Fruit Rot of Papaya Caused by Fusarium spp. in Korea

Fruit rot symptoms were observed in papaya trees (Carica papaya) grown in a greenhouse in Gokseong, Korea, during disease surveys in 2021 and 2022. The symptoms developed from the fruit ends, and white hyphae grew on the lesions. The incidence of diseased papaya fruits in the investigated greenhouse was 0.5–1.0%. Six single-conidium isolates were obtained from the diseased fruits and identified as Fusarium sp. based on their morphological characteristics. Phylogenetic analysis of the isolates revealed that the isolates were divided into two distinct groups. One group consisting of two isolates clustered with Fusarium bostrycoides, while another group consisting of four isolates did not cluster with any reported Fusarium spp. The four Fusarium sp. isolates are considered to be a new species and need to be studied further. The isolates of F. bostrycoides and Fusarium sp. were tested for their pathogenicity to papaya fruits through artificial inoculation. Both the Fusarium spp. isolates induced fruit rot symptoms of papaya, which were similar to those observed in the investigated greenhouse. This is the first report of F. bostrycoides and a new type of Fusarium sp. causing fruit rot in papaya.