Ulmus americana 'Jefferson' explained

Ulmus americana 'Jefferson'
Species:Ulmus americana
Cultivar:'Jefferson'
Origin:National Park Service, US

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 ("The Castle") on the National Mall in Washington, D.C.[1] 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).[1]

In 2005, the Park Service and the Agricultural Research Service (ARS) of the United States Department of Agriculture jointly released the clone (formerly NPS 3–487) to the nursery trade as 'Jefferson'.[1] The parent tree appears to have remained unscathed by DED in 2014.

Description

'Jefferson' is distinguished by its low, spreading form with arching limbs and broad U-shaped crotches.[2] The parent tree on the National Mall has reached a height of about 68feet after 80 years. Ploidy: 2n = 42.

Genetics

Early studies on the parent tree found that the tree has triploid chromosomes, suggesting that it may be a hybrid between the tetraploid American Elm and an unknown diploid species.[3] A genetic study that the ARS conducted on the clone at the United States National Arboretum in Washington, D. C., during 2004 confirmed the tree as Ulmus americana, despite having some atypical features.[4]

A subsequent ARS study also confirmed that the tree is a triploid. The study's investigators concluded that a crossing of two American Elms, one a tetraploid, the other a less common diploid, had created the tree. The investigators found no triploids among the 81 wild trees that they sampled.[5]

Pests and diseases

The tree proved highly resistant to Dutch elm disease in an ARS trial (as clone N 3487/NA 62001).[6] NA 62001 showed little damage from elm leaf beetle (Xanthogaleruca luteola) feeding during a 2009—2010 survey at an Oklahoma arboretum.[7] 'Jefferson' is susceptible to elm yellows phytoplasma infection, as are other U. americana DED-resistant cultivars and native trees of that species.[8]

The Japanese beetle (Popillia japonica) highly prefers U. americana when feeding.[9] Verticillium wilt had a greater effect on U. americana than it had on all other elms studied in an investigation of that fungal disease.[10]

Cultivation

'Jefferson' has not been widely tested beyond Washington D.C. National Elm Trial results were inconclusive and provided no data on ‘Jefferson’ because of an early error in tree identification that occurred in the nursery trade.[11] [12] The error may still be causing nurseries to sell 'Princeton' elms that are mislabeled as 'Jefferson', although one can distinguish between the two cultivars as the trees mature.[11] [13] The Golden Hill Nursery in Kent introduced 'Jefferson' to the United Kingdom in 2010, but the clone remains rare in cultivation.

Accessions

North America

Europe

External links

References

Notes and References

  1. (1) Web site: Flores. Alberto. June 13, 2006. Jefferson Trees Resistant to Dutch Elm Disease. News & Events. United States Department of Agriculture

    Agricultural Research Service

    . January 30, 2021. In 2005, the newest American elm—named Jefferson—was released jointly by ARS and the National Park Service (NPS), after collaborative screening tests by Townsend and James L. Sherald, NPS Natural Resource Officer, showed it to have an outstanding level of Dutch elm disease (DED) tolerance. It was cloned in 1993 from the original tree, a survivor of about 300 elms planted on the National Mall in Southwest Washington in the 1930s.. January 26, 2021. https://web.archive.org/web/20210126191603/http://www.ars.usda.gov/news-events/news/research-news/2006/jefferson-trees-resistant-to-dutch-elm-disease/. dead. .
    (2) Web site: Bentz. S.E.. February 2005. Mature American elm of variety "Jefferson," at the old Smithsonian building, Washington, DC. photograph. elmpost.org elmpost.org]. January 30, 2021. February 2, 2017. https://web.archive.org/web/20170202204918/http://www.elmpost.org/2005-02.htm. dead. .
    (3) Sherald, 2009, pp. 37—38.
  2. https://www.nps.gov/nationalmallplan/Documents/Studies/ElmsoftheMonuCore_HistandMgmtPlan_122009.pdf Sherald, 2009, p. 38.
  3. (1) James L.. Sherald. Frank S.. Santamour Jr.. Ravindra K.. Hajela. Neerja. Hajela. Mariam B.. Sticklen. April 1, 1994. A Dutch elm disease resistant triploid elm. Canadian Journal of Forest Research. 24. 4. 647–653. 10.1139/x94-087. 1208-6037. 969764715. 71618428. Ottawa, Ontario. Canadian Science Publishing. January 30, 2021.
    (2) Web site: Warren. Keith. August 21, 2000. American Elm Cultivars - Ulmus americana: Ulmus americana 'Jefferson': Jefferson Elm. Return of the Elm: The Status of Elms in the Nursery Industry in 2000. J. Frank Schmidt & Son Co.. Triploid. May be a hybrid between tetraploid U. americana and an unknown diploid species.. https://web.archive.org/web/20030413074605/http://fletcher.ces.state.nc.us/programs/nursery/metria/metria11/warren/elm.htm. April 13, 2003. North Carolina State University

    Mountain Horticultural Crops Research and Extension Center

    .
  4. Pooler. Margaret R.. Townsend. A. M.. September 2005. Research Reports: DNA Fingerprinting of Clones and Hybrids of American Elm and Other Elm Species with AFLP Markers. Journal of Environmental Horticulture. 23. 3. 113–117. 10.24266/0738-2898-23.3.113. 0738-2898. 1057932522. 83643944. Washington, D.C.. Horticultural Research Institute (HRI), the AmericanHort Foundation. (Jefferson's) identity has been questioned due to its disease tolerance, broad U-shaped branch unions, and bark, branch, and leaf characteristics.. free. .
  5. (1) Web site: Kaplan. Kim. March 30, 2011. Hidden elm population may hold genes to combat Dutch elm disease. Research News. United States Department of Agriculture

