Ulmus 'Morton Plainsman' Vanguard

Ulmus hybrid cultivar
Hybrid parentage U. pumila × U. davidiana var. japonica
Cultivar 'Morton Plainsman' = Vanguard™
Origin USA

Ulmus 'Morton Plainsman' (selling name Vanguard™) is a hybrid cultivar raised by the Morton Arboretum from a crossing of Siberian Elm (female parent) and a Japanese Elm grown from openly-pollinated seed donated by the Agriculture Canada Research Station at Morden, Manitoba.

Description

Vanguard has modest upright growth, increasing in height by an average of 0.8 m in an assessment at U C Davis,[1] with leaves much the same size and colour of the American Elm. However, its performance in the southern United States has not impressed, and it was dismissed, along with its Morton stablemates Commendation and Triumph, as "ugly" by Michael Dirr, Professor of Horticulture at the University of Georgia , on account of its "wild" growth and splaying branches.

Pests and diseases

Although resistant to Dutch elm disease, Vanguard remains very susceptible to pests such as the elm-leaf beetle Xanthogaleruca luteola [1] , Japanese beetle,[2] and cankerworms.

Cultivation

In trials at the University of Minnesota, Vanguard was found to have the second highest (after Danada Charm) incidence of branch breakage occasioned by bark inclusions.[3] However, the tree has a high degree of drought and cold tolerance making it particularly suitable for afforestation in the Great Plains.[4][5] In artificial freezing tests at the Morton Arboretum [6] the LT50 (temp. at which 50% of tissues die) was found to be -40°C.

The tree is currently being evaluated in the National Elm Trial coordinated by Colorado State University. It is not known to have been introduced to Australasia.

Hybrid cultivars

Vanguard was crossed with the hybrid cultivar Accolade. A selection of the resultant seedlings was marketed under the name 'Charisma', later changed to 'Morton Glossy' = Triumph.

Accessions

North America
Europe

Nurseries

North America

References

  1. 1 2 McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, 32–36.
  2. ↑ 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.
  3. ↑ Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota.
  4. ↑ Santamour, Frank S.; Bentz, Susan E. (May 1995). "Updated Checklist of Elm (Ulmus) Cultivars for use in North America". Journal of Arboriculture. 21 (3): 122–131. Retrieved 20 June 2016.
  5. ↑ Ware, G. (1992). Morton. Arb. Quarterly 28(1): 1–5, 1992.
  6. ↑ 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.
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