Ulmus 'Wanoux' (selling name) is a Dutch hybrid cultivar raised at the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen, from an open pollination of 'Plantyn'. Originally identified as clone No. 762, it was selected for assessment by the French Institut National de la Recherche Agronomique (INRA), which patented it as 'Wanoux' in 2006.
was introduced to the UK by the Hampshire & Isle of Wight Branch, Butterfly Conservation, in 2008, as part of its assessment of DED-resistant cultivars as potential hosts of the endangered White-letter Hairstreak.[1] [2]
Unlicenced propagation of is prohibited in Europe inc. the UK under Certificat d'Obtention Végétale (COV) EU 24403 until its expiry on 31 December 2039.
is a narrow tree primarily intended for street planting. The glossy, dark-green leaves, < 11 cm long by 8 cm wide, are coarsely toothed and have conspicuous venation.[3] The samarae are sub-orbicular, almost cordate, typically 15 mm long by 13 mm wide, the seed slightly nearer the shallow notch. Towards the end of the season, the leaves suffer from various afflictions and can appear shabby. Leafing is late, but not quite as late as its stablemate . Many minor buds fail to burst, so that young plants are rather sparsely furnished; in combination with the tree's limited lateral development, this can lead to a skeletal appearance.[4] The tree readily suckers from the roots, notably on chalk.
Tests in France by INRA found the tree to be 'highly resistant' to Dutch elm disease, exhibiting the lowest wilting percentage of all the clones trialled, making it comparable with 'Sapporo Autumn Gold'[5] However, the presence of U. wallichiana in the ancestry of poses the risk of susceptibility to elm yellows (phloem necrosis), which seriously damaged its Dutch stablemate 'Lobel' used as a control in the Italian elm breeding programme.[6] The clone has also proven susceptible to Coral spot fungus Nectria cinnabarina in the Netherlands.[7]
In trials in southern England, the leaves were found to remain completely free of Black Spot.[1]
has moderate vigour, attaining a height of 14 m at 20 years of age in France.[3] The tree is reputedly easily propagated from cuttings. was introduced to North America in 2010, with the supply of two small specimens to the USDA, Washington, D.C., released from quarantine in 2013. is reported "the most successful so far" (2021) of a 2014 trial planting of elms at Lees Court, Kent.[8] Among urban introductions in the UK are three specimens, planted in 2014, towards the east end of Broad Walk, Christ Church Meadow, Oxford,[8] [9] and four in Inverleith Park, Edinburgh, planted c.2012. 300 VADA were planted circa 2019 in the Parc de Sceaux, southern Paris, and early in 2021 92 were planted in the jardin des Tuileries.[10] is not known to have been introduced to Australasia.
Former French prime minister Lionel Jospin insisted on planting an elm, the tree of the Left when, in keeping with tradition, he was obliged to plant a tree in the garden of the Hôtel Matignon, his official residence in Paris, in 1998. He chose, then still known only by its Dutch trial identity of '762'. The Left, however, does not have a monopoly on elms. 'The Queen's Elm' planted on the main lawn of Holyrood Palace, Edinburgh, near the ruined Holyrood Abbey to mark the Diamond Jubilee of Elizabeth II (2012), is also an Ulmus .[11]
The registered cultivar name 'Wanoux' is a contraction of Wageningen and Champenoux, the locations of the Dutch and French research stations. The selling name VADA is the ancient Roman name for the Dutch town of Wageningen, where the clone was raised.