Occurrence of Two Tobamovirus Diseases in Cucurbits and Control Measures in Korea

Two Tobamoviruses, Cucumber green mottle mosaic virus (CGMMV) and Zucchini green mottle mosaic virus (ZGMMV), occurred in Korea in 463 ha in 1998, 33.9 ha in 1999, and 44.2 ha in 2000. CGMMV was detected in watermelon, cucumber, oriental melon, and melon, whereas ZGMMV was mainly detected in zucchini squash. Thirty-six CGMMV isolates wee classified into three types by analysis of single strand cDNA conformational polymorphism (SSCP) of the coat protein gene. In a comparison of serological relationships among CGMMV, ZGMMV, and Kyuri green mottle mosaic virus (KGMMV), the three tobamoviruses specifically reacted with each homologous antibody in the double-antibody sandwich enzyme-linked immunosorbent assay and rapid imunofilter paper assay (RIPA), although ZGMMV and KGMMV were slightly biologcially similar. In a survey of the three tobamoviruses in cucurbitgrowing field in Korea by RIPA, CGMMV and ZGMMV were detected but KGMMV was not found in commercially growing cucurbit crops so far. Seed contamination ratio of CGMMV in bottle gourd seeds tested was 84%, while seed trasmission ratio from the virus-contaminated seeds was 2.0%. Soil transmission ratio was 0-3.5% in fields naturally infested with CGMMV or ZGMMV. Control measures of the virus diseases are roguing and sanitation. These suggest that it is important to rogue the first infected crops, which include the seed and soil, especially early in the season. This may be practicable to control the diseases because CGMMV and ZGMMV have a narrow host range restricted to cucurbitaceous crops.