DETECTION OF PSEUDOMONAS AVELLANAE AND THE BACTERIAL MICROFLORA OF HAZELNUT AFFECTED BY ‘MORIA’ IN CENTRAL ITALY
S. Loreti, A. Gallelli, D. De Simone, A. Bosco
The presence of Pseudomonas avellanae and the bacterial flora associated with different hazelnut organs, was monitored from 2004-2007 in two areas of the province of Viterbo (central Italy). Samples were randomly selected from three orchards affected by the disease known as ‘Moria’ (dieback): symptomatic twigs or branches (2004-2005 and 2007), symptomless suckers (2004-2006), leaves and pollen (2006-2007). The presence of P. avellanae was examined by PCR assay (PCRWA/WC) and also checked by isolation, enabling us to verify the reliability of the PCR. The incidence of P. avellanae in symptomatic samples ranged from 9 to 38% in the areas monitored. P. avellanae was found in up to 3% of symptomless suckers whereas pollen and leaves all tested negative. PCRWA/WC proved to be more reliable than isolation for the detection of P. avellanae. The association of bacteria with different hazelnut organs was assessed by isolation followed by 16S rDNA sequencing. The recovered isolates were closely related to bacteria mainly associated with the environment, with the exceptions of Brenneria quercina and Pseudomonas syringae. B. quercina was rarely recovered, and only from leaf surfaces. On the other hand, P. syringae pv. syringae was frequently isolated from buds, bark tissue and leaves. A preliminary characterization of this P. syringae population by rep-PCR is reported.