Ochraceocephala foeniculi gen. et sp. nov., a new pathogen causing crown rot of fennel in Italy.

A new disease of fennel is described from Sicily (southern Italy). Surveys of the disease and sampling were conducted during spring 2017 and 2018 in Adrano and Bronte municipalities (Catania province) where this crop is widely cultivated. Isolations from the margin of symptomatic tissues resulted in fungal colonies with the same morphology. Pathogenicity tests with one isolate of the fungus on 6-month-old plants of fennel reproduced similar symptoms to those observed in nature. Inoculation experiments to assess the susceptibility of six different fennel cultivars to infection by the pathogen showed that the cultivars 'Narciso', 'Apollo', and 'Pompeo' were more susceptible than 'Aurelio', 'Archimede', and 'Pegaso'. Phylogenetic analyses based on a matrix of the internal transcribed spacer (ITS), the large subunit (LSU), and the small subunit (SSU) rDNA regions revealed that the isolates represent a new genus and species within the Leptosphaeriaceae, which is here described as Ochraceocephala foeniculi gen. et sp. nov. This study improves the understanding of this new fennel disease, but further studies are needed for planning effective disease management strategies. According to the results of the phylogenetic analyses, Subplenodomus iridicola is transferred to the genus Alloleptosphaeria and Acicuseptoria rumicis to Paraleptosphaeria.