Dutch elm disease (DED) is one of the most destructive shade tree diseases in North America. The disease affects American elms (and other elm species, to a varying extent), killing individual branches and eventually the entire tree within one to several years. Since its introduction, DED has swept through urban areas, causing tremendous losses of high value American elm street trees. It has also greatly altered the role of elm in bottomland ecosystems. Despite DED, elm remains as a component of natural stands. Trees often survive to seed producing age, but later succumb to the disease. Waves of disease incidence may be related to population fluctuations of the beetles that vector the disease. Elm also remains an important shade tree, and a range of management alternatives are available for high value urban trees.
The USDA Forest Service, Northeastern Area State & Private Forestry, is involved in several projects related to Dutch elm disease. These include:
DED suppression in Washington DC metropolitan area: The USDA Forest Service in Morgantown, West Virginia partners with the DC Urban Forestry Administration, National Park Service, and Casey Trees to suppress DED within the District. Annual cooperative DED citywide surveys and an independent survey by the USDA Forest Service provide information on the status of American elms during the course of this disease. The disease has killed over 25,000 elms since 1950 with only 8,200 elms presently remaining on city streets. Following intensive surveys, elms are slated for either treatments or removal depending on disease severity. Disease resistant elms are often planted as replacement trees. The goal of the current project is to reduce and maintain the annual DED loss at below 2% of the remaining elm population.
American Elm Restoration Plantings: The Northern Research Station has established demonstration plantings of DED-tolerant American elms on multiple sites in Ohio and the Upper Mississippi watershed area of the Midwest. They have also initiated a project with the Chippewa National Forest in Minnesota to develop DED tolerant elms. These projects are further described in briefing sheets for Elm restoration in Ohio, the Upper Mississippi Watershed, and the Chippewa National Forest.
DED images from forestryimages.org
The May 2007 edition of the Central States Forest Health Watch contains a feature article titled "Will elms once again flourish in our forests?"
National Arboretum/ARS has conducted a large amount of research on DED tolerant cultivars of American elm. Alden Townsend, who conducted much of the research, retired in January 2005. One of the most recent tests of elm cultivars for tolerance to DED can be found in a March 2005 research publication in Journal of Environmental Horticulture 23 (1):21-24. It is available on the www at: http://www.elmpost.org/19elms.pdf
Link to the article "Evaluation of elm clones for tolerance to Dutch elm disease" by A. Townsend and L. Douglass in the May 2004 Journal of Arboriculture www.treelink.org/joa/2004/may/townsend5-04.pdf
USDA National Arboretum news release with information on cultivars Valley Forge and New Harmony www.usna.usda.gov/Newintro/american.html
USDA ARS news release with information on cultivar Jefferson www.ars.usda.gov/is/pr/2006/060613.htm
The National Elm Trial web site has information on a national evaluation of DED tolerant elms treehealth.agsci.colostate.edu/research/nationalelmtrial/NationalElmTrial.htm
For an example of a community approach to DED management, see the Minneapolis Park and Recreation Board DED web page at www.minneapolisparks.org/default.asp?PageID=857
The Saskatchewan Dutch Elm Disease Association web page contains links to DED fact sheets from other states and provinces, organizations involved in DED management (particularly in Canada), and links to other articles. www.sdeda.ca
DED web page contacts:
Linda Haugen, St. Paul Field Office
Alan Iskra, Morgantown Field Office