Prima segnalazione di Pestalotiopsis spp. su nocciolo in Italia.

Italy is the first European producer of hazelnuts (Corylus avellana L.) and second in the world after Turkey. The orchards are mainly located in Piedmont, Lazio, Campania and Sicily. In 2013 a sample of hazelnut leaves from Piedmont, showing necrotic spots, has been analyzed. The aims of this work have been to identify the causal agent and verify Koch's postulates, since specific references in literature are not present. Colonies with a white aerial, dense mycelium with black acervuli close to center, similar to ink drops, grew really fast from hazelnut leaf samples plated on PDA. At light microscope the conidia appeared ellipsoid 4-septate, with three brown central cells, the basal and apical cells hyaline and with appendages. Morphologically the fungus was identified as Pestalotiopsis spp. Molecular identification has still not been successfully applied for species-level differentiation. Furthermore pathogenicity tests on leaves, both in vitro and in vivo, were set up at different temperatures. Positive response and a better infection resulted at 20°C. Pestalotiopsis was reisolated from the leaf tissues artificially infected. Pestalotiopsis spp. on hazelnut has been reported in different countries, in particular P. macrospora was found to be pathogenic on leaves and twigs in İran and P. guepinii in Turkey. Furthermore in 2015 Pestalotiopsis spp. was reported to cause disease on halzenut fruit clusters in Turkey, causing yield reduction. This work is the first report of Pestalotiopsis in hazelnut in Italy. Due to the economic importance of this crop in Italy, the incidence of this fungus should be monitored.