Disease Note.

Natural Infection of Melon by a Tospovirus in Brazil. L. S. Boiteux, CNPH/EMBRAPA, CP 0218, 70359-970 Brasilia (DF), Brazil. A. C. de Avila, and W. P. Dutra, CNPH/EMBRAPA, CP 0218, 70359-970 Brasilia (DF), Brazil. Plant Dis. 78:102. Accepted for publication 10 September 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0102B.

In July 1991, approximately 3% of melon (Cucumis melo L.) plants in a field at CNPH/EMBRAPA showed chlorosis of new growth, concentric ring spots on leaves and fruit, fruit malformation, and overall stunting. The symptoms were similar to those reported in Japan (2) as the silver mottle disease of watermelon caused by an isolate of tomato spotted wilt virus (TSWV). Concentric necrotic rings and local chlorotic spots were observed in mechanically inoculated tomato (Lycopersicon esculenlum Mill.) cv. Rutgers, jimsonweed (Datura stramonium L), and melon cv. Hale's Best Jumbo plants. Immuno-difusion tests were performed with samples from sap of symptomatic melon plants against an antibody of the typical TSWV species (I). Results indicated that the melon tospovirus isolate was related to but serologically distinct from TSWV. This new disease may be severe in commercial melon plantings, especially in central Brazil. During the dry season, the natural population of viruliferous thrips vectors of tospoviruses dramatically increases in this region