Ulmus 'New Horizon'

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Ulmus 'New Horizon'
Ulmus New Horizon USA 2011a (c) Eisele.jpg
'New Horizon', Wisconsin-Madison University
Genus Ulmus
Hybrid parentage U. davidiana var. japonica × Ulmus pumila
Cultivar 'New Horizon'
OriginWARF, Wisconsin, USA

Ulmus 'New Horizon' is an American hybrid cultivar raised by the Wisconsin Alumni Research Foundation (WARF), from a crossing of the Japanese Elm clone W43-8 = 'Reseda' (female parent) with Siberian Elm clone W426 grown from seed collected from a street tree at Yankton, South Dakota. [1] Tested in the US National Elm Trial coordinated by Colorado State University, 'New Horizon' averaged a survival rate of 74% after 10 years. [2] 'New Horizon' was patented in the US in 1994, while in Europe, it is marketed as one of the 'Resista' elms protected under EU breeders' rights (EU council decision 2100/94).

Contents

Description

Unlike its elder stablemate 'Sapporo Autumn Gold', 'New Horizon' initially has a compact, pyramidal form, with comparatively dense foliage comprising glabrous, dark-green, elliptical leaves < 12 cm long by 7 cm broad, occasionally without the asymmetric bases typical of the genus. [3] The perfect, apetalous wind-pollinated flowers appear in March, followed by the seeds in April; flowering, and consequent fruiting, is sparse, in common with its female parent Japanese Elm, and usually begins when the tree is aged 8 years. [4] [5]

The tree's growth habit is unusual; in an assessment at U C Davis as part of the National Elm Trial, its stem diameter increased faster than any other of the 15 cultivars, but increase in height, averaging 0.9 m per annum, made it one of the slowest growing, vertically.

In commerce in the US, the tree is occasionally propagated by grafting onto an Ulmus pumila rootstock, rather than simply rooting cuttings as normally practiced in North America and Europe.

Pests and diseases

'New Horizon' has a very high resistance to Dutch elm disease, rated 5 out of 5 in Europe; [6] it is also resistant to elm leaf miner, and verticillium wilt. [7] However, it has proven susceptible to attack by elm leaf beetle Xanthogaleruca luteola [8] and Japanese Beetle in the United States. [9] Up until its patenting in 1993, no Coral Spot fungus infection had been observed in the US. [4]

Cultivation

The tree has not been an unqualified success. In the elm trials conducted by the University of Minnesota, 'New Horizon' was found to need relatively high levels of maintenance, largely owing to its predilection for co-dominant leaders and heavy side branches. [10] In the Netherlands, removal of sideshoots from the lower trunk was found to be necessary twice a year. In trials in eastern Arizona it often exhibited > 25% crown dieback over winter and a very high level of leaf scorch in summer. The tree is currently being evaluated in the National Elm Trial coordinated by Colorado State University.

'New Horizon' was introduced to Europe by the Conrad Appel nursery (ceased trading 2005) in Darmstadt, Germany, which propagated the tree under licence as one of the hybrid elms offered in the Resista series ; the trees were originally propagated by grafting, but this practice proved unsuccessful owing incompatibility with the rootstock; 50 trees planted in Pau, France, had to be replaced. [11] The tree is currently propagated by Eisele GmbH.

The tree was introduced to the UK and Ireland by Hillier Nurseries, who have sole distribution rights. 'New Horizon' was named 'Best New Plant Variety' by Horticulture Week in 2005, however, an assessment by Butterfly Conservation found its growth on heavy, poorly drained ground negligible. Nevertheless, the tree has tolerated flooding, by both freshwater in England, and seawater along the Baltic coast in Germany . Trees at exposed sites in Hampshire exhibited much the same degree of dieback experienced in the Arizona trials despite the extreme differences in climate. However no losses have been sustained, and in sheltered conditions on deep loam over chalk, 'New Horizon' grew healthily if relatively slowly, increasing in height by approximately 50 cm per annum, less than half the speed of the Dutch hybrids such as 'Dodoens' planted with it. The trees in the English trials first flowered aged 10 years, in late March. [12]

