Efficacy of Fungicides for Control of Rice Tungro Disease

Tungro is considered an important disease of rice in Southeast Asia and in the southeastern states of India. Tungro virus disease can be managed through vector control (Bae and Pathak 1969, Shukla and Anjaneyulu 1980, Satapathy and Anjaneyulu 1984). Dubey (1980) reported that Bavistin, a fungicide, was effective in controlling leaf crinkle virus of urdbean. This prompted us to test fungicides for the therapeutic recovery of tungro on rice. We tested 12 fungicides (three granular, three EC formulations, and six wettable powders) under net-house conditions for therapeutic recovery of plants that were previously infected with tungro disease. One-month-old Jaya seedlings were planted in four rows of 10 seedlings per tray. Ten seedlings were healthy and 10 seedlings each of three replications were inoculated with three viruliferous hoppers per seedling in galvanized iron-mesh cages. The top of the cage was covered with muslin cloth and tightened with a rubber band. After symptoms were expressed (about 10–12 d after inoculation), each tray was sprayed with the fungicide at recommended doses at weekly intervals. Five such sprays were given. Virus quantification and symptomatology before the treatments showed a yellow color of the youngest leaf, which is a typical tungro symptom. After treatment with effective fungicides, the yellow color gradually fades away and the plant is able to recover. Two trays were not sprayed with fungicide (each tray has 20 healthy seedlings and 20 inoculated seedlings) and these served as a control. The height of the plants and number of tillers were observed and plant yield determined.