Xylella fastidiosa, a devastating xylem-restricted quarantine bacterium was found to be the cause of OQDS. However, surveys conducted in Apulia region starting from 2013 have shown that symptomatic olive trees are often infected by a complex of complementary pests, including a number of vascular fungi species. This research has as purpose to investigate the vascular fungi especially those belonging to Botryosphaeriaceae spp. occurring in olive tree showing OQDS.A survey was conducted throughout six months in Apulia region to put the light on vascular fungi; samples were collected from the base of the trunk, the trunk and the branches of olive trees infected with Xf. Isolation and morphological of vascular fungi was performed from previously collected samples. Further morphological and molecular characterization by amplification and sequencing of 5.
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8S rDNA gene followed by phylogenetic analysis were performed on Botryosphaeriaceae isolates to characterize them to species level. Results indicate that besides Xylella fastidiosa 21 group of vascular fungi were isolated from olive trees showing OQDS with dominance of Phaeoacremonium, Botryospheriaceae and Acremonium species. Both morpholgical and molecular identification approaches carried out on a sub-collection of 150 of Botryosphaeriaceae isolates has shown that all of them resulted to belong to one genus which is Neofusicoccum, and to three species with dominance of Neofusicoccum mediterraneum (91 isolates) over Neofusicoccum parvum (34 isolates) and Neofusicoccum luteum (25 isolates).To assess the disease severity and to confirm the involvement of vascular fungi in wilt and decline of olive trees, pathogenicity assays should be performed on shoots of young olive plants.
