Ulmus americana 'Princeton'
Mature Princeton Elms on the right, planted in the 1920s, with Delaware Elms planted in 1983 on the left. One of the side allées of the Washington Road Elm Allée in Princeton, New Jersey, United States.
SpeciesUlmus americana
Cultivar'Princeton'
Marketing namesPrinceton American Elm
OriginPrinceton Nurseries

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).[1][2][3]

Description

American elm is a vase-shaped, medium to large, deciduous tree.[4] The tree can grow to greater than 30 m in height, and is distinguished by its dense, symmetrical, upright form and dark green foliage, ultimately forming a broad umbrella crown. Crotch angles can be acute, with considerable bark inclusion which can later lead to branch breakages. The leaves are less than 16 cm long by 8 cm broad. 'Princeton' grows quickly, young trees increasing in height by over 1.6 m per annum (d.b.h. by 2.8 cm p.a.) in an assessment at U C Davis as part of the National Elm Trial.[5] The tree commences flowering aged nine years.

Pests and diseases

Testing in laboratory conditions by the United States Department of Agriculture (USDA) from 1992 to 1993 revealed that 'Princeton' had some resistance to Dutch elm disease (DED),[6][7][8] although the original Princeton elm, which grew in Princeton Cemetery and was estimated to be over 150 years old, was felled in April 2005 after suffering 60 percent dieback, attributed by some accounts to Dutch Elm Disease.[9] A 2016 publication later reported that, of 100 Princeton elms planted from 2001 to 2007 within a three state area in the United States, nine came down with DED, seven died, and two were saved by assiduous pruning.[2]

Moreover, trees introduced to the United Kingdom, where the larger bark beetle Scolytus scolytus is the principal vector, were found to be susceptible, and many died, as did all 20 sent to Eisele, Darmstadt, for testing by inoculation with the pathogen.[10] Princeton elms planted in North America are highly prone to leaf damage by Japanese beetles Popillia japonica.[11] Trees grown in the UK have also proven very susceptible to damage by leaf-feeding insects, far more so than native or Asiatic elms. Henry noted that such damage was common to all American Elm Ulmus americana grown in the UK.[12] Trees grown in northern California at UC Davis became infested with leaf curling aphids (Eriosoma), producing copious amounts of honeydew.[5]

Regular pruning and spraying is advisable because of Dutch elm disease.[4] The preferred cultivars of the American elm (Ulmus americana) for resistance to DED are 'New Harmony' and 'Princeton' as determined by the National (American) Elm Trial.[5][13]

Cultivation

Princeton Elm, Rugby School, Warwickshire, England.[14]

It can be grown in USDA zones 4 through 9,[4] in "...average, medium moisture, well-drained soils in full sun. [It is t]olerant of light shade [and p]refers rich, moist loams [adapting] to both wet and dry sites. [It is g]enerally tolerant of urban conditions."[4]

Examples of 'Princeton' were planted along Washington Road and another road in Princeton; most of these trees survive to this day unaffected by disease.[15] In 2005, approximately 90 Princeton elms were planted along Pennsylvania Avenue in front of the White House in Washington, D.C.[16] 'Princeton' is currently being evaluated in the United States as part of the National Elm Trial coordinated by Colorado State University.[17]

The tree was introduced to the UK by Penelope Hobhouse, who obtained two specimens from the New York Botanical Gardens for planting at her family home, Hadspen, in Somerset. The tree was later marketed by the Knoll Gardens nursery in Dorset. In 2005, 50 'Princeton' were planted by The Prince of Wales to create the Anniversary Avenue at his residence Highgrove House, however all the trees were removed and burnt in 2012 after five died of DED.[10] In Ireland, 100 were planted in Phoenix Park, Dublin, in 2009 to replace some of the 2000 native elms lost to Dutch elm disease since the 1980s.[18] In Scotland, some six have been planted in Edinburgh parks (Gayfield Square Park, The Meadows, Leith Links).[19]

