Almost all metropolitan areas in the U.S. with viable American elm tree populations have been affected by Dutch elm disease, including Minneapolis, St. Paul, and the surrounding Twin Cities suburbs. First reported in the U.S. in 1928, the lethal tree disease has spread to most large U.S. cities, destroying millions of beautiful American elm trees in its wake.
How does Dutch elm disease spread?
Dutch Elm Disease is spread primarily by one species of elm bark beetle. Elm bark beetles are capable of crossing boulevards, rivers, parks, etc. Dutch Elm Disease can also spread from diseased to healthy trees through root grafts that form when neighboring trees’ roots come in contact in the soil. Dutch elm disease may even be spread by pruning equipment that was used on a contagious, diseased tree.
CAUTION: If you have healthy elm trees, be very careful about the company you choose to prune, trim, or remove your trees. Make sure they follow industry standards in terms of how and when they clean their equipment, and ask them what steps they take to ensure that they do not spread any tree diseases.
How does Dutch elm disease kill an elm tree?
Although the elm bark beetle can transmit the disease, the beetle itself does not kill the tree. The cause of Dutch elm disease is a fungus carried by the beetle which infects the trees’ water conducting (or vascular) system. This prevents water and nutrients from getting up to the crown (top area) of the tree, causing the infected elm tree to wilt, then die.
What are the symptoms?
The first symptom of Dutch elm disease is a yellowing and withering of leaves. This may happen on the crown at the end of the branches, or it may appear on one side of the tree if the tree has been infected through roots grafted to an infected elm tree nearby. Inspect your elm tree regularly. If it shows symptoms of wilting during the summer, well ahead of the time that leaves normally turn color and drop, this could mean trouble. Trees infected the previous year will have these symptoms early in the summer. The yellowing and withering of leaves will spread, sometimes quickly, or it may happen over a period of years.
What can be done to treat Dutch Elm Disease?
There are a number of Dutch elm disease management tools. The most universally important is sanitation - finding and removing infected trees before they become contagious. There are also specific measures that can be taken to protect individual trees. Most cost-effective among them is direct infusion of systemic fungicides. Note that treating this disease is the job of certified arborists; they are trained in tree diseases and they have the right equipment and processes.
The job of the arborist is to interrupt the disease cycle by employing a number of methods. Methods include root graft disruption, fungicide injections, pruning, and/or removal of contagiously infected trees. Methods will vary depending on the location and/or spread of the fungus. Procedures must be specifically matched to your circumstances and carefully conducted.
Unfortunately, Dutch elm disease in the Twin Cities area is a reality. Rely on our ISA Certified Arborists® and tree experts for professional analysis and treatment of Dutch Elm Disease in Minneapolis, St. Paul, or the greater Twin Cities area of Minnesota.