Watermelon, Citrullus lanatus (Thumb.) is an annual trailing creeper belonging to the family cucurbitaceae. It occupies a pivotal position among fruit vegetables. Among the diseases affecting watermelon, bud necrosis disease has emerged as a serious threat in India. Recently, bud necrosis a Tospovirus disease, has emerged as a serious problem of watermelon cultivation in Kerala. For the biological characterization of the virus mechanical transmission was standardized with different buffers at four pH level (7.0, 7.2, 7.4 and 7.6). Under artificial inoculation, symptom initiated as curling, crinkling and mottling of leaves. Citrate phosphate buffer 0.1 M (pH 7.2) showed the maximum transmission (72.22 %) with minimum incubation period (8 days). This is the first report on the efficacy of Citrate phosphate buffer.