In 2004, 80 trees were donated to the Greater London Council as part of the grower's European Elm City promotion; similar gifts were also made to Belfast, Cardiff (Pontcanna Fields, 100 trees planted in 2004), [13] and Hamburg (the central City Park). [14] [15] In 2010, 100 trees were planted in the London borough of Enfield to aid and abet the conservation of the White-letter Hairstreak Satyrium w-album . Another hundred were included in the tree planting at the Olympic Park. [16] Forty have been planted in Richmond Park, near the Dysart gate. Three, planted in 2014 as part of a resistant elms trial, stand by the Isis in Christ Church Meadow, Oxford. [17] [18]

Conservation

'New Horizon' was found hosting the endangered White-letter Hairstreak at the Vauxhall Pleasure Gardens, London, in 2017; this is the first recorded instance of the butterfly breeding on the cultivar in the UK. [19]

Accessions

North America

Europe

Nurseries

North America

Europe

Related Research Articles

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<i>Ulmus davidiana <span style="font-style:normal;">var.</span> japonica</i> Variety of tree

Ulmus davidiana var. japonica, the Japanese elm, is one of the larger and more graceful Asiatic elms, endemic to much of continental northeast Asia and Japan, where it grows in swamp forest on young alluvial soils, although much of this habitat has now been lost to intensive rice cultivation.

<i>Ulmus</i> Nanguen Elm cultivar

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<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> Regal Elm cultivar

Ulmus 'Regal' is an American hybrid elm cultivar developed by the University of Wisconsin–Madison and released in 1983. 'Regal' was derived from seeds arising from the crossing of the Dutch hybrid clones 'Commelin' and '215' sent in 1960 by Hans M. Heybroek of the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen, Netherlands.

<i>Ulmus</i> Sapporo Autumn Gold Elm cultivar

Ulmus 'Sapporo Autumn Gold' is one of the most commercially successful hybrid elm cultivars ever marketed, widely planted across North America and western Europe, although it has now been largely supplanted by more recent introductions. Arising from a chance crossing of the Japanese elm and Siberian elm, seed was sent in 1958 by Prof. Nobuku Takahashi and his colleagues at the Sapporo Botanical Garden of Hokkaido University, Sapporo, to Eugene Smalley at the University of Wisconsin–Madison. The patent issued in 1975 has expired, and there are now no propagation restrictions.

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

Ulmus gausseniiW. C. Cheng, the Anhui, or hairy, elm, is a medium size deciduous tree whose natural range is restricted to the valleys of the Langya limestone mountains of Chu Xian in Anhui Province, eastern China. The tree was most commonly found on the flood plains, indicating a tolerance of periodic inundation. However, U. gaussenii is now possibly the rarest and most endangered elm species, with only approximately 30 trees known to survive in the wild in 2009.

<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.

<i>Ulmus</i> Morton Glossy Elm cultivar

Ulmus 'Morton Glossy' is a hybrid cultivar raised by the Morton Arboretum, Illinois. Originally named 'Charisma' until it was realized that name had already been registered for another plant, the tree was derived from a crossing of two other hybrid cultivars grown at the Morton: Accolade and Vanguard. Tested in the US National Elm Trial coordinated by Colorado State University, Triumph averaged a survival rate of 86% after 10 years. Triumph was introduced to the UK in 2006 by the Frank P. Matthews nursery in Worcestershire.

<i>Ulmus</i> Columella Elm cultivar

Ulmus 'Columella' is a Dutch elm cultivar raised by the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen. Originally thought to have been derived from a selfed or openly pollinated seedling of the hybrid clone 'Plantyn', DNA analysis later determined it arose from a cross of 'Plantyn' and Ulmus minor. Sown in 1967, it was released for sale in 1989 after proving extremely resistant to Dutch elm disease following injection with unnaturally high doses of the pathogen, Ophiostoma novo-ulmi. However, propagated by grafting onto wych elm rootstocks, graft failure owing to incompatibility has become a common occurrence in the Netherlands.