    Agricultural Research Service

    . January 30, 2021. To settle the question, the two scientists tested elm trees from across the species' eastern and central U.S. range. About 21 percent of the wild elms sampled were diploid; some grew in stands with tetraploids, while others were larger groupings of diploids.. April 6, 2019. https://web.archive.org/web/20190406224246/https://www.ars.usda.gov/news-events/news/research-news/2011/hidden-elm-population-may-hold-genes-to-combat-dutch-elm-disease/. dead. .
    (2) Alan T.. Whittemore. Richard T.. Olsen. April 1, 2011. Ulmus americana (Ulmaceae) is a polyploid complex. American Journal of Botany. 98. 4. 754–760. 10.3732/ajb.1000372. 21613171. 0002-9122. 937099651. 41149435. 17005518. St. Louis. Botanical Society of America. January 30, 2021. The two ploidy levels grew in proximity to one another at several sites, east of the Appalachians and in eastern Missouri and west-central Oklahoma. Despite finding diploid and tetraploid trees growing near each other in several areas, no wild triploids were encountered..
  6. Townsend. A. M.. Bentz. S. E.. Douglass. L. W.. March 2005. Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease. Journal of Environmental Horticulture. 23. 1. 21–24. Washington, D.C.. Horticultural Research Institute (HRI), the AmericanHort Foundation. 10.24266/0738-2898-23.1.21. 0738-2898. 1057932522. 83643944. free. .
  7. Web site: Elm Leaf Beetle Survey. 17 July 2017. Clinton, Oklahoma. Sunshine Nursery & Arboretum. https://web.archive.org/web/20110719132152/http://www.sunshinenursery.com/survey.htm. July 19, 2011.
  8. (1) Sinclair. W. A.. Townsend. A..M.. Sherald. J. L.. May 2001. Elm Yellows Phytoplasma Lethal to Dutch Elm Disease-Resistant Ulmus americana Cultivars. Plant Disease. 85. 5. 560. St. Paul, Minnesota. American Phytopathological Society. Alexander V.. Karasev. 10.1094/PDIS.2001.85.5.560B. 30823144. 819181727. 79643690. 0191-2917. February 1, 2021. February 1, 2021. https://web.archive.org/web/20210201161515/https://pubmed.ncbi.nlm.nih.gov/30823144/. dead. .
    (2) Web site: Elm yellows (Candidatus Phytoplasma ulmi). Forest Research. 2020. England. Forestry Commission. Infection can be very destructive to some elms, particularly North American species. However, it is thought that European elm species tend to be much less affected than the highly susceptible American elm (U. americana).. February 1, 2021. December 2, 2020. https://web.archive.org/web/20201202094409/https://www.forestresearch.gov.uk/tools-and-resources/pest-and-disease-resources/elm-yellows-candidatus-phytoplasma-ulmi/. dead. .
  9. Miller. Fredric. Ware. George. Jackson. Jennifer. 2001-04-01. Preference of Temperate Chinese Elms (Ulmus spp.) for the Adult Japanese Beetle (Coleoptera: Scarabaeidae). Journal of Economic Entomology. Oxford University Press (OUP). 94. 2. 445–448. 0022-0493. 1131914636. 10.1603/0022-0493-94.2.445. 11332837. 7520439. 11008063. free.
  10. Book: Pegg. G. F.. Brady. B. L.. 2002. Verticillium Wilts. 290478616. 291. 2001037313. 0-85199-529-2. Wallingford, Oxon, UK. CABI Publishing. Google Books.
  11. Tom. Zetterstrom. Pinchot. Cornelia C.. Knight. Kathleen S.. Haugen. Linda M.. Flower. Charles E.. Slavicek. James M.. 2017. Report From the Street. Proceedings of the American Elm Restoration Workshop 2016; 2016 October 25–27; Lewis Center, OH. Newtown Square, PA. 119–121. 1231892730. 10.2737/NRS-GTR-P-174. United States Department of Agriculture, United States Forest Service, Northern Research Station. Gen. Tech. Rep. NRS-P-174. February 7, 2021. Consumers need to also be aware that a nursery trade mix-up a dozen years ago still plays out in the marketplace, and ‘Princeton’ elms continue to be sold as ‘Jefferson’ unknowingly by reputable nurseries from New York to Minnesota. .... National Elm Trial (NET) results were inconclusive and provided no data on ‘Jefferson’ due to the cultivar mix-up.. free. May 1, 2019. https://web.archive.org/web/20190501223229/https://www.fs.fed.us/nrs/pubs/gtr/gtr-nrs-p-174papers/13zetterstrom-gtr-p-174.pdf. dead. .
  12. Jason J.. Griffin. William R.. Jacobi, E.. Gregory. McPherson. Clifford S.. Sadof. James R.. McKenna. Mark L.. Gleason. Nicole Ward. Gauthier. Daniel A.. Potter. David R.. Smitley. Gerard C.. Adams. Ann Brooks. Gould. Christian R.. Cash. James A.. Walla. Mark C.. Starrett. Gary. Chastagner. Jeff L.. Sibley. Vera A.. Krischik. Adam F.. Newby. 4. Ten-Year Performance of the United States National Elm Trial. 2017. Arboriculture & Urban Forestry. 43. 3. 107–120. 10.17660/ActaHortic.2018.1191.5. 7347020445. 0567-7572. International Society of Arboriculture. February 7, 2021.
  13. Web site: Jefferson American Elm vs. Princeton American Elm. Disease-Resistant Elm Identification Guide. University of Minnesota

    Urban Forestry Outreach, Research & Extension: The UFore Nursery & Lab

    . February 7, 2021. February 7, 2021. https://web.archive.org/web/20210207235201/https://trees.umn.edu/elmid. dead. .

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