During the 2000 growing season, tobacco plants showing blotching of the leaves with light and dark green areas suggestive of Tobacco mosaic virus (TMV) infection were observed in several counties in Georgia. Symptomatic plants appeared in the field within 4 weeks after transplanting. The incidence in individual fields was as high as 100%. A survey was conducted in several tobacco-growing counties, and the presence of TMV was verified by enzyme-linked immunosorbent assay (ELISA). Symptomatic plants were collected from the following 20 counties: Appling, Bacon, Berrien, Coffee, Colquitt, Cook, Echols, Evans, Grady, Irwin, Jeff Davis, Lanier, Lowndes, Montgomery, Pierce, Tattnall, Tift, Toombs, Ware, and Wayne. Of the 79 samples tested by ELISA, TMV was found to be present in 76 samples. This high degree of incidence of TMV in Georgia's tobacco has not been observed in the past. Although the specific reasons are not clear, all severe cases of TMV were observed in two varieties, NC71 and NC72, or plants of other varieties out of beds or plant houses that held these two varieties and were clipped with the same mower. While TMV and Potato virus Y (PVY) were found most prevalent in Georgia's flue-cured tobacco in 1999 (2), none of the plants tested were positive for PVY in 2000. Cucumber mosaic virus was reported to be more common in Florida during the last 3 years (1). The severe outbreak of TMV highlights the importance of preventive measures such as observing sound sanitation practices.
References: (1) T. A. Kucharek et al. Plant Dis. 82:1172, 1998; (2) H. R. Pappu et al. Plant Dis. 84:201, 2000.