<i>Ulmus</i> Cathedral Elm cultivar

Ulmus 'Cathedral' is a hybrid cultivar raised at University of Wisconsin–Madison patented in 1994. Arising from a chance crossing of the Japanese elm and Siberian elm, seed was sent in 1958 by Prof. Nobuku Takahashi and his colleagues at the Sapporo Botanical Garden of Hokkaido University, Sapporo, to Eugene Smalley at Wisconsin–Madison; 'Cathedral' is thus a sibling of 'Sapporo Autumn Gold'.

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

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

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<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.

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<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.

<i>Ulmus</i> Rebona Elm cultivar

Ulmus 'Rebona' is an American hybrid cultivar raised by the Wisconsin Alumni Research Foundation (WARF) as selection 'W916', derived from a crossing of Japanese Elm clone W43-8 = 'Reseda' with Siberian Elm clone W426 grown from seed collected from a street tree at Yankton, South Dakota. The tree was registered in 1993 by Conrad Appel KG, of Darmstadt and is a sibling of 'New Horizon'. In Europe, 'Rebona' is marketed as a Resista elm protected under E U breeders' rights.

References

  1. ↑ Santamour, Frank S.; Bentz, Susan E. (May 1995). "Updated Checklist of Elm (Ulmus) Cultivars for use in North America". Journal of Arboriculture. 21 (3): 122–131. Retrieved 20 June 2016.
  2. ↑ Griffin, J.; et al. (2017). "Ten-Year Performance of the United States National Elm Trial" (PDF). Arboriculture & Urban Forestry. International Society of Arboriculture, Atlanta, US. 43(3):107–120.
  3. ↑ noordplant.nl, Emerging 'New Horizon' leaves, Amsterdam
  4. 1 2 Smalley, E. & Guries, R. (1993). Patent application: Elm tree named New Horizon. US PP8684 P. U S Patent Office.
  5. ↑ Photographs of 'New Horizon' elms, and leaves,
  6. ↑ Heybroek, H. M., Goudzwaard, L, Kaljee, H. (2009). Iep of olm, karakterboom van de Lage Landen (:Elm, a tree with character of the Low Countries). KNNV, Uitgeverij. ISBN   9789050112819
  7. ↑ Pinon, J. (July 2007). "Les ormes résistants à la graphiose" [Elms resistant to Dutch Elm Disease](PDF). Forêt-entreprise. Paris, France: IDF (175): 37–41. ISSN   0752-5974 . Retrieved 26 October 2017.
  8. ↑ McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, 32–36.
  9. ↑ 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, 15–16. University of Kentucky.
  10. ↑ Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota.
  11. ↑ Pinon, J. (2023). Le retour des Ormes dans les villes françaises. Revue forestière française, 74(3), 347–357. https://doi.org/10.20870/revforfr.2023.7686
  12. ↑ Butterfly Conservation (2023). Disease-resistant elm cultivars , Butterfly Conservation, Lulworth, England.
  13. 1 2 3 4 Ulmus 'New Horizon', Pontcanna Fields, Cardiff; conservationfoundation.co.uk
  14. ↑ Horticulture Week, Haymarket Publishing, London, UK, 24 April 2004
  15. ↑ Gordon Mackenthun: 'Elms, Dutch Elm Disease and the Hamburg Elm Program'
  16. ↑ McEwan, G. (2010). Great British Elm Experiment: nurseries and tree managers work to re-establish trees resistant to Dutch elm disease. Horticulture Week, 9 April 2010, London.
  17. ↑ Tim Richardson, 'Can we resurrect the English elm?', The Daily Telegraph, 6 March 2021
  18. ↑ 'A brief guide to Christ Church Meadow', p.9; chch.ox.ac.uk
  19. ↑ Brookes, A. H. (2022). Great Fontley Elm Trial, 2022 Report. Butterfly Conservation, Lulworth, England.
  20. ↑ "List of plants in the {elm} collection". Brighton & Hove City Council. Retrieved 23 September 2016.
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