In Italy, 'Plinio' is a rounded tree with a broad crown, the width typically equalling 70% of height, and a short, often bent, trunk. The dark-green leaves are < 6.5 cm long by 3 cm broad and glabrous on both sides, on < 6 mmpetioles.[1][2] Like its compatriot 'San Zanobi', the tree is not possessed of striking autumn colours, the leaves remaining green almost until they fall in late November. The perfect, apetalous wind-pollinated flowers appear in mid March in the UK. The sessilesamarae are round, 17–22 mm in diameter. Seed has exhibited a modest viability of between 10% and 20%.[3]
Leaves
Samarae
'Plinio' on fertile soil
Pests and diseases
'Plinio' has a very high resistance to Dutch Elm Disease. In trials conducted by the Istituto per la Protezione delle Piante, Florence, 'Plinio' sustained 7.8% defoliation and 3.9% dieback when inoculated with unnaturally high concentrations of the fungal pathogen, compared with 4.7% / 0.0% resp. for 'Morfeo', 50% / 35.5% resp. for 'Lobel', and 95% / 100% for 'CNR118', a Field Elm (Ulmus minor) native to Italy. [1]
Cultivation
Fast growing (though slower than its stablemate 'San Zanobi') in Italy, where it commences flowering in its third year.
The tree is only commercially available outside Italy by mail order. It was introduced to the UKbyButterfly Conservation in 2003 and is being evaluated at several sites in Hampshire, where it has been found to be particularly successful on thin dry rendzinas. However on more fertile soils, the relatively sparse and splaying top growth often exceeds stem and root development, necessitating judicious pruning and stake support for up to five years. [3] 'Plinio' is not known (2013) to have been introduced to North AmericaorAustralasia.
^ abSantini A., Fagnani A., Ferrini F. & Mittempergher L., (2002) 'San Zanobi' and 'Plinio' elm trees. [1]HortScience 37(7): 1139-1141. 2002. American Society for Horticultural Science, Alexandria, VA 22314, USA
^Santini A., Fagnani A., Ferrini F., Mittempergher L., Brunetti M., Crivellaro A., Macchioni N., Elm breeding for DED resistance, the Italian clones and their wood properties. [2]Invest Agrar: Sist. Recur. For. (2004) 13 (1), 179–184. 2004.
^ abBrookes, A. H. (2015). Disease-resistant elms, Butterfly Conservation trials report, 2015 Butterfly Conservation, Hants & IoW Branch, England. [3]
