Ulmus minor 'Christine Buisman'

Ulmus minor

'Christine Buisman' Amsteldijk, Amsterdam.
Cultivar 'Christine Buisman'
Origin Netherlands

The Field Elm Ulmus minor 'Christine Buisman' was the first cultivar released by the Dutch elm breeding programme, initiated in response to the less virulent form of Dutch elm disease (DED), Ophiostoma ulmi, which afflicted Europe's elms after the First World War.[1] 'Christine Buisman' was selected from a batch of 390 seedlings grown from seed collected in the Parque de la Quinta de la Fuente del Berro, Madrid, by Mrs Van Eeghen, a friend of elm researcher Johanna Westerdijk, in 1929. [2] Originally identified as Ulmus foliacea (syn. U. minor), it was later treated as Ulmus × hollandica by Melville.[3] However, more recent research in Belgium using DNA markers has reaffirmed 'Christine Buisman' as a clone of U. minor. [4]

Originally identified as clone No. '24', it showed no symptoms of DED after several artificial inoculations. In later years, minor symptoms were detected on both the motherplant and grafted descendants, but these were considered too insignificant to delay its release to commerce as Ulmus 'Christine Buisman' in 1937.

Description

The tree was deemed to have 'no outstanding ornamental characteristics', being 'broadly pyramidal, but 'irregular' in shape, notably the habit of one or two of the main branches initially growing out almost horizontally for about 1 m before curving upwards to the vertical, while outer branches can be long and pendulous.[2] The foliage is dark green.[5][6]

Pests and diseases

Highly resistant to DED,[7] but prone to some strains of Coral Spot fungus Nectria cinnabarina as it lacked resistance mechanisms.[8] In the USA, it also proved very susceptible to Japanese beetles.[5]

Cultivation

The tree had not been thoroughly evaluated in the field before its release. However, such was the clamour for a resistant tree in the Netherlands, nurseries there raised and released large numbers, selling almost 10,000 per annum by the late 1930s. Once its shortcomings, which included poor resistance to sea winds, became apparent, commercial production soon ceased,[9] although by this time it had already been exported to Italy and the USA [8] where it was planted as a street tree. The tree can still be found in the Netherlands, notably in The Hague, and Heiloo, and in the UK at Brighton. In North America, the tree has proved tolerant of heat, drought, and cold. In 1972, 1,000 trees were planted in Kansas City. [10] Hardiness USDA Zone 4 (-20° to -10°F, or -29° to -23° C).[5]

Notable trees

A large specimen planted in 1957 by Bernice Cronkhite in memory of Christine Buisman survives (2010) outside the Cronkhite Graduate Center, Harvard University, USA.[11] A particularly impressive plantation exists in the USA at Buffalo, along McKinley, Chapin, Bidwell, and Lincoln Parkways, as well as Richmond Avenue and in Forest Lawn Cemetery. In the UK, the TROBI Champion is found on Palmeira Avenue, Hove, 12 m high by 38 cm d.b.h. in 2009.[12]

Cultivars

Etymology

The tree is named for Christine Buisman, the first full-time elm researcher (1927-1936) in The Netherlands, who provided the final proof that Graphium ulmi Schwarz (now: Ophiostoma ulmi (Buisman) Melin & Nannf. ) was the causal agent of Dutch elm disease.

Synonymy

Accessions

North America
Europe

Nurseries

References

  1. ↑ Heybroek, H. M. (1993). The Dutch Elm Breeding Program. In Sticklen & Sherald (Eds.)(1993). Dutch Elm Disease Research, Chapter 3. Springer Verlag, New York, USA
  2. 1 2 Morton Arboretum. Ulmus 'Christine Buisman'. Elm cultivars checklist.
  3. ↑ Melville, R. (1978). On the discrimination of species in hybrid swarms with special reference to Ulmus and the nomenclature of U. minor (Mill.) and U. carpinifolia (Gled.). Taxon 27: 345-351
  4. ↑ Cox, K., Vanden Broeck, A., Vander Mijnsbrugge, K., Buiteveld, J., Collin, E., Heybroek, H. M., Mergeay, J. (2013). Interspecific hybridization and interaction with cultivars affect the genetic variation of Ulmus minor and Ulmus glabra in Flanders. Tree Genetics & Genomes Springer-Verlag, Berlin. 2014.
  5. 1 2 3 Koller, G. L. & Dirr, M. A. (1979). Street Trees for Home and Municipal Landscapes. Arnoldia 39-3, p.167, May-June 1979.
  6. ↑ Photograph of 'Christine Buisman' elm. .
  7. ↑ Gibbs, J. N. et al. (1975). Eur. J. Forest Path. 5:161–174.
  8. 1 2 Heybroek, H. M. (1957). Elm breeding in the Netherlands. Silvae Genetica, Vol. 6, No 3-4, pp 112-117, 1957.
  9. ↑ Heybroek, H. M. (1983). Resistant Elms for Europe. In Burdekin, D. A. (Ed.) Research on Dutch elm disease in Europe. For. Comm. Bull. 60. pp 108 - 113.
  10. ↑ Pinney, J. J. (1971). One variety of elm tree is both hardy and lovely. The Kansas City Times, 31 December 1971, p.22.
  11. ↑ Anon. (1958). The Christine Buisman Elm. Radcliffe Quarterly Vol. XLI, February 1958, No. 1. p. 5. Harvard University, USA.
  12. 1 2 Johnson, O. (2011). Champion Trees of Britain & Ireland, p. 168. Kew Publishing, Kew, London. ISBN 9781842464526.
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