Prospector (elm cultivar)

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The Japanese Elm 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, 2002). A U.S. National Arboretum introduction, it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio,and released in 1990. It 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 [1]. The deep-green, glossy leaves are <110 mm long by <80 mm wide, emerging orange-red and turning yellow in autumn.

Highly resistant to Dutch elm disease, elm leaf beetle, and elm yellows, it has accordingly featured in several elm trials in the USA, notably those conducted by the Northern Arizona University at Holbrook, eastern Arizona [2], and in California by Costello (Costello, 2004). In the Arizona trials however, it generally proved unsuited to the hot, arid environment, and experienced more than 50 % leaf scorch. It performed better in the California trials although it "needed substantial training in the first two to three years", and also exhibited a particular sensitivity to boron in the soil, causing marginal necrosis on the leaves. It is considered by the U.S. Department of Agriculture (USDA) as suitable for Zones 4 - 7.

Prospector can be easily propagated from softwood cuttings under mist, usually rooting within three or four weeks. It was crossed with the American hybrid cultivar Urban by the USDA in 1980 to create the hybrid cultivar Patriot.

Prospector is not known to be in cultivation in Europe, but featured in trials in New Zealand undertaken by Hortresearch at Palmerston North in the 1990s.

[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. [3]
HortScience, 26, 81-82, 1991.