Ulmus 'Sapporo Autumn Gold'

Ulmus hybrid
Sapporo Autumn Gold, Mudeford, Dorset, UK, planted 1985.
Details
Hybrid parentage	U. pumila × U. davidiana var. japonica
Cultivar	'Sapporo Autumn Gold'
Origin	seeds: Sapporo, Japan; cultivated: USA

'Sapporo Autumn Gold' is one of the most successful hybrid elm cultivars ever marketed, widely planted across North America and western Europe, although it has now been largely supplanted by more recent introductions.^[1] Arising from a chance crossing in 1958 of the Siberian Elm Ulmus pumila and the Japanese Elm Ulmus davidiana var. japonica in the Botanical Garden of Hokkaido University, Sapporo, it was cultivated at the University of Wisconsin–Madison by the late Prof. Eugene Smalley and patented in 1975.^[2][3]

Description

The tree usually forks at between 1.5 m and 2 m from the ground to produce a broad, rounded, densely foliated crown, although immature plants produce vigorous side shoots that require assiduous pruning to develop the desired shape. The bark is pale grey, and longitudinally fissured to form a random lattice pattern. The leaves are narrowly-elliptical, < 9 cm long by < 4.5 cm wide, with 8 mm petioles. As the name implies, the leaves turn pale yellow in autumn.^[4] The perfect, apetalous wind-pollinated flowers appear in early March, followed by the seeds in April; flowering usually begins when the tree is aged six years.

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  Bark of 30-year old tree.

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  Sapporo Autumn Gold foliage.

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  Sapporo Autumn Gold leaf with 1 Euro coin.

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  Largest known Sapporo A G in Europe, near Florence

Pests and diseases

'Sapporo Autumn Gold' possesses a very high resistance to Dutch elm disease ^[5][6] and a tolerance of Verticillium wilt.^[7] The tree's foliage was adjudged "resistant" to Black Spot by the Plant Diagnostic Clinic of the University of Missouri [4], however it can be severely damaged the Elm Leaf Beetle Xanthogaleruca luteola in the USA [5]

Cultivation

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 [6] found that it is not very tolerant of a hot, arid environment although its leaves sustain comparatively little scorch damage. In trials in southern England conducted by Butterfly Conservation, the tree was found to be intolerant of ponding over winter.^[8]

'Sapporo Autumn Gold' was first introduced to the UK by technology company Pitney Bowes as part of its 'Elms Across Europe' campaign. The company supplied the cultivar to schools, parks and gardens throughout the UK and Europe.^[9] The tree remains popular in continental Europe but does not assimilate well in the countryside. In trials in France by Cemagref at Nogent-sur-Vernisson, Loiret, it was found to grow too vigorously in hedgerow conditions, eclipsing neighbouring shrubs and consequently creating gaps. Planted in Northamptonshire, England, it was found to make an acceptable host for the endangered White-letter Hairstreak butterfly Satyrium w-album, whose larvae feed exclusively on elm ^[10] The hybrid was included in trials [7] in Canberra, Australia started in 1988, but has not performed well there.

Notable trees

The very first tree planted in the UK in 1979, at Pitney Bowes by Denis Thatcher, survives (2011) in perfect health [8]. Other notable plantings were as street trees across Bexhill-on-Sea, East Sussex in late 1980s, as riverside trees along the Ouse in York (from Lendal Bridge to Clifton Ings).

Synonymy

• Shapiro Autumn Gold: Whitcomb, C. E. Know it and grow it, p. 171, 1976, missprint for 'Sapporo'.

Accessions

North America

• Bartlett Tree Experts. Acc. nos. 88-1153, 88-1154
• Dominion Arboretum, Ottawa, Canada. No acc. details.
• Holden Arboretum. Acc. no. 91-79

Europe

• Arboretum de La Petite Loiterie [9], Monthodon, France. No details available.
• Brighton & Hove City Council, UK, NCCPG Elm Collection [10]. Examples in Blaker's Park, Stanmer Park, Preston Park and Woodvale cemetery.
• Cambridge Botanic Garden [11], University of Cambridge, UK. No accession details available.
• Great Fontley Farm, Fareham, UK, Butterfly Conservation Elm Trials plantation, Home Field.
• National Botanic Gardens [12], Glasnevin, Dublin, Ireland. Location: A3 (158).
• Royal Botanic Garden Wakehurst Place, UK. Acc. no. 1987-4028.
• Royal Horticultural Society Gardens Wisley, UK, no details available.
• Sir Harold Hillier Gardens, Romsey, Hampshire UK. Acc. no. 1981.1753.
• Thenford House Arboretum, Thenford, UK. No details available.
• University Parks, Oxford, UK. Acc. no. 02565, 02566.
• Westonbirt Arboretum [13], Tetbury, Glos., UK. Planted 1981, acc. no. 1980/159.
• Writtle College, Writtle, Essex, UK. No accession details available.

Australasia

• Waite Arboretum [14], University of Adelaide, Adelaide, Australia. Acc. nos. 572, 598

References

1. ^ 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.
2. ^ Smalley, E. B. & Lester, D. T. (1973). HortScience 8: 514-515, 1973.
3. ^ 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.
4. ^ Photograph of autumn colouring of 'Sapporo' elm, [1].
5. ^ Pinon, J., Lohou, C. & Cadic, A. (1998). Hybrid Elms (Ulmus Spp.): Adaptability in Paris and behaviour towards Dutch elm disease (Ophiostoma novo-ulmi). Acta Horticulturae 496, 107-114, 1998.
6. ^ Pinon, J. (2007). Les ormes résistants à la graphiose. Forêt-entreprise, No. 175 - Juillet 2007, p 37-41, France.
7. ^ 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.
8. ^ Brookes, A. H. (2010). Disease-resistant elm cultivars: Butterfly Conservation trials report, 2010. Butterfly Conservation, Hants & IoW Branch, England. [2]
9. ^ Great British Elm Experiment website, with photograph of one of the original Pitney Bowes' 'Sapporo Autumn Gold' elms: [3]
10. ^ Davies, M.(1984). White-letter Hairstreak Project. Newsletter No. 12, Winter 1984/85, West Midlands Branch, Butterfly Conservation.