Ulmus americana 'American Liberty'

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Ulmus americana 'American Liberty'
WWII Submarine Veterans Memorial San Diego Dec 2015.jpg
'Liberty' elms, WWII Submarine Veterans Memorial, San Diego (2015)
Species Ulmus americana
Cultivar 'American Liberty'
OriginERI, US

The American elm cultivar Ulmus americana 'American Liberty' is in fact a group of six genetically distinct cultivars under a single name, although they are superficially similar. [1] The Liberty elm is reportedly suitable for street planting, being tolerant of de-icing salts and air pollution. However, examples included in 10-year trials at Atherton, California to evaluate replacements for Californian elms lost to disease did not perform well. The late Professor Eugene Smalley summarized 'American Liberty' as "not as resistant as the Asian hybrids, but it still has the look of a classic American Elm". [2]

Contents

Description

Generally similar to the species.[ citation needed ]

Pests and diseases

The six clones which comprise this series vary considerably in their level of resistance to Dutch elm disease, and none is immune, but some evidence suggests that at least one of the six clones may have a fairly high degree of DED-resistance. [3] It is claimed, controversially, by ERI that fewer than 180 American Liberty elm trees have been known to succumb to DED since the planting began in the early 1980s. This figure is surprising in the light of Townsend & Douglass's work, [4] which found that the Liberty elms exhibited only an 18% survival rate four years after inoculation, compared with 96% for both 'Valley Forge' and 'Princeton', and 100% for the Japanese elm clone 'Prospector'.

The 'American Liberty' elms also sustained wind damage in winter, and high levels of injury from the elm leaf beetle Xanthogaleruca luteola . Accordingly, the cultivar was deemed "highly questionable as a replacement". [5] Moreover, the trees were noted as highly susceptible to elm yellows in New York. [6] Examples tested by research scientists at the United States National Arboretum in the 1992-1993 also failed to perform well ; but unfortunately, it has never been clear which of the six clones were represented in the tests, so the results remain largely inconclusive.

Cultivation

Promoted exclusively by the Elm Research Institute (ERI) since 1983, these trees have been planted across the United States in numbers the organization claims to be in excess of 250,000. The American Liberty elm is reputedly "extremely expensive" to buy, particularly in the larger sizes. [7] The tree is not known to have been introduced to Europe or Australasia.

Accessions

North America

Related Research Articles

<i>Ulmus americana</i> Species of tree

Ulmus americana, generally known as the American elm or, less commonly, as the white elm or water elm, is a species of elm native to eastern North America, naturally occurring from Nova Scotia west to Alberta and Montana, and south to Florida and central Texas, and is the State Tree of Massachusetts. The American elm is an extremely hardy tree that can withstand winter temperatures as low as −42 °C. Trees in areas unaffected by Dutch elm disease (DED) can live for several hundred years. A prime example of the species was the Sauble Elm, which grew beside the banks of the Sauble River in Ontario, Canada, to a height of 43 m (140 ft), with a d.b.h of 196 cm (6.43 ft) before succumbing to DED; when it was felled in 1968, a tree-ring count established that it had germinated in 1701.

<i>Ulmus</i> Frontier Elm cultivar

Ulmus 'Frontier' is an American hybrid cultivar, a United States National Arboretum introduction derived from a crossing of the European Field Elm Ulmus minor with the Chinese Elm Ulmus parvifolia in 1971. Released in 1990, the tree is a rare example of the hybridization of spring- and autumn-flowering elms. Tested in the US National Elm Trial coordinated by Colorado State University, 'Frontier' averaged a survival rate of 74% after 10 years.

<i>Ulmus</i> Homestead Elm cultivar

Ulmus 'Homestead' is an American hybrid elm cultivar raised by Alden Townsend of the United States National Arboretum at the Nursery Crops Laboratory in Delaware, Ohio. The cultivar arose from a 1970 crossing of the Siberian Elm Ulmus pumila with the hybrid N 215, the latter grown from seed sent in 1960 to the University of Wisconsin-Madison elm breeding team by Hans Heybroek of the De Dorschkamp Research Institute in the Netherlands. Tested in the US National Elm Trial coordinated by Colorado State University, 'Homestead' averaged a survival rate of 85% after 10 years. 'Homestead' was released to commerce without patent restrictions in 1984.

