Dutch Elm Disease
Dutch Elm Disease is a lethal tree disease caused by an aggressive fungus. The disease is primarily transmitted by a beetle that feeds in the 2 to 4-year-old branches. It is the most destructive and costly disease of elms in North America! The first infections in North America were identified in Ohio in 1930. Dutch Elm Disease was introduced to the United States from Europe in logs that contained both the fungus and the smaller European elm bark beetle. It has now spread throughout North America and has been reported in all states except those in the desert Southwest. Minnesota's first case of Dutch Elm Disease was detected in St. Paul in 1961, and has been reported in nearly all of Minnesota's 87 counties.
This aggressive fungus is unable to be contained by the tree and the tree eventually will wilt and die. The first symptoms of Dutch Elm Disease is the wilting of the leaves on one or a few branches in the upper canopy of the tree. The stage is termed flagging as the affected leaves first turn yellow or brown and then shrivel. These leaves may fall from the tree prematurely. Sometimes the leaves dry out very quickly, turning dull green or brown, and can remain hanging on the branches for weeks or even months before falling. As the disease progresses, often at a rapid rate, the affected branches die and more of the tree becomes infected.
How does the disease infect healthy trees? The most common method of transmission of Dutch Elm Disease is on the bodies of the elm bark beetle. Female elm bark beetles lay their eggs beneath the bark of the dead and dying elm trees. If the elm is infected with Dutch Elm Disease, the newly hatched beetles will emerge from the tree carrying the deadly fungus on their bodies. The beetles fly to healthy trees to feed in 2 to 4-year-old branches and thereby spread the disease.
- 2 to 3 generations of bark beetles hatch each year
- thousands of beetles may hatch from a single tree
Besides beetle transmission, Dutch Elm Disease may also spread through grafted roots. When elms grow in close proximity to each other (crowns touching), their roots come into contact and graft together. This common root system provides the fungus with a path to spread through an entire stand of healthy elms very quickly.
A Dutch Elm Disease Control Program will be successful only if organized on a community-wide basis with the involvement and cooperation of property owners. The prompt removal and proper disposal of all dead and dying elm wood with intact bark is the single most important tool in combatting Dutch Elm Disease. Monticello's Program consists of the following disease management practices:
- Annual Inspections - During the growing season, frequent inspections throughout the community are necessary to detect diseased elms early enough to reduce the spread of the disease. These inspections help locate elm firewood, elm stumps, and dead elm trees that may provide suitable breeding material for the elm bark beetles. The identification of diseased elms will be done by the City Tree Inspector. Diseased or dying elm trees (or wood piles) will be marked with a painted (green) X and green tape. Homeowners/property owners are to remove only the trees which have been identified as diseased, and for which a notification document has been issued by the City Tree Inspector.
- Immediate Removal of Infected Elms - It is the responsibility of the property owner to remove or to contract the removal of the diseased elm tree(s) within 20 days of notification. The removal date for the tree(s) is indicated on the notification document. It is necessary for you to contact the Monticello Parks Department at 763-295-2711 immediately upon receiving a notice in the mail.
- Proper Disposal - All elm wood must be properly disposed of to eliminate the breeding site for elm bark beetles. Any elmwood piles must be chipped or debarked. Any stumps remaining must be debarked. Property owners may haul branches to the curbside and contact the City to request the curbside chipping service for a minimal fee. Debarked elm wood may be used for firewood.
In an effort to assist property owners with urban reforestation, the City of Monticello offers a Tree Replacement Program. So for each elm tree, you've been ordered to remove and have properly removed, you may purchase a new tree the following spring and provide the City with a receipt of that purchase. We will reimburse you half the cost of the tree(s) up to $30. Monticello's Annual Spring Tree Planting Program is a great way to purchase nursery quality bare root trees for a low cost.
Monticello's urban forest is a valuable natural resource that must be preserved and maintained to provide a better quality of life for present and future generations. In an effort to maintain the vitality of the community's urban forest, the City of Monticello established a Shade Tree Disease Control Program to help control shade tree diseases in our parks and throughout our community. The City's Tree Inspector is responsible for the coordination of the Shade Tree Disease Program. Primary duties include the identification and control of Oak Wilt and Dutch Elm Disease infected trees on public and private property. A key aspect of this position is the direct communication and coordination of shade tree disease control efforts with the general public.
As a property owner, you can help control the spread of Dutch Elm Disease by checking your neighborhood for dead or dying elm trees and by checking your woodpile for elm wood with intact bark. If you are not sure if your woodpile contains elm wood or you suspect there are dead or dying elm trees in your neighborhood, please contact the Monticello Parks Department at 763-295-2711.