beetles, but several trees infected with Dutch elm disease may eventually necessitate removal. Landowners who find dead or dying trees should call a tree service to remove them before they cause further damage.
Dutch elm disease is spread by insects that burrow through the bark of elm trees. A fungus is spread from tree to tree by the elm bark beetle. Dark streaks form on the bark as a result of the injury. The disease has had a devastating effect on our native elm stock.
The insect that spreads Dutch elm disease is called the elm bark beetle. It is about 1/4 inch long and dark brown to blackish brown. Female elm bark beetles eat the sapwood of elms, causing the tree to die. They do this in order to make their nests (which are located in the heart of the tree under the cambium layer) out of dead wood so they won't have to compete with other trees for food once winter comes. Once spring comes around again, male elm bark beetles fly into town looking for a female partner. If they find one, they will mate with her and she will feed his larvae corn syrup which makes them bigger and more attractive to birds who then eat them. When the females finally break away from the tree and look for new homes, they can sometimes be found inside buildings where they're trapped against furniture or walls. There they go through several molts (shedding their exoskeletons) until they're large enough to fly off and look for another elm tree to live in.
A fungus causes Dutch elm disease, which is particularly destructive to American and European elms. The fungus wipes off the beetle and proceeds to grow downward in the tree. Once the fungus has infiltrated the root flares, it may spread to neighboring trees via root grafts as well as through the tree itself. Elms are grown for their wood, which is used to make pulp that is then made into paper. So if a tree with Dutch elm disease is cut down, the disease will continue to spread until it kills or rots all the elms.
The most effective way to stop the spread of Dutch elm disease is to avoid planting infected material. This includes seedlings that grow within 1 mile of an infected tree or site and tissue culture plants. As a last resort, you can treat young trees with fungicides but this should be done carefully so as not to harm beneficial insects. There is no cure for Dutch elm disease once it has spread; only eradication can save healthy trees.
Young trees should not be treated with fungicides unless they are inoculated with the Dutch Elm Disease Agent at one time during their life. If an inoculation was not done, then these trees would die after they produced their first generation of seeds. Fungicides are chemicals that kill fungi, so they won't hurt any beneficial insects. However, excessive use of fungicides can cause problems for other organisms, so use them only when necessary.