Symptomatic Citrus trees reveal a new pathogenic lineage in Fusarium and two new Neocosmospora species. Fusarium and Neocosmospora spp. on Citrus

The diversity of fusaria in symptomatic Citrus trees in Greece, Italy and Spain was evaluated using morphological and molecular multi-locus analyses based on fragments of the calmodulin (CAM), intergenic spacer region of the rDNA (IGS), internal transcribed spacer region of the rDNA (ITS), large subunit of the rDNA (LSU), RNA polymerase largest subunit (RPB1), RNA polymerase second largest subunit (RPB2), translation elongation factor 1-alpha (EF-1α) and beta-tubulin (TUB) genes. A total of 11 species (six Fusarium spp., and five Neocosmospora spp.) were isolated from dry root rot, crown, trunk or twig canker or twig dieback of citrus trees. The most commonly isolated species were Fusarium sarchochroum, F. oxysporum and Neocosmospora solani. Three new Fusarium species are described i.e, F. trinacriaensis, belonging to the F. fujikuroi species complex; and F. aeolianicum and F. citricola belonging to the newly described F. citricola species complex. Results of pathogenicity tests showed this new complex to include prominent canker causing agents affecting several Citrus spp. In addition, two new species are described in the genus Neocosmospora, named N. croci and N. macrospora, the latter species being clearly differentiated from most members of this genus by producing large, up to nine-septate sporodochial conidia.