Ulmus davidiana var. japonica 'Prospector'

Elm cultivar

Ulmus davidiana var. japonica 'Prospector'
'Prospector'
Variety	Ulmus davidiana var. japonica
Cultivar	'Prospector'
Origin	National Arboretum, US

The Japanese elm cultivar Ulmus davidiana var. japonica 'Prospector' was originally treated as a cultivar of Wilson's elm U. wilsoniana Schneid., a species sunk as Ulmus davidiana var. japonica by Fu.^[1] A U.S. National Arboretum introduction (NA 55398), it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio, and released without patent restrictions in 1990.^[2] 'Prospector' proved moderately successful in the US National Elm Trial, averaging a survival rate of 76% overall.^[3]

'Prospector' was introduced to the UK in 2009, by Hampshire & Isle of Wight Branch, Butterfly Conservation, as part of an assessment of DED-resistant cultivars as potential hosts of the endangered White-letter Hairstreak.^[4]

Description

'Prospector' is a medium-size elm with a light-grey bark, attaining a height of approximately 14 m and developing a vase shape broadly similar to the American Elm but with lower-drooping branches [3] [4]. The deep-green, glossy obovate leaves are < 11 cm long by 8 cm wide, emerging orange-red and turning yellow in autumn. The perfect, apetalous wind-pollinated flowers emerge in early spring, before the leaves. The samara, 20 mm long by 8–10 mm wide, is narrowly obovate, the seed between centre and notch. Specimens grown in Hampshire, England, first flowered and fruited aged 10 years. The tree was also the first to flower every year, usually by mid-January.^[5]

The tree grows at a comparatively modest pace in the United States; specimens planted at UC Davis as part of the National Elm Trial increased in height by 0.85 m and diameter at breast height by 2 cm in the first few years after establishment ^[6] [5] The species does not sucker from roots.^[7]

'Prospector' emergent leaf colouring.
'Prospector' samarae with £1 coin as scale
'Prospector' samara

Pests and diseases

'Prospector' has featured in several elm trials in the United States, notably those conducted by the Northern Arizona University at Holbrook, eastern Arizona[6], and Townsend & Douglass ^[8] which established that the tree's survival rate after inoculation with the Dutch elm disease pathogen 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.^[9] Moreover, although also highly resistant to elm leaf beetle Xanthogaleruca luteola [7] (no damage whatsoever was recorded in the aforementioned trials at U C Davis ^[6]) 'Prospector' is a favoured food of leaf hoppers which can seriously disfigure foliage by midsummer, and is moderately susceptible to the Japanese Beetle.^[10] Tolerance of Elm Yellows in the United States was found to be poor. However, the disease has proved difficult to transmit experimentally to this cultivar, and there appear to be no natural infections.^[11]

Cultivation

'Prospector' performed well in California, although it "needed substantial training in the first two to three years".^[9] In Arizona, the tree proved unsuited to the hot, arid climate and suffered > 50% leaf scorch. In trials conducted by the University of Minnesota, 'Prospector' was appreciated for its extraordinary vigour but faulted for the weakness of its wood, notably stem breakage owing to bark inclusion.^[12] 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 [8] coordinated by Colorado State University.

'Prospector' was introduced to Europe by Butterfly Conservation in 2009 as part of its elm trials programme in Hampshire but has exhibited very slow growth, its stem increasing by just 2 mm in diameter at breast height per annum.^[5]

The tree was also included in trials in New Zealand undertaken by Hortresearch at Palmerston North in the 1990s.

Synonymy

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

Hybrid cultivars

'Patriot'

Accessions

North America

Arnold Arboretum, US. Acc. no. 134-2002
Bartlett Tree Experts, North Carolina, US. Acc. nos. 2001-261/2/3, 2001–488, 2001-490
Brenton Arboretum, Dallas Center, Iowa, US. 5 trees, acquired 2009. Acc. no. not known.
Dominion Arboretum, Ottawa, Ontario, Canada, No acc. details.
Holden Arboretum, US. Acc. no. 95-141
Morton Arboretum, US. Acc. no. 61–2003, 213-2012
Parker Arboretum, Parker, Colorado, US. No acc. details
Scott Arboretum, US. Acc. no. 91-241
Smith College, US. Acc. nos. 13303, 502
University of Idaho Arboretum, US. Three trees, Acc. nos. 1995011, 1995085
U S National Arboretum, Washington, D.C., US. Acc. no. not known.

Europe

Grange Farm Arboretum, Sutton St James, Spalding, Lincs., UK. Acc. no. 823.
Great Fontley, Fareham, UK. Butterfly Conservation Elm trials plantation, Home Field, one 0.8 m whip planted 2009.
Istituto per la Protezione delle Piante, Florence, Italy. 2 small plants, (2010).
Royal Botanic Garden Edinburgh, UK. Acc. no. 20092086. Listed as U. japonica 'Prospector'.
Sir Harold Hillier Gardens, Romsey, Hampshire, UK. Acc. no. 2009.0454.

