First Report of Tomato Spotted Wilt Tospovirus Infection of Watermelon in Georgia

In 1996, volunteer watermelon plants in a tobacco field in Coffee County, GA, exhibited foliar symptoms that included necrotic ring spots and veinal necrosis. Watermelon plants from experimental plots of the Coastal Plain Experiment Station in Tifton, GA, similarly showed necrotic lesions, often resulting in necrotic ring spots during the late summer of 1997. Out of 16 samples tested for the presence of tomato spotted wilt tospovirus (TSWV) with a commercially available enzyme-linked immunosorbent assay (ELISA) kit (Agdia, Elkhart, IN), six were positive for TSWV. Primers specific to the nucleocapsid gene of TSWV were used in a reverse transcription-polymerase chain reaction assay (RT-PCR) (1) to verify the presence of TSWV. RT-PCR gave an expected PCR product of approximately 350 bp. The amplicon was cloned in pGEM-T vector and the recombinant clone was sequenced. The sequence of the cloned PCR product confirmed the identity of TSWV, thus verifying TSWV infection of watermelon. The potential impact of TSWV on watermelon crop in Georgia will be investigated. This is the first report of natural infection of watermelon by TSWV in Georgia. Reference: (1) H. R. Pappu et al. Tobacco Sci. 40:74, 1996.