Released September 14, 2009
ST. PAUL, Minn. — Since 1999, the University of Minnesota has been cooperating with the Minneapolis Park and Recreation Board to evaluate and select elms for use in Minnesota. Many new Hybrid and American elms are resistant to Dutch elm disease (DED); they are available and should be reliably hardy in USDA Hardiness Zone 4 given proper care.
Elms in general, require considerably more pruning and training than other landscape trees. This problem can be exacerbated under high fertility conditions, which is often the case in home lawns. The first 10 years of a tree’s life often determines how it will perform for the remainder of its life. In the case of elms, a small investment in maintenance during the formative years will have a huge payoff when it is approaching maturity.
Like most trees, these elms are best maintained with a strong central leader (a strong, columnar stem reaching to the top of the tree). This ensures a straight stem and keeps the tree growing up rather than out. As the lower side branches grow and increase in diameter, they should be removed until the desired clearance for the site is reached. If the tree is on residential or commercial property away from streets, branches may only need to clear about 8 to 10 feet.
Knowing when and how much to prune and maintain trees requires experience. If you’re not sure how to work on young trees, be sure to contact an ISA Certified Arborist to get you started right. The investment made now will pay off when your tree is growing beautifully and providing shade on your property.
Diversifying our landscape with many different varieties of trees helps to create a sustainable ecosystem. The American elm varieties offer excellent potential for use in rural windbreaks without the potential for invasiveness sometimes found in the hybrid elms. These DED-resistant elms add to our array of tree species that can be planted in the upper Midwest, which contributes to making our communities greener, sustainable and cooler!
To learn more about these new DED-resistant elm trees look at the following websites:
- University of Minnesota Extension Yard and Garden articles on DED and Resistant Elm Tree varieties http://www.extension.umn.edu/projects/yardandgarden/YGLNews/YGLNewsJuly12007.html
- Urban Forestry & Horticulture Research Institute (TRĒ Nursery): http://www.tre.umn.edu
- DED symptoms information from Extension: http://www.extension.umn.edu/projects/yardandgarden/diagnostics/ded.html
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http://www.extension.umn.edu/extensionnews/2009/elm-care-fall.html
Sources: Chad Giblin is a scientist with U of M Department of Horticultural Science; Jeff Gillman is an associate professor with U of M Department of Horticultural Science; Gary Wyatt and Diomy Zamora are natural resources educators with U of M Extension.
Media contact: Catherine Dehdashti, (612) 625-0237, ced@umn.edu
