Sapporo Autumn Gold (elm hybrid)
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| Ulmus Sapporo Autumn Gold |
|---|
 |
| Hybrid parentage |
| Ulmus pumila × Ulmus davidiana var. japonica |
| Cultivar |
| Sapporo Autumn Gold |
| Origin |
| seeds:Sapporo, Japan; culivated: USA |
The hybrid elm Sapporo Autumn Gold has proven one of the most successful yet marketed, and has been widely planted across North America and western Europe. Arising from a chance crossing of the Siberian Elm U. pumila and the Japanese Elm U. davidiana var. japonica in the Botanical Garden of Hokkaido University, Sapporo, it was cultivated at the University of Wisconsin by Dr Eugene Smalley.
The tree forms a densely foliated vase-shaped crown, although immature plants produce vigorous side shoots that require assiduous pruning to develop the desired shape. As its name implies, its dark green leaves turn pale yellow in autumn, resembling those of the female parent, U. pumila, being comparatively small and narrow; flowering and fruiting occur in spring.
In favourable conditions, notably a moist, well-drained soil, the tree can grow at a rate of almost one metre per annum, but trials by the Northern Arizona University [1] found that it is not very tolerant of a hot, arid environment although its leaves sustain comparatively little scorch damage.
Sapporo Autumn Gold possesses a high resistance to Dutch elm disease although it is not immune. It remains popular in Europe, where it is raised under licence by the Conrad-Appel nursery in Darmstadt, Germany, as one of the Resista series along with its Wisconsin siblings New Horizon and Cathedral. However, dissimilar to native European elms, it does not assimilate well in the countryside. Moreover, in trials in France by Cemagref at Nogent sur Vernisson, Loiret, it was found to grow too vigorously in hedgerow conditions, eclipsing the adjoining shrubs and consequently creating gaps. Nevertheless, it has been found to make an acceptable host for the endangered White-letter Hairstreak butterfly Satyrium w-album, whose larvae feed exclusively on elm. A good example (shewn above, right) of Sapporo Autumn Gold is grown at the Sir Harold Hillier Gardens in Hampshire, England. The hybrid was also included in trials [2] in Canberra, Australia started in 1988, but has not performed well there.
[edit] References
- Brookes, A. H. (2006). An evaluation of disease-resistant hybrid and exotic elms as larval host plants for the White-letter Hairstreak butterfly Satyrium w-album. Part 1. Butterfly Conservation, Lulworth, UK.
- Burdekin, D. A. & Rushforth, K. D. (Revised by Webber J. F. 1996). Elms resistant to Dutch elm disease. Arboricultural Research Note 2/96. Arboricultural Advisory and Information Service, Alice Holt, Farnham, UK.
- Cornell University: Elm hybrids (pdf file)
- Santamour, J., Frank, S. & Bentz, S. (1995). Updated checklist of elm (Ulmus) cultivars for use in North America. Journal of Arboriculture, 21:3 (May 1995), 121-131. International Society of Arboriculture, Champaign, Illinois, USA.
- Smalley, E. B. & Guries, R. P. (1993). Breeding Elms for Resistance to Dutch Elm Disease. Annual Review of Phytopathology Vol. 31 : 325-354. Palo Alto, California.
