Identification and characterization of fungi pathogen causing fruit rot disease of watermelon (Citrullus lanatus)

Postharvest rot caused by Fusarium species is considered one of the most devastating diseases limiting production and commercialization of water melon worldwide. Two economically important fungi species are generally responsible for fruit rot in watermelon. The aim of this study was to identify and characterize the fruit rot causing pathogen in watermelon in Ibadan Nigeria. Symptomatic watermelon leaves and fruits expressing severe wilt and rot were collected and cultured on solidified Potato dextrose agar. Pure culture of the isolated pathogen was identified based on morphological and molecular characterization as a new species of Fusarium viz. Fusarium chlamydosporium. The pathogenicity of F. chlamydosporum confirmed on watermelon and golden melon fruits revealed its capability to cause infection on healthy fruits. Golden melon fruits artificially inoculated with F. chlamydosporum isolate had higher rot diameter (81.7 mm) than watermelon (40.0 mm), disease incidence and severity also was significantly higher in golden melon with 88.3% and 100.0% respectively. To our knowledge this is the first report of F. chlamydosporum as a causal pathogen of watermelon wilt and fruit rot disease in Nigeria.