Accessions

Row of Princeton elm trees at Scripps College in Claremont, California

North America

Europe

Nurseries

North America

References

  1. ↑ (1) "Ulmus americana 'Princeton'". Missouri Botanical Garden.
  2. 1 2 Zetterstrom, Tom. "Report From The Street: Elm Reintroduction" (PDF). Proceedings of the American elm restoration workshop 2016. United States Forest Service. pp. 119–121. Archived from the original (PDF) on 2019-05-01. Retrieved 2019-04-28.
  3. ↑ "Taking another look at American elm trees". www.ksre.k-state.edu. Retrieved 2023-10-12.
  4. 1 2 3 4 "Princeton American Elm | The UFOR Nursery & Lab". trees.umn.edu. Retrieved 2023-10-12.
  5. 1 2 3 McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, pp. 32–36.
  6. ↑ Santamour, J., Frank, S. & Bentz, S. (1995). Updated checklist of elm (Ulmus) cultivars for use in North America. Journal of Arboriculture, 21:3 (May 1995), pp. 121–131. International Society of Arboriculture, Champaign, Illinois, USA.
  7. ↑ Smalley, E. B. & Guries, R. P. (1993). Breeding Elms for Resistance to Dutch Elm Disease. Annual Review of Phytopathology Vol. 31: 325–354. Palo Alto, California.
  8. ↑ 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.
  9. ↑ Hansel, John P. "Princeton Elm lamented" (PDF). Elm Leaves (2005 Summer): 1. Archived from the original on 2007-02-21.{{cite journal}}: CS1 maint: bot: original URL status unknown (link)
  10. 1 2 Brookes, A. H. (2017). Great Fontley Elm Trial, 2017 Report. Butterfly Conservation, Lulworth, England.
  11. ↑ 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.
  12. ↑ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. 1848–1929. Private publication. Archived 2008-10-05 at the Wayback Machine
  13. ↑ Griffin, J. J.; Jacobi, W. "Ten-year performance of elms in the National Elm Trial". www.actahort.org. doi:10.17660/ActaHortic.2018.1191.5. Retrieved 2023-10-12.
  14. ↑ Information from Rugby School, 2017
  15. ↑ "Princeton Elm Picture Gallery". Botany Shop. 14 December 2009. Archived from the original on 31 March 2016. Retrieved 2017-07-13.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  16. ↑ (1) "Elm, Princeton – Ulmus americana 'Princeton'". South Chatsworth, Georgia: Native Forest Nursery. 2016. Archived from the original on 2019-05-01. Retrieved 2019-04-28.
    (2) Sanders, Jessica R.; Woodworth Jr., James W. (2013-11-25). "Proactive, Not Reactive: Evolving Elm Management in the Nation's Capital". Cities and the Environment (CATE). 6 (1, article 8). Archived from the original on 2019-05-01. Retrieved 2019-04-28 – via Digital Commons @ LMU and LLS.
    (3) Sherald, James L. (December 2009). Elms for the Monumental Core: History and Management Plan (PDF). Washington, D.C.: Center for Urban Ecology, National Capital Region, National Park Service. p. 39. Natural Resource Report NPS/NCR/NRR--2009/001. Archived from the original (PDF) on 2010-11-29. Retrieved 2010-10-14.
  17. ↑ "National Elm Trial". Colorado State University. 21 November 2008. Archived from the original on 21 July 2011. Retrieved 2017-07-13.
  18. ↑ Appleby, Matthew (10 February 2009). "Disease-tolerant elms thrive in UK". Horticulture Week. Retrieved 13 July 2017.
  19. ↑ Young 'Princeton', Gayfield Square Gardens – Google Maps, August 2020, access date: 20 October 2022
  20. ↑ "List of plants in the {elm} collection". Brighton & Hove City Council. Retrieved 23 September 2016.
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