Silver Mottle Disease of Watermelon Caused by Tomato Spotted Wilt Virus. M. Iwaki, National Institute of Agro-Environmental Sciences, Kannondai, Yatabe, Ibaraki, 305 Japan. Y. Honda, K. Hanada, and H. Tochihara, National Agriculture Research Center, Kannondai, Yatabe, Ibaraki, 305 Japan; T. Yonaha, University of Ryukyu, Nakakami, Okinawa, 903-01 Japan; K. Hokama, Okinawa-ken Agricultural Experiment Station, Shurisakiyama, Naha, 903 Japan; and T. Yokoyama, Kumamoto-ken Agricultural Experiment Station, Kaminogo, Kumamoto, 861-41 Japan. Plant Dis. 68:1006-1008. Accepted for publication 2 July 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-1006.

The causal virus of the silver mottle disease that occurred in watermelon in Okinawa, Japan, was identified as tomato spotted wilt virus (TSWV) on the basis of particle morphology, host reactions, instability in crude sap, effects of sodium sulfite and l-cysteine on stability, and thrips transmissibility. This is the first report of TSWV naturally infecting Cucurbitaceae.