American Liberty (elm cultivar)
From Wikipedia, the free encyclopedia
| Ulmus americana |
|---|
| Cultivar |
| American Liberty |
| Origin |
| ERI, USA |
The American Elm cultivar American Liberty is in fact a group of six genetically distinct cultivars under a single name, although they are superficially similar. Promoted exclusively by the Elm Research Institute (ERI) [1] since 1983, these trees have been planted across the United States in numbers which that organization claims to be in excess of 250,000. The six clones which comprise this series vary considerably in their level of resistance to Dutch elm disease, and none is immune, but some evidence suggests that at least one of the six clones may have a fairly high degree of DED-resistance [2]. It is claimed, controversially, by ERI that fewer than 180 American Liberty elm trees have been known to succumb to DED since the planting began in the early 1980's.
The Liberty elm is reportedly suitable for street planting, being tolerant of de-icing salts and air pollution. However, examples included in 10-year trials at Atherton, California to evaluate replacements for Californian elms lost to disease did not perform well. With careful pruning they assumed the typical American Elm form and grew very rapidly; however, they proved vulnerable to disease, wind damage in winter, and high levels of injury from elm leaf beetles. Accordingly, the cultivar was deemed "highly questionable as a replacement" (Costello, 2004). Moreover, the American Liberty elms were noted as being highly susceptible to elm yellows (phloem necrosis) in New York (Sinclair et al., 1994). Examples tested by research scientists at the United States National Arboretum in the 1992-1993 also failed to perform well [3]; but unfortunately, it has never been clear which of the six clones were represented in the tests, so the results remain largely inconclusive.
Contents |
[edit] Arboreta etc. accessions
[edit] North America
- Dominion Arboretum [4], Canada, no details available.
- Holden Arboretum, acc. no. 84-336, two trees > 13 m in height (2006).
- Scott Arboretum, acc. no. 84-276.
[edit] Europe
None known.
[edit] Nurseries
[edit] North America
(Widely available)
[edit] Europe
None known.
[edit] References
- Costello, L. R. (2004). A 10 -year evaluation of the performance of four elm cultivars in California, U. S. Journal of Arboriculture, March 2004. [5]
- Sinclair, W. A., Griffiths, H. G., & Lee, I-M., Journal of Arboriculture. 20: 176-189, 1994.
- Townsend, A. M., Bentz, S. E., and Douglass L. W. (2005). Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease. Journal of Environmental Horticulture, March 2005, Horticultural Research Institute, Washington, D.C.
- Footnote About the Liberty Elms
[edit] External links
- http://www.landscapeelms.com/NL%20SUMMER-05.pdf Liberty Elms in USA
