Abstract

The efficacy of plant products and oils in reducing the infection of rice by yellow dwart MLO was tested. Leaf extracts of young and matured leaves of Neem, Mirabilis jalapa, Catharanthus roseus, Maize and Nerium sp were applied on TN 1 rice plants. The infective leafhoppers were caged on treated and control plants at 1, 24, 48 and 72 hr after applications of leaf extracts. Neem leaf (both matured and young) recorded low infection (40%) as compared to other treatments and control (82.2%). The incubation period in the neem leaf extract treated plants increased to 40.3 days as against 28.5 days in control. The reduction in infection and increase in incubation period were observed more significantly in plants inoculated one hr after the treatment than in plants inoculated at 24, 48 and 72 hr after the treatment. Of the three oils tested namely, Neem, pungam and illupai oils, Neem oil recorded lower per cent infection (13.3%) as compared to illupai oil (26.7%), pungam oil (20.0%) and control (82.2%). The incubation period was also increased significantly in the plants treated with oils. As in the case of leaf extracts, the favourable effect on infection and incubation period was reduced as the interval between application of oils and inoculation increased.

Keywords: Rice yellow dwarf, Leaf extracts, oils.