SEVERE OUTBREAK OF PSEUDOMONAS-SYRINGAE PV AVELLANAE ON HAZELNUT IN ITALY

Pseudomonas syringae pv. avellanae, the causal agent of bacterial cank er of hazlenut, has been isolated for the first time in Italy. Biochem ical tests were consistent with the type-strain of the microorganism a nd whole-cell protein profiles of the studied isolates were similar to those of the type-strain. When artifically inoculated, either in summ er or in autumn, the isolates incited the same symptoms as those obser ved in the field. The main symptoms are the failure of the buds to swe ll or their withering after breaking in spring; the chlorosis of the f oilage and rapid withering of the leaves that remain attached on the t wigs during summer; dark brown discolouration of the dark and cambium, necrosis in the primary roots and the final dieback of the plant. The pathogen killed more than 1,800 adult hazelnut plants in one orchard within a period of five years. The main differences of the symptomatol ogy between bacterial canker and bacterial blight of hazelnut, caused by Xanthomonas campestris pv. corylina, and the ''seccume'' of the haz elnut are briefly discussed.