Nurseries

North America

(Widely available)

Europe

Pan-global Plants [9], Frampton on Severn, Gloucestershire, UK

References

^ 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, US. [1]
^ HortScience, 26, 81-82, 1991.
^ Griffin, J.; et al. (2017). "Ten-Year Performance of the United States National Elm Trial" (PDF). Arboriculture & Urban Forestry. 43 (3). International Society of Arboriculture, Atlanta, US: 107–120. doi:10.48044/jauf.2017.010.
^ Brookes, Andrew (2020). "Disease resistant elm cultivars" (PDF). Hampshire & Isle of Wight Branch Butterfly Conservation.
^ ^a ^b Brookes, A. H. (2022). Great Fontley Elm Trial, 2022 Report. Butterfly Conservation, Lulworth, England.
^ ^a ^b McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, 32–36.
^ Heybroek, Hans M. (1981). "The Japanese elm species and their value for the Dutch elm breeding program" (PDF). Proceedings of the Dutch Elm Disease Symposium and Workshop, October 5–9, Winnipeg, Manitoba: 78–90.
^ Townsend A. M. & Douglass, L. W. Variation among American Elm Clones in Long-term Dieback, Survival, and Growth Response to Ophiostoma Inoculation
^ ^a ^b 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]
^ Brady, C., Condra, J., & Potter, D. (2008) Resistance of Landscape-suitable Elm (Ulmus spp.) Cultivars to Japanese Beetle, Leaf Miners, and Gall Makers. 2008 Research Report, Nursery & Landscape Program, pp 15, 16. University of Kentucky.
^ Sinclair, W. A., Townsend, A. M., Griffiths, H. M., & Whitlow, T. H. (2000). Responses of six Eurasian Ulmus cultivars to a North American elm yellows phytoplasma. Plant disease, Vol. 84, No.12, 1266–1270. American Phytopathological Society, St. Paul, MN
^ Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota.

External links

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

Elm species, varieties, hybrids, hybrid cultivars and species cultivars

Species, varieties and subspecies

U. alata (Winged elm)
U. americana (American elm)
U. americana var. floridana (Florida elm)
U. bergmanniana (Bergmann's elm)
U. bergmanniana var. bergmanniana
U. bergmanniana var. lasiophylla
U. castaneifolia (Chestnut-leafed or multinerved elm)
U. changii (Hangzhou elm)
U. changii var. changii
U. changii var. kunmingensis (Kunming elm)
U. chenmoui (Chenmou or Langya Mountain elm)
U. chumlia
U. crassifolia (Cedar or Texas cedar elm)
U. davidiana (David or Father David elm)
U. davidiana var. davidiana
U. davidiana var. japonica (Japanese elm)
U. elongata (Long raceme elm)
U. gaussenii (Anhui or hairy elm)
U. glabra (Wych or scots elm)
U. glaucescens (Gansu elm)
U. glaucescens var. glaucescens
U. glaucescens var. lasiocarpa (hairy-fruited glaucescent elm)
U. harbinensis (Harbin elm)
U. ismaelis
U. laciniata (Manchurian cut-leaf or lobed elm)
U. laciniata var. nikkoensis (Nikko elm)
U. laevis (European white elm)
U. laevis var. celtidea
U. laevis var. parvifolia
U. laevis var. simplicidens
U. lamellosa (Hebei elm)
U. lanceifolia (Vietnam elm)
U. macrocarpa (Large-fruited elm)
U. macrocarpa var. glabra
U. macrocarpa var. macrocarpa
U. mexicana (Mexican elm)
U. microcarpa (Tibetan elm)
U. minor (Field elm)
U. minor subsp. minor
U. minor var. italica
U. parvifolia (Chinese or lacebark elm)
U. parvifolia var. coreana (Korean elm)
U. prunifolia (Cherry-leafed elm)
U. pseudopropinqua (Harbin spring elm)
U. pumila (Siberian elm)
U. rubra (Slippery elm)
U. serotina (September elm)
U. szechuanica (Szechuan (Sichuan) or red-fruited elm)
U. thomasii (Rock or cork elm)
U. uyematsui (Alishan elm)
U. villosa (Cherry-bark or marn elm)
U. wallichiana (Himalayan or kashmir elm)
U. wallichiana subsp. wallichiana
U. wallichiana subsp. xanthoderma
U. wallichiana var. tomentosa

Disputed species, varieties and subspecies

U. boissieri
U. minor subsp. canescens (Grey, grey-leafed or hoary elm)
U. elliptica

Hybrids

U. davidiana var. japonica × U. minor
U. × arbuscula
U. × arkansana
U. × brandisiana
U. × diversifolia
U. × hollandica (Dutch elm)
U. × hollandica var. insularum
U. × intermedia
U. × mesocarpa