<i>Ulmus</i> × <i>hollandica</i> Pioneer Elm cultivar

The hybrid elm cultivar Ulmus × hollandica 'Pioneer' is an American clone arising from the crossing of two European species, Wych Elm U. glabra and Field Elm U. minor. Raised by the USDA station at Delaware, Ohio, in 1971, 'Pioneer' was released to commerce in 1983.

<i>Ulmus</i> Morton Elm cultivar

Ulmus 'Morton' is an elm cultivar cloned from a putative intraspecific hybrid planted at the Morton Arboretum in 1924, which itself originated as seed collected from a tree at the Arnold Arboretum in Massachusetts. Although this tree was originally identified as Ulmus crassifolia, it is now believed to have been a hybrid of the Japanese elm and Wilson's elm. Accolade has proven to be the most successful cultivar tested in the US National Elm Trial, averaging a survival rate of 92.5% overall.

Ulmus 'Morton Plainsman' is a hybrid cultivar raised by the Morton Arboretum from a crossing of Siberian Elm and a Japanese Elm grown from openly pollinated seed donated by the Agriculture Canada Research Station at Morden, Manitoba. Tested in the US National Elm Trial coordinated by Colorado State University, Vanguard averaged a survival rate of 78% after 10 years.

<i>Ulmus minor</i> Christine Buisman Cultivar, resistant to Dutch elm disease

The Field Elm cultivar Ulmus minor 'Christine Buisman' was the first cultivar released by the Dutch elm breeding programme, initiated in response to the less virulent form of Dutch elm disease (DED), Ophiostoma ulmi, which afflicted Europe's elms after the First World War. 'Christine Buisman' was selected from a batch of 390 seedlings grown from seed collected in the Parque de la Quinta de la Fuente del Berro, Madrid, by Mrs Van Eeghen, a friend of elm researcher Johanna Westerdijk, in 1929 and named for the elm disease researcher Christine Buisman. Originally identified as Ulmus foliacea, it was later treated as Ulmus × hollandica by Melville. However, more recent research in Belgium using DNA markers has reaffirmed 'Christine Buisman' as a clone of U. minor.

<i>Ulmus americana</i> Princeton American elm cultivar

The American Elm cultivar Ulmus americana 'Princeton' was originally selected in 1922 by New Jersey nurseryman William Flemer of Princeton Nurseries for its aesthetic merit. 'Princeton' was later found to have a moderate resistance to Dutch elm disease (DED).

<i>Ulmus americana</i> Augustine Elm cultivar

The American elm cultivar Ulmus americana 'Augustine', originally called 'Augustine Ascending', was cloned by Archie M. Augustine of the Augustine Nursery of Bloomington, Illinois, from a nursery seedling planted in 1927 in Normal, Illinois, and found to be columnar in habit.

<i>Ulmus americana</i> Delaware Elm cultivar

The American Elm cultivar Ulmus americana 'Delaware' was originally selected from 35,000 seedlings inoculated with the Dutch elm disease fungus in USDA trials at Morristown, New Jersey.

<i>Ulmus americana</i> Valley Forge Elm cultivar

The American Elm cultivar Ulmus americana 'Valley Forge' was raised by the Agricultural Research Service in Maryland. The tree was released to wholesale nurseries without patent restrictions by the U. S. National Arboretum in 1995 after proving to have a high resistance to Dutch elm disease. 'Valley Forge' proved only moderately successful in the US National Elm Trial, averaging a survival rate of 66.7% overall, owing largely to environmental factors rather than susceptibility to disease.

<i>Ulmus americana</i> New Harmony Elm cultivar

The American elm cultivar Ulmus americana 'New Harmony' was raised by the Maryland Agricultural Research Service and released by the United States National Arboretum in 1995, along with 'Valley Forge'. 'New Harmony' proved the most successful U. americana cultivar in the US National Elm Trial, averaging a survival rate of 85.5% overall.

