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Since 2002, papaya black rot has been spreading over several islands of Okinawa Prefecture, Japan. To devise a prevention strategy for the disease, microbiological research on the pathogen was conducted. Twelve strains were isolated from papaya infected with black rot showing symptoms such as water‐soaked lesions on stems and petioles, black spots on fruits, and rotted leaves turning yellow with necrotic spots. Through Koch's postulates, we confirmed that the isolated strains caused papaya black rot. Bacteriological assays showed that the strains have characteristics different from the type strains of Erwinia mallotivora, E. papayae, and E. psidii. Moreover, 16S rDNA sequence similarity searches showed that the isolated strains had less than 98.6% similarity with type strains. Additionally, phylogenetic analysis of 16S rDNA sequences suggested that the isolated strains were possibly a novel species belonging to the genus Erwinia, as the strains formed an independent cluster and had low sequence similarity with the type strains. Earlier studies indicated that papaya black rot is caused by E. cypripedii. Therefore, we propose to add the Erwinia sp. isolated in this study to the list of papaya black rot pathogens.

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Fruitlet core rot of pineapple (Ananas comosus) has been found in Okinawa Prefecture, Japan since a few decades ago. A fungus frequently isolated from the diseased fruits was identified as Fusarium ananatum based on morphological and cultural characteristics and molecular analyses of EF-1α,β-tubulin and histone H3 DNA sequences. The isolates reproduced the symptoms on pineapple fruits after inoculation using toothpicks and were reisolated from the inoculated symptomatic fruits. This is the first report of fruitlet core rot of pineapple caused by F. ananatum in Japan, and we propose the Japanese name "shoka-fuhai-byo" of pineapple.