Infection sources of Pestalotiopsis sensu lato related to loquat fruit rot in Nagasaki Prefecture, Japan

Fruit rot of loquat [Eriobotrya japonica (Thunb.) D. Don], a postharvest disease caused by Pestalotiopsis sensu lato, seriously damages loquat fruit in Nagasaki Prefecture, where the most loquats are produced in Japan. The disease cycle of fruit rot in the orchard has not been adequately elucidated, although gray leaf spot caused by species of Pestalotiopsis s.l. has been suggested as an inoculum source for fruit rot. To determine the inoculum source of loquat fruit rot, fungal isolates of Pestalotiopsis s.l. from rotten fruits, diseased leaves, and healthy flowers of plants with gray leaf spots were tested for pathogenicity on fruits and leaves with and without wounding. Isolates from rotten fruits were identified as Neopestalotipsis by molecular phylogenetic analyses and were genetically close to the isolates identified as Neopestalotiopsis from leaves and flowers and were pathogenic on leaves and fruits. The other isolates, identified as Pestalotiopsis s.s. from healthy flowers and rotten fruits were pathogenic only on fruits. Thus, Neopestalotiopsis fungi from gray leaf spot are the causal agents of fruit rot. The inoculum source of Pestalotiopsis s.s. fungi was not determined.