| Ulmus americana 'Delaware' | |
|---|---|
 Delaware Elm, USDA Washington | |
| Species | Ulmus americana |
| Cultivar | 'Delaware' |
| Origin | USDA, Morristown, New Jersey, US |
The American Elm cultivar Ulmus americana 'Delaware' was originally selected (as tree number 218, a c.1940 seedling from North Dakota) from 35,000 seedlings inoculated with the Dutch elm disease fungus in USDA trials at Morristown, New Jersey.[1]
Description[edit]
The tree has a relatively low stature and "undesirable" branching habit.[1][2]
Pests and diseases[edit]
Further disease-resistance trials were conducted by both the USDA and the United States National Arboretum which confirmed the clone had a fair level of resistance to Dutch elm disease. 'Delaware' is susceptible to Elm Yellows, but resistant to the Elm Leaf Beetle Xanthogaleruca luteola.
Cultivation[edit]
The original tree, which had been moved to the USDA National Arboretum, Washington, D. C. in 1948, died from unknown causes (probably elm yellows, by some accounts) in 1980, but a clone survives at the Denver Botanic Gardens, as 'Delaware II'. Seven specimens stand in the National Mall area, Washington D.C.[3][4] [5] Although propagated for further trials, the tree was never commercially released owing to its poor shape. 'Delaware' is not known to have been introduced to Europe or Australasia.
-
'Princeton' elms on right, planted 1920s; 'Delaware' on left, planted in 1983, in a side allée of the Washington Road Elm Allée, Princeton, New Jersey, US (2011)
Synonymy[edit]
- 'Delaware II'.
NB 'Delaware I' is the original name given to the hybrid 'Urban' before its commercial release.
Accessions[edit]
North America[edit]
- Brooklyn Botanic Garden, [1] Archived 2016-02-01 at the Wayback Machine, New York, US. Acc. no. 980489.
- Dawes Arboretum, US. [2], Newark, Ohio, US. 1 tree, listed as 'Delaware #2'; no acc. details available.
- Denver Botanic Gardens, US. No details available.
- Dominion Arboretum, Canada. [3]. No details available.
References[edit]
- ^ a b Santamour, Frank S.; Bentz, Susan E. (May 1995). "Updated Checklist of Elm (Ulmus) Cultivars for use in North America". Journal of Arboriculture. 21 (3): 122–131. Retrieved 20 June 2016.
- ^ 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.
- ^ 'Delaware', Smithsonian Gardens, si.gardenexplorer.org
- ^ 'Delaware' before pruning, National Museum of Natural History, Constitution Avenue NW, Washington DC - Google Maps, March 2011, access date: 18 October 2022
- ^ Pruned 'Delaware', National Museum of Natural History, Constitution Avenue NW, Washington DC - Google Maps, August 2022, access date: 17 October 2022