Species cultivars

American elm	American Liberty Ascendens Augustine Aurea Beaverlodge Beebe's Weeping Brandon Burgoyne JFS Prince II College Columnaris Creole Queen Deadfree Delaware Exhibition Fiorei Flick's Spreader Folia Aurea Variegata Great Plains Hines Incisa Independence Iowa State Jackson Jefferson Kimley Klehmii L'Assomption Lake City Lewis & Clark Littleford Maine Markham Miller Park Minneapolis Park Moline Morden New Harmony Nigricans Patmore Pendula Penn Treaty Princeton Pyramidata Queen City Sheyenne Skinner Upright St. Croix Star Valley Forge Variegata Vase Washington
Cedar elm	Brazos Rim
Chinese elm	A-1 A. Ross Central Park Blizzard BSNUPF Burgundy Burnley Select Catlin Chessins Churchyard Cork Bark D. B. Cole Drake Dynasty Ed Wood Elsmo Emer I Emer II Emerald Prairie Frosty Garden City Clone Geisha Glory Golden Rey Hallelujah Hokkaido Jade Empress King's Choice Littleleaf Lois Hole Matthew Milliken Nire-keyaki Ohio Orange Ribbon Pathfinder Pendens Prairie Shade Prince Richard Red Fall Sabamiki Sagei Seiju Select 380 Sempervirens Small Frye State Fair Stone's Dwarf Taiwan The Thinker Todd True Green UPMTF Ware's Yarralumla Yatsubusa Zettler Ulmus parvifolia f. lanceolata
European white elm	Aureovariegata Colorans Helena Ornata Pendula Punctata Urticifolia
Field elm	Ademuz Albo-Dentata Amplifolia Argenteo-Variegata Atinia Atinia Pyramidalis Atinia Variegata Bea Schwarz Biltii Christine Buisman Concavaefolia Coritana Cretensis Cucullata Cucullata Variegata Dehesa de Amaniel Dehesa de la Villa Dicksonii Dijkwel Erecta Folia Alba-Punctata Glandulosa Goodyeri Hoersholmiensis Holmstruph Hunnybunii Hunnybunii pseudo-Stricta Laciniata Lanuginosa Majadahonda Microphylla Pendula Microphylla Purpurea Microphylla Rubra Monumentalis Pendula Picturata Plotii Propendens Punctata Purpurascens Purpurea Retiro Reverti Rugosa Rueppellii Sarniensis Schuurhoek Silvery Gem Sowerbyi Stricta Suberosa Umbraculifera Gracilis Umbraculifera Viminalis Viminalis Aurea Viminalis Betulaefolia Viminalis Gracilis Viminalis Incisa Viminalis Marginata Viminalis Pendula Viminalis Pulverulenta Viminalis Stricta Virgata Webbiana
Japanese elm	Discovery Freedom Jacan JFS-Bieberich Mitsui Centennial Prospector Reperta Reseda Thomson Validation
Siberian elm	Ansaloni Aurea Aurescens Chinkota Dropmore Dwarf Weeper Green King Hansen Harbin Manchu Mauro Mr. Buzz Park Royal Pendula Pinnato-ramosa Poort Bulten Puszta Pyramidalis Fiorei Zhonghua Jinye
Winged elm	Lace Parasol
Wych elm	Albo-Variegata Australis Camperdownii Cebennensis Concavaefolia Cornuta Corylifolia Purpurea Corylifolia Dovaei Fastigiata Macrophylla Fastigiata Stricta Fastigiata Variegata Firma Flava Gigantea Gittisham Grandidentata Holgeri Horizontalis Insularis Latifolia Latifolia Aurea Latifolia Aureo-Variegata Latifolia Nigricans Luteo Variegata Lutescens Macrophylla Maculata Minor Nana Nigra Nitida Oblongata Pendula Macrophylla Pendula Variegata Pyrenaica Spectabilis Superba Tomentosa

Hybrid cultivars

Androssowii Amsterdam Arno Cathedral Clusius Columella Den Haag Dodoens Escaillard Fiorente Frontier Fuente Umbria Homestead Karagatch Lobel Morfeo Morton Morton Glossy Morton Plainsman Morton Red Tip Morton Stalwart Nanguen New Horizon Patriot Plantyn Plinio Rebella Rebona Recerta Regal Repura Revera San Zanobi Sapporo Autumn Gold Sapporo Gold 2 Stavast Toledo Urban Wanoux Wingham
Dutch elm	Alba Angustifolia Balder Belgica Blandford Canadian Giant Cicestria Cinerea Commelin Dampieri Dauvessei Daveyi Dumont Elegantissima Eleganto-Variegata Etrusca Fastigiata Fjerrestad Folia Rhomboidea Freja Fulva Gaujardii Groeneveld Haarlemensis Klemmer Loke Macrophylla Aurea Major Microphylla Modiolina Muscaviensis Odin Pioneer Pitteurs Serpentina Smithii Superba Tricolor Tyr Vegeta Viminalis Viscosa Wentworthii Pendula Wredei Ypreau
U. × intermedia	Coolshade Fremont Improved Coolshade Lincoln Rosehill Willis