Characterization of Neopestalotiopsis Species Associated with Strawberry Crown Rot in Italy

Different Pestalotiopsis-like species have been reported in strawberry worldwide, as agents of leaf spot, root rot, and crown rot. The identification of Pestalotiopsis-like fungi is based on both molecular and morphological analyses to discriminate between species and clarify phylogenetic relationships. Recent studies have provided robust multi-locus analyses, which reclassified most Pestalotiopsis-like isolates associated with strawberry root and crown rot diseases as Neopestalotiopsis spp. Numerous disease outbreaks have been observed in strawberry fields in Italy in recent years, showing that Neopestalotiopsis is an emerging pathogen. A survey was conducted in Northern Italy during 2022–2023 to investigate the diversity and distribution of Neopestalotiopsis species. Morphological and phylogenetic characterization, based on ITS, tef1 and tub2, led to the identification of four species: Neopestalotiopsis rosae, N. iranensis, N. hispanica (syn. vaccinii) and N. scalabiensis. Based on our results from multi-locus phylogenetic analysis, N. hispanica and N. vaccinii were grouped in the same cluster; thus, they were confirmed to be the same species. Pathogenicity tests with representative isolates of each species were conducted on strawberry ‘Portola’ transplants. All isolates were shown to be wound pathogens in strawberry, causing crown rot, and were successfully re-isolated. Neopestalotiopsis rosae was confirmed to be the most dominant and virulent species associated with these symptoms, as well as the most dominant among the obtained isolates. To the best of our knowledge, this work represents the first report of N. scalabiensis being associated with the crown rot of strawberry in Italy and the first report of N. iranensis in association with the crown rot of strawberry worldwide.