Dynamics of tungro disease and its vector population on intercropping of rice varieties

Tungro is one of the major diseases has ability reduce the yield potential of rice. The disease was caused by rice tungro baciliform virus (RTBV) and rice tungro spherical virus (RTSV). Both of virus only transmitted by green leafhoppers, Nephotettix virescens in a semi- persistent manner. The research purpose is to control tungro disease and its vectors as well as the diversity of natural enemies by applying the intercropping method of several rice plant varieties. The optimum of disease incidence in 11 weeks observation on the variety of Ciherang, Inpari 32, Inpari 36, and IR 64 planted in intercropping was 7.8%, 7.3%, 3,8%, and 6.3%. Whereas, the incidence on these respective variety planted in monoculture was 9.8%, 8,8%, 4.3%, and 8.5%. Then, the optimum of N. virescens population per clump on rice variety with intercropping in the same time of observation was 4.8, 2.3, 1.5, and 4, and on variety with monoculture was 6.5, 4.5, 3.3, and 4,5, respectively. Moreover, the population of insect predators tended to be higher on variety with intercropping than on rice variety with monoculture. These data indicated that rice planted with variety intercropping was related to the reduction of tungro incidence and its vector and also the increase of insect predators. Therefore, the intercropping of variety could used as one of control method against rice pests and diseases.