- Ulmus 'Morton Stalwart'
-
Ulmus hybrid 
Commendation Elm [1]Details Hybrid parentage 'Morton' (Accolade) × (U. pumila × U. minor). Cultivar 'Morton Stalwart' = Commendation™ Origin USA The Elm tree Ulmus 'Morton Stalwart' (Commendation), is a Morton Arboretum hybrid from a controlled crossing of 'Morton' (Accolade) with a Ulmus pumila × U. minor (syn. carpinifolia) [2] from eastern Russia.[3]
Contents
Description
The 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 'Morton Glossy' (Triumph) and 'Morton Plainsman' (Vanguard), as 'ugly' by Michael Dirr, Professor of Horticulture at the University of Georgia [1], on account of its 'wild' growth and splaying branches.
Pests and diseases
Although resistant to Dutch elm disease, the tree is moderately susceptible to insects,[3] notably elm leaf beetle Xanthogaleruca luteola,[4] Japanese beetle [5] and Gypsy moth.
Cultivation
'Morton Stalwart' 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] it 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.
'Morton Stalwart' was introduced by Chicagoland Grows Inc.,[3] and is currently being evaluated in the National Elm Trial[8] coordinated by Colorado State University. The tree is not known to have been introduced to Europe or Australasia.
Accessions
- North America
- Arnold Arboretum. Acc. no. 131-2002
- Bickelhaupt Arboretum. Acc. no. 02-018
- Brenton Arboretum, Dallas Center, Iowa. 5 trees, acquired 2009. Acc. no. not known.
- Chicago Botanic Garden, Glencoe, Illinois. 1 tree, planted in the Parking Lots; no other details available.
- Dawes Arboretum [2], Newark, Ohio. 2 trees, no acc. details available.
- Holden Arboretum. Acc. no. 00-124
- Morton Arboretum. Acc. nos. 274-97, 109-2006.
- Smith College. Acc. no. 36405
- University of Idaho Arboretum. Two trees. Acc. no. 2000089
References
- ^ Cirrus Digital Commendation Elm
- ^ Cirrus Digital Hybrid Elm - Ulmus (carpinifolia x pumila)
- ^ a b c Morton Arboretum Commendation Elm
- ^ a b McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, pp 32-36.
- ^ 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, pp 15, 16. University of Kentucky.
- ^ Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota.
- ^ 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.
- ^ CSU Shade Tree Lab
Categories:- Elm cultivars
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