Pleiocarpon gen. nov. and a new species of Ilyonectria causing basal rot of Strelitzia reginae in Italy

During 2015, a new basal rot disease was observed on potted plants of Strelitziareginae in an ornamental nursery located in eastern Sicily. Isolations from symptomatic parts of these diseased plants consistently yielded cylindrocarpon-like isolates. Multigene analyses of the partial gene regions of 28S large subunit nrDNA, β-tubulin, histone H3, translation elongation factor 1-alpha, internal transcribed spacer region and intervening 5.8S nrRNA gene, and RNA polymerase II second largest subunit genes, supported by morphological characters supported the recognition of a new genus, Pleiocarpon based on P. strelitziae sp. nov., and a new Ilyonectria species, described here as I. strelitziae sp. nov. The pathogenicity of both I. strelitziae and P strelitziae were confirmed on young plants cultivated under controlled conditions in a growth chamber. Both cylindrocarpon-like fungi were pathogenic to S. reginae and reproduced symptoms similar to those observed in the nursery. Of the two species, P strelitziae was more aggressive than I. strelitziae , resulting in the death of all inoculated plants.