P-571 - Identification and characterization of Botryosphaeriaceae species causing postharvest diseases on Florida strawberries

Postharvest diseases of strawberries are one of the major factors causing fruit losses and shelf-life decline. During the 2018-2025 fruit seasons, Florida-produced strawberries were obtained from various harvests at different locations and incubated at 22ºC for up to 5 days. Besides other decays, Botryosphaeriaceae disease was observed (up to 3%) from various sample lots. The infected fruit showed gray fungal mycelia that gradually covered the whole fruit. It is important to identify Botryosphaeriaceae species causing this new strawberry disease. Of six representative isolates, five were morphologically identified as Lasiodiplodia spp. and one was Neofusicoccum spp. The molecular identification using PCR amplification of ITS and EF1-α genes with primers ITS1F-F/ITS4-R and EF1-668-F/EF1-1251-R showed that the sequences from 5 isolates had 99.6 to 100% homology with those of ITS (EF622077) and EF1-α (EF622057) from L. pseudotheobromae CBS116459 (ex-type), and the sequences from 1 isolate had 99.8 to 100% identity with those of ITS (FJ900608) and EF1-α (FJ900654) from Neofusicoccum batangarum CBS124923 (ex-type). Phylogenetic analysis results further supported the identification of L. pseudotheobromae and N. batangarum. Pathogenicity tests showed that all isolates were pathogenic to strawberries. The fungal isolates were re-isolated, fulfilling Koch’s postulates. Since strawberry postharvest decay caused by Botryosphaeriaceae species was from preharvest latent infection, the management for this new disease during both preharvest and postharvest stages should be considered.