<i>Ulmus americana</i> Jefferson Elm cultivar

The American Elm cultivar Ulmus americana 'Jefferson' was cloned from a tree growing near a path in front of the Freer Gallery of Art, close to the Smithsonian Institution Building on the National Mall in Washington, D.C. The United States National Park Service, which had planted the tree during the 1930s, cloned it in 1993 after screening tests showed that it possessed an outstanding level of tolerance to Dutch elm disease (DED).

<i>Ulmus americana</i> Lewis & Clark Elm cultivar

The American elm cultivar Ulmus americana 'Lewis & Clark' is a development from the North Dakota State University (NDSU) Research Foundation breeding programme, released in 2004 to commemorate the 200th anniversary of the eponymous expedition. The cultivar was cloned from a tree discovered in 1994 along the Wild Rice River south west of Fargo, North Dakota, where all those around it had succumbed to Dutch elm disease; the tree remains in perfect health (2008). Prairie Expedition proved only moderately successful in the US National Elm Trial, averaging a survival rate of 62.6% overall, potentially due to environmental factors rather than susceptibility to Dutch elm disease.

<i>Ulmus davidiana</i> var. <i>japonica</i> Prospector Elm cultivar

The Japanese elm cultivar Ulmus davidianavar.japonica 'Prospector' was originally treated as a cultivar of Wilson's elm U. wilsonianaSchneid., a species sunk as Ulmus davidiana var. japonica by Fu. A U.S. National Arboretum introduction, it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio, and released without patent restrictions in 1990. 'Prospector' proved moderately successful in the US National Elm Trial, averaging a survival rate of 76% overall.

<i>Ulmus</i> Patriot Elm cultivar

Ulmus 'Patriot' is a hybrid cultivar raised by the United States National Arboretum in 1980. Derived from a crossing of the American hybrid 'Urban' with the Wilson's Elm cultivar 'Prospector', 'Patriot' was released to commerce, free of patent restrictions, in 1993. Tested in the US National Elm Trial coordinated by Colorado State University, 'Patriot' averaged a survival rate of 85% after 10 years.

<i>Ulmus</i> Fiorente Elm cultivar

Ulmus 'Fiorente' is a hybrid cultivar elm derived from a crossing of the Siberian Elm Ulmus pumila clone 'S.10' from Lucca, Italy, with the Ulmus minor clone 'C.02' from Lungarno, Florence, by the Istituto per la Protezione delle Piante (IPP), part of the Italian National Research Council, in Florence. The tree is protected by Plant Breeders' Rights bestowed by the EU on 25 March 2010.

The American Elm cultivar Ulmus americana 'Jackson' was cloned c.1990 from an elm selected at Wichita, Kansas, which had reputedly shewn no signs of Dutch elm disease damage at over 50 years of age.

The American Elm cultivar Ulmus americana 'Deadfree' was listed by the Urban Forestry Administration (UFA) of the District Department of Transportation in Washington, D.C., as one of its "street trees" in 2008. However, the UFA currently has no documentation to support it, and thus the entry may be spurious.

'Maine' is a selection of the American Elm Ulmus americana made by the USNA for use in disease-resistance trials. It has not been formally registered as a cultivar.

References

  1. ↑ Townsend, A. M., Bentz, S. E., and Douglass L. W. (2005). Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease Archived 2005-05-11 at the Wayback Machine .Journal of Environmental Horticulture, March 2005, Horticultural Research Institute, Washington, D.C.
  2. ↑ "New Varieties of Elm Raise Hope of Rebirth For Davastated Tree". The New York Times . December 5, 1989.
  3. ↑ Footnote About the Liberty Elms
  4. ↑ Townsend A. M. & Douglass, L. W. (2001). Variation among American Elm Clones in Long-term Dieback, Survival, and Growth Response to Ophiostoma Inoculation. Journal of Environmental Horticulture, June 2001. 150-154., Horticultural Research Institute, Washington, D.C.
  5. ↑ Costello, L. R. (2004). A 10 -year evaluation of the performance of four elm cultivars in California, U. S. Journal of Arboriculture, March 2004.
  6. ↑ Sinclair, W. A., Griffiths, H. G., & Lee, I-M., Journal of Arboriculture. 20: 176-189, 1994
  7. ↑ Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota.
  8. ↑ U. americana 'Liberty', Mount Holyoke College, Acc. no. E00330-1 mtholyoke.edu
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