OCCURRENCE OF ERWINIA NIGRIFLUENS ON ENGLISH WALNUT JUGLANS REGIA IN THE VENETO REGION NORTHERN ITALY
A. Saccardi, V. Bonetti, A. Melegatti, M. Cristanini
In the period 1995-1997, in the Padua province of the Veneto region, bark cankers were observed on 15- 20 year old walnut trees (Juglans regia L.) and young walnut trees in the nursery. On the older trees the cankers on the trunks and on the proximal part of the scaffold branches consisted of brownish areas that often produced drops of exudate. On young trees the cankers caused longitudinal grooves, often brownish and severe deformation of the trunks. Gram-negative bacteria isolated from both types of canker and purified were identified as Erwinia nigrifluens based on phenotypic traits (including fatty acid profiles) and pathogenicity. The symptoms caused on young trees were unusual for E. nigrifluens. This was the first report of E. nigrifluens in Italy.