Integrated Control of Rice Pests with Minimum Use of Agrochemicals in West Bengal, India.

We have been trying to develop a minimum routine plant protection schedule coupled with supervisory exigency measures based on critical levels of pest incidence in rice. During 1980 wet season in the present experiment there was very severe incidence of rice tungro virus because of widespread epidemics of the disease, and there were no serious incidence of any pest in 1975 wet as well as in the 1980–81 dry season tinder report. In the seasons when there were no serious pests, there were significant differences between different levels of plant protection, indicating the success of minimum routine schedule coupled with supervisory exigency measures to combat moderate levels of pest incidence. In the seasons when one or the other pest became very severe sometimes maximum protection offered better control than other when the coritrol measure included appeared to be adequate, while there were no significant differences between other levels of protection. In other cases no significant difference could be found in which the control measure included did not appear to be adequate for the particular pest. Moreover, during years of heavy and frequeny rains spray programmes were nearly completely thwarted. Further, uptake of prmary nutrients as well as foliar feeding of micronutrients were significantly better in dry seasons as in 1980–81, and in wet seasons with optimum and well-distributed rains as noted previously. It was also noted that multiple effects of diseases and pests none of which independently crossed the critical thereshold: levels could be significantly protected, although the measures were not economic.