Directorate of Rice Research, Rajendranagar, Hyderabad-500030, Andhra Pradesh, India.
In field studies, neem formulations viz., Neemgold and Nimbecidine, which are oil based with low azadirachtin content (300 ppm) prevented the resurgence of rice brown planthopper (BPH) caused by a synthetic pyrethroid, deltamethrin (25 g a.i./ha). These oil based neem formulations were used at recommended concentration of 4% (12 ppm of azadirachtin) as tank mixing before spraying or as alternate applications with deltamethrin. Neem Azal T/S having 10, 000 ppm azadirachtin at 0.5% concentration (50 ppm of azadirachtin) could not prevent resurgence of BPH caused by deltamethrin in similar applications. The constituents other than azadirachtin present in oil based neem formulations appeared to be responsible for preventing resurgence of BPH caused by deltamethrin under field conditions in rice.
