Alternaria alternata as the cause of decline and necrosis on olive tree cuttings in Greece

In 2018, decline and necrosis were observed on olive tree cuttings ( Olea europaea ) in a nursery in northern Greece. The pathogen was identified as Alternaria alternata on the basis of conidia morphology and sequence analysis of the internal transcribed region (ITS) and part of the elongation factor 1a (EF-1a). The endopolygalacturonase ( endoPG ) and the Alternaria major allergen ( Alta1 ) genes were also amplified. A pathogenicity test was performed and Koch's postulates were confirmed by re-isolation of the fungus A. alternata from artificially inoculated cuttings. This is the first report of A. alternata as the cause of decline and necrosis on olive tree cuttings in Greece.