“Ulmus 'Homestead'”的意思、由来-开放百科全书

Ulmus 'Homestead' is an American hybrid elm cultivar raised by Alden Townsend of the United States National Arboretum at the Nursery Crops Laboratory in Delaware, Ohio. The cultivar arose from a 1970 crossing of the Siberian Elm Ulmus pumila (female parent) with the hybrid N 215 ('Commelin' × (U. pumila 'Pinnato-ramosa' × U. minor 'Hoersholmiensis')), the latter grown from seed sent in 1960 to the University of Wisconsin-Madison elm breeding team by Hans Heybroek of the De Dorschkamp Research Institute in the Netherlands. 'Homestead' was released to commerce without patent restrictions in 1984.

Description

The tree rapidly produces very upright growth, increasing in height by as much as 2 m per annum,^[1] forming a pyramidal crown bearing dark green leaves < 7 cm long by 3.5 cm broad which turn straw yellow in autumn; the bark is dark grey.^[2] The perfect, apetalous wind-pollinated flowers appear in early March. The tree's ultimate height should be around 20 m, with a spread of 12 m.^[3]^[4]

Pests and diseases

'Homestead' has a high resistance, rated 4–5 out of 5,^[5] to Dutch elm disease, but can be heavily to severely damaged by the Elm Leaf Beetle Xanthogaleruca luteola ^[6] ^[1]

and Japanese Beetle^[7] in the US. 'Homestead' appears highly resistant to Elm Yellows,^[8] and was adjudged "resistant" to Black Spot by the Plant Diagnostic Clinic of the University of Missouri .

Cultivation

The tree proved intolerant of hot and arid conditions in eastern Arizona, where it exhibited high (> 50%) of dieback in trials conducted by Northern Arizona University . Trials conducted by the University of Minnesota confirmed the tree's susceptibility to sun scorch, and its vulnerability to cambial damage over winter, although neither failing appeared to affect its long-term performance.^[9] The tree is currently being evaluated in the National Elm Trial [https://web.archive.org/web/20080226012323/http://treehealth.agsci.colostate.edu/research/nationalelmtrial/NET_Cultivars.htm] coordinated by Colorado State University.

'Homestead' has had a limited introduction to Europe;^[10] experimental plantings were made along streets in Brighton, England, and in several Dutch cities, notably Beethovenstraat in Amsterdam, along the N360 at Ten Boer, and the Ijsselstraat at Hengelo.^[5] However, many of the Netherlands trees have since been replaced by the more DED-resistant 'Columella'. The tree also featured in trials in New Zealand during the 1990s at the Hortresearch station, Palmerston North.

'Homestead' is very easily propagated from hardwood cuttings taken in February, placed in a 50:50 vermiculite / perlite medium and subjected to a bottom heat of @ 18°C.

Notable trees

The largest specimens in the UK are to be found at Preston Park, Brighton, measuring 9 m high by 25 cm d.b.h. in 2009.^[11]

Accessions

Nurseries

References

1. ^¹McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, 32–36.
2. ^Photograph of 'Homestead' elm, .
3. ^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, US.
4. ^Townsend, A. M. & Masters, W. O., HortScience, 19: 897-898, 1984.
5. ^¹Heybroek, H. M., Goudzwaard, L, Kaljee, H. (2009). Iep of olm, karakterboom van de Lage Landen (:Elm, a tree with character of the Low Countries). KNNV, Uitgeverij. {{ISBN|9789050112819}}
6. ^{{Cite web|url=http://www.sunshinenursery.com/survey.htm|access-date=17 July 2017|archiveurl=https://web.archive.org/web/20110719132152/http://www.sunshinenursery.com/survey.htm|title=Elm Leaf Beetle Survey|archive-date=2011-07-19}}
7. ^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, 15–16. University of Kentucky.
8. ^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
9. ^Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota.
10. ^{{cite journal|last1=Burdekin|first1=D.A.|last2=Rushforth|first2=K.D.|others=Revised by J.F. Webber|title=Elms resistant to Dutch elm disease|journal=Arboriculture Research Note|date=November 1996|volume=2/96|pages=1–9|url=https://www.trees.org.uk/kenticotrees/Trees.org.uk/files/90/90f2d2f6-3d77-459c-8288-d951b0bf9782.pdf|accessdate=26 October 2017|publisher=Arboricultural Advisory & Information Service|location=Alice Holt Lodge, Farnham|issn=1362-5128}}
11. ^Johnson, O. (2011). Champion Trees of Britain & Ireland, p. 169. Kew Publishing, Kew, London. {{ISBN|9781842464526}}.
12. ^{{cite web|title=List of plants in the {elm} collection|publisher=Brighton & Hove City Council|access-date=23 September 2016|url=http://www.brighton-hove.gov.uk/content/leisure-and-libraries/parks-and-green-spaces/list-plants-collection}}