American Liberty (elm cultivar)

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The American Elm U. americana American Liberty is in fact a group of six genetically different cultivars, although they are outwardly identical. Promoted by the Elm Research Institute (ERI) [1] since 1983, over 300,000 have now been planted across the USA. The tree is not immune to Dutch elm disease, but moderately resistant, and the ERI claims that fewer than 180 trees have succumbed since the planting programme began. The Liberty elm is reputed to be particularly 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. Whilst with careful pruning they assumed the typical American Elm form, and grew very rapidly, 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).

American Liberty is not known to be in cultivation in Europe or Australasia.

[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. [2]
• 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.