Ulmus Americana 'Princeton'

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).

Description

American elm is a vase-shaped, medium to large, deciduous tree. 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.McPherson, G. ''et al''. (2008). National elm trial: Initial report from Northern California. ''Western Arborist'', Fall 2009, pp. 32–36. The tree commences flowering aged nine years.

Image: Princeton leaf.JPG, 'Princeton' leaf
Image:Princeton Elm foliage damage.jpg, Typical foliage damage sustained in England
Image:Princeton, bark inclusion.jpg, Crotch with bark inclusion

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),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.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.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. 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. 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.

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.Brookes, A. H. (2017). ''Great Fontley Elm Trial, 2017 Report''. Butterfly Conservation, Lulworth, England. Princeton elms planted in North America are highly prone to leaf damage by Japanese beetles ''Popillia japonica''.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. 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.Elwes, H. J. & Henry, A. (1913). ''The Trees of Great Britain & Ireland''. Vol. VII. 1848–1929. Private publication

Trees grown in northern California at UC Davis became infested with leaf curling aphids ('' Eriosoma''), producing copious amounts of honeydew.

Regular pruning and spraying is advisable because of Dutch elm disease. 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.

Cultivation

It can be grown in USDA zones 4 through 9, in "...average, medium moisture, well-drained soils in full sun. t is tlerant of light shade nd pefers rich, moist loams daptingto both wet and dry sites. t is gnerally tolerant of urban conditions."

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

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. 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. In Scotland, some six have been planted in Edinburgh parks (Gayfield Square Park, The Meadows, Leith Links).Young 'Princeton', Gayfield Square Gardens – Google Maps, August 2020, access date: 20 October 2022
/ref>

Accessions

North America

*Arnold Arboretum, US. Acc. nos. 352-91, 561-89.
*Bartlett Tree Experts, US. Acc. nos. 2001-249, 2001-250, 2001-251, 2001-484, 2001-485, 2003-964.
*Brentwood, Pennsylvania Arboretum, US. 11 specimens planted as street trees along educational campus, no acc. details available.
*Dawes Arboretum

Newark, Ohio, US. 2 trees, no acc. details available.
*Holden Arboretum, US. Acc. nos. 2002-435, 2003-174, 56-908.
*Longwood Gardens, US. Acc. nos. 2000-0362, 2002-0414, 2003-0032, 2004-0675.
*Morton Arboretum, US. Acc. no. 125-2008.
* U S National Arboretumbr>
Washington, D.C., US. Acc. no. 57842

Europe

*Brighton & Hove City Council, UK. NCCPG Elm Collection.
*Grange Farm Arboretum, Sutton St. James, Spalding, Lincs. UK. Acc. no. 697.
*Royal Horticultural Society Gardens, Wisley, UK. Planted bed WA 0201, c.2002.
*Royal Botanic Gardens, Kew, UK. Acc. no. not known.
* Wijdemeren City Council, Netherlands, Elm collection. Five trees Planted Overmeerseweg, Nederhorst den Berg 2015.

Nurseries

North America

Carlton Plants, LLC
, Dayton, Oregon, US.
Charles Fiore Nurseries
Prairie View, Illinois, US.
Johnson Farms
Deerfield, New Jersey, US.
Riveredge Farms
Atlanta, Georgia, US.
Sharp Top Trees
White, Georgia, US.
The Botany Shop Garden Center
Joplin, Missouri, US.

References

External links

Photograph from 2002 of Princeton elms lining Washington Road in Princeton, New Jersey

{{Elm species, varieties, hybrids, hybrid cultivars and species cultivars , state=collapsed

American elm cultivar
Ulmus articles with images
Ulmus