Ulmus davidiana var. japonica 'Prospector'

Infobox Cultivar | name = "Ulmus davidiana" var. "japonica"
cultivar = 'Prospector'
origin = National Arboretum, USA
synonyms =The Japanese Elm "Ulmus davidiana" var. "japonica" cultivar 'Prospector' was formerly treated as a cultivar of Wilson's Elm "U. wilsoniana" Schneid., now sunk as "U. davidiana" var. "japonica" by Fu Fu, L., Xin, Y. & Whittemore, A. (2002). Ulmaceae, in Wu, Z. & Raven, P. (eds) "Flora of China", Vol. 5 (Ulmaceae through Basellaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, USA. [http://flora.huh.harvard.edu/china/PDF/PDF05/Ulmus.pdf] ] . A U.S. National Arboretum introduction, it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio, and released in 1990 "HortScience", 26, 81-82, 1991.] .

Description

'Prospector' is a medium-size tree with a light-grey bark, quickly attaining 14 m in height and developing a vase shape broadly similar to the American Elm but with lower-drooping branches [http://www.sunshinenursery.com/elms.htm] . The deep-green, glossy leaves are < 110 mm long by < 80 mm wide, emerging orange-red and turning yellow in autumn.

Pests and diseases

'Prospector' has been featured in several elm trials in the USA, notably those conducted by the Northern Arizona University at Holbrook, eastern Arizona [http://www.for.nau.edu/cms/content/view/512/706/] , and Townsend & Douglass Townsend A. M. & Douglass, L. W. "Variation among American Elm Clones in Long-term Dieback, Survival, and Growth Response to OphiostomaInoculation"] which established that the tree's survival rate after inoculation with the Dutch elm disease fungus was 100%. In trials in California, the tree exhibited a singular sensitivity to boron concentrations of > 200 ppm in the soil, causing marginal necrosis on the leaves Costello, L. R. (2004). A 10-year evaluation of the performance of four elm cultivars in California, U.S. "Journal of Arboriculture", March, 2004. [http://www.findarticles.com/p/articles/mi_qa4107/is_200403/ai_n9387070/print] ] . Moreover, although also highly resistant to elm leaf beetle "Xanthogaleruca luteola" [http://commons.wikimedia.org/wiki/Xanthogaleruca_luteola] and Elm Yellows, 'Prospector' is a favoured food of leaf hoppers which can seriously disfigure foliage by midsummer.

Cultivation

'Prospector' performed well in California, although it "needed substantial training in the first two to three years". In Arizona, the tree proved unsuited to the hot, arid climate and suffered more than 50 % leaf scorch, but in trials conducted by the University of Minnesota, 'Prospector' was appreciated for its extraordinary vigour, although faulted for the weakness of its wood, not least because of stem breakage owing to bark inclusion Giblin, C. P. & Gillman, J. H. (2006). "Elms for the Twin Cities: A Guide for Selection and Maintenance." University of Minnesota.] . Nonetheless, it is considered by the U.S. Department of Agriculture (USDA) as suitable for Zones 4 - 7. The tree is currently being evaluated in the National Elm Trial [http://treehealth.agsci.colostate.edu/research/nationalelmtrial/NET_Cultivars.htm] coordinated by Colorado State University.

The tree was released for sale in the UK in 2008, and also featured in trials in New Zealand undertaken by Hortresearch at Palmerston North in the 1990s.

ynonymy

"Ulmus wilsoniana" C. K. Schneid. 'Prospector'

Hybrid cultivars

*'Patriot'

Accessions

;North America
*Arnold Arboretum acc. no. 134-2002.
*Bartlett Tree Experts, North Carolina acc. nos. 2001-261/2/3, 2001-488, 2001-490.
*Holden Arboretum acc. no. 95-141.
*Morton Arboretum acc. no. 61-2003.
*Scott Arboretum acc. no. 91-241.
*Smith College acc. nos. 13303, 502.

Nurseries

;North America(Widely available);Europe
*Golden Hill Plants [http://www.goldenhillplants.com/] , Marden, Kent, UK

References

External links

*http://www.extension.iastate.edu/Publications/SUL4.pdf Summary, inc. photographs, of elm cultivars resistant to Dutch elm disease available in the USA.
*http://www.usna.usda.gov/Newintro/prospect.pdf Prospector, USNA information sheet.