The American Elm

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...

''Ulmus americana'' 'Delaware' was originally selected (as tree number 218, a c.1940 seedling from North Dakota) from 35,000 seedlings inoculated with the

Dutch elm disease Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into Americas, America ...

fungus in

USDA The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...

trials at Morristown,

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

Description

The tree has a relatively low stature and "undesirable" branching habit.Townsend, A. M., Bentz, S. E., and Douglass L. W. (2005)
Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease
''Journal of Environmental Horticulture'', March 2005, Horticultural Research Institute, Washington, D.C.

Pests and diseases

Further disease-resistance trials were conducted by both the USDA and the United States National Arboretum which confirmed the clone had a fair level of resistance to Dutch elm disease. 'Delaware' is susceptible to

Elm Yellows Elm yellows is a plant disease of elm trees that is spread by leafhoppers or by root grafts."Elm Yellows." Elmcare.Com. 19 Mar. 2008 . Elm yellows, also known as elm phloem necrosis, is very aggressive, with no known cure. Elm yellows occurs in the ...

, but resistant to the Elm Leaf Beetle '' Xanthogaleruca luteola''.

Cultivation

The original tree, which had been moved to the

National Arboretum,

Washington, D. C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, Na ...

in 1948, died from unknown causes (probably elm yellows, by some accounts) in 1980, but a clone survives at the Denver Botanic Gardens, as 'Delaware II'. Seven specimens stand in the

National Mall The National Mall is a Landscape architecture, landscaped park near the Downtown, Washington, D.C., downtown area of Washington, D.C., the capital city of the United States. It contains and borders a number of museums of the Smithsonian Institut ...

area, Washington D.C. Pruned 'Delaware', National Museum of Natural History, Constitution Avenue NW, Washington DC - Google Maps, August 2022, access date: 17 October 2022
/ref> Although propagated for further trials, the tree was never commercially released owing to its poor shape. 'Delaware' is not known to have been introduced to

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologica ...

. File:Washington Road Elm Allée (east side).jpg, Mature 'Princeton' elms on right, planted 1920s; 'Delaware' on left, planted in 1983, in a side allée of the Washington Road Elm Allée, Princeton, New Jersey, US (2011)

Synonymy

*'Delaware II'. NB 'Delaware I' is the original name given to the hybrid 'Urban' before its commercial release.

Accessions

North America

*Brooklyn Botanic Garden">Ulmus 'Urban'">'Urban' before its commercial release.

Accessions

North America

*Brooklyn Botanic Garden

New York City, New York, US. Acc. no. 980489. *Dawes Arboretum, US

Newark, Ohio, Newark,

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

, US. 1 tree, listed as 'Delaware #2'; no acc. details available. * Denver Botanic Gardens, US. No details available. *

Dominion Arboretum The Dominion Arboretum (french: Arboretum du Dominion) is an arboretum part of the Central Experimental Farm of Agriculture and Agri-Food Canada in Ottawa, Ontario, Canada. Originally begun in 1889, the Arboretum covers about of rolling land ...

, Canada

No details available.

References

{{DEFAULTSORT:Ulmus Americana 'Delaware' American elm cultivar Ulmus articles with images Ulmus