| 词条 | Ulmus 'Morton Stalwart' = Commendation |
| 释义 |
| name = Ulmus 'Morton Stalwart' | hybrid = {{tdes|Accolade|caps}} × (U. minor × U. pumila) | genus = Ulmus | cultivar = 'Morton Stalwart' = {{tdes|Commendation|caps}}™ | image= Ulmus morton stalwart-commendation elm.JPG | image_caption = {{tdes|Commendation|caps}}, 14 years old.[1] | origin = US }}Ulmus 'Morton Stalwart' (selling name {{tdes|Commendation|caps}}™), is a Morton Arboretum hybrid cultivar arising from a controlled crossing of {{tdes|Accolade|caps}} with the hybrid of a Field Elm U. minor from eastern Russia and a Siberian Elm U. pumila. [2] [3] DescriptionThe branches are upright, but the form of the tree is more oval than vase-shaped; the leaves are relatively large. However, examples grown in the warmer climes of the southern United States have not impressed, and it was dismissed, along with its Morton stablemates {{tdes|Triumph|caps}} and {{tdes|Vanguard|caps}}, as 'ugly' by Michael Dirr, Professor of Horticulture at the University of Georgia , on account of its 'wild' growth and splaying branches. Pests and diseasesAlthough resistant to Dutch elm disease in the USA, the tree is moderately susceptible to insects,[3] notably elm leaf beetle Xanthogaleruca luteola,[4] Japanese beetle [5] and Gypsy moth. Cultivation{{tdes|Commendation|caps}} is vigorous and robust, adjudged the third fastest-growing cultivar of 17 assessed by the University of Minnesota and fourth out of 15 in trials at U C Davis.[4] The tree is also extremely tolerant of drought [6] and cold; in artificial freezing tests at the Morton Arboretum [7] the tree was found cold-hardy to -40 °C.{{tdes|Commendation|caps}} was introduced by Chicagoland Grows [3] and is currently being evaluated in the National Elm Trial[8] coordinated by Colorado State University. The tree was introduced to the UK in 2014, but is not known (2016) to have been introduced to Australasia.Accessions
References1. ^Cirrus Digital Commendation Elm {{Elm species, varieties, hybrids, hybrid cultivars and species cultivars |state=collapsed}}{{DEFAULTSORT:Ulmus 'Morton Stalwart' Commendation}}2. ^Cirrus Digital Hybrid Elm - Ulmus (carpinifolia x pumila) 3. ^1 2 Morton Arboretum Commendation Elm 4. ^1 McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, 32–36. 5. ^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. 6. ^Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota. 7. ^Shirazi, A. M. & Ware, G. H. (2004). Evaluation of New Elms from China for Cold Hardiness in Northern Latitudes. International Symposium on Asian Plant Diversity & Systematics 2004, Sakura, Japan. 8. ^CSU Shade Tree Lab {{Webarchive|url=https://web.archive.org/web/20080226012323/http://treehealth.agsci.colostate.edu/research/nationalelmtrial/NET_Cultivars.htm |date=2008-02-26 }} 3 : Hybrid elm cultivar|Ulmus articles with images|Ulmus |
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