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{{SPlantbox
{{SPlantbox
|familia=Ulmaceae
|familia=Ulmaceae
|genus=Ulmus
|genus=Ulmus
|species='Sapporo Autumn Gold'
|species='Sapporo Autumn Gold'
|habit=tree
|Max ht box=50
|Max ht box=50
|Max ht metric=ft
|Max ht metric=ft
|Max wd metric=ft
|Max wd metric=ft
|width_ref=Flora - A Gardener's Encyclopedia
|width_ref=Flora - A Gardener's Encyclopedia
|lifespan=perennial
|exposure=sun
|exposure=sun
|sun_ref=Flora - A Gardener's Encyclopedia
|sun_ref=Flora - A Gardener's Encyclopedia
|usda_ref=Flora - A Gardener's Encyclopedia
|usda_ref=Flora - A Gardener's Encyclopedia
|max_zone=9
|max_zone=9
|image=Upload.png
|image=Sapporo Autumn Gold 2.jpg
|image_width=240
|image_width=180
}}
}}
''''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 <ref name=Santamour>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.</ref>. 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 [[Eugene Byron Smalley|Prof. Eugene Smalley]] and patented in 1975 <ref name=Smalley,a>Smalley, E. B. & Lester, D. T. (1973). ''HortScience'' 8: 514-515, 1973.</ref> <ref name=Smalley,b>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.</ref>.
The tree forms a densely foliated vase-shaped crown, although immature plants produce vigorous side shoots that require assiduous pruning to develop the desired shape. The leaves are narrowly-[[leaf shape|elliptical]], < 8.5 cm long by < 4.0 cm wide and, as the name implies, turn pale yellow in autumn. The [[perfect flower|perfect]], [[apetalous]] wind-pollinated flowers appear in March, followed by the seeds in April; flowering usually begins when the tree is aged six years.
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]] [http://www.for.nau.edu/cms/content/view/512/706/] found that it is not very tolerant of a hot, arid environment although its leaves sustain comparatively little scorch damage. Moreover, in trials in southern [[England]] conducted by ''[[Butterfly Conservation]]'' the tree was found to be intolerant of ponding over winter.
==Cultivation==
==Cultivation==
===Pests and diseases===
===Pests and diseases===
'Sapporo Autumn Gold' possesses a very high resistance to [[Dutch elm disease]] <ref name Pinon,b>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.</ref> <ref name=Pinon>Pinon, J. (2007). Les ormes résistants à la graphiose. ''Forêt-entreprise'', No. 175 - Juillet 2007, p 37-41, France.</ref> and a tolerance of [[Verticillium]] wilt <ref name=Burdekin> 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.</ref>. The tree's foliage was adjudged "resistant" to [[Black Spot (disease)|Black Spot]] by the Plant Diagnostic Clinic of the [[University of Missouri]] [http://soilplantlab.missouri.edu/plant/diseases/resistant.htm], however it can be severely damaged the Elm Leaf Beetle ''[[Xanthogaleruca luteola]]'' in the [[USA]] [http://www.sunshinenursery.com/survey.htm]
==Varieties==
==Varieties==