PRELIMINARY STUDIES ON “CITRUS FOAMY FLUX” IN BASILICATA, ITALY
In the Autumn of 2018 and 2019, during surveys to verify the phytosanitary status of citrus orchards located in the countryside of Scanzano Ionico (Basilicata, Italy), on trunks and branches of 5-years-old sweet orange cv. Fukomoto grafted on Carrizo citrange, located in the countryside of Scanzano Jonico, copious whitish foamy exudates were observed. Alongside the flows the bark appeared cracked. The percentage of symptomatic plants was around 5-10%. Trees with the described symptoms were declining and with poor production. In order to identify the possible causes, specific investigations were conducted. In particular, phytopathological and chemical analyses of symptomatic plants were carried out. The results of chemical analyses showed that the nutritional levels were normal; also, virological analyses resulted negative. A yeast (and occasionally a bacterium), was constantly isolated from the symptomatic tissues and exudates, which were identified molecularly by PCR and subsequent gene analysis. The obtained PCR amplicons were sequenced and compared with those already present in the databases (NCBI) showing high similarity with those of Torulaspora delbrueckii and Zymobacter palmae. Further studies must be conducted to fulfill Koch's postulates, in order to verify the role played by T. delbrueckii and/or Z. palmae in determining the observed symptoms, and also to check if other factors, biotic or abiotic, are involved
