Impact of weeds and methods of weed control on the incidence of stem borers (Scirpophaga incertulas Wlk., Chilo suppressalis Wlk. and Sesamia inferens Wlk.) in deep water rice

Amongst the different methods of weed control in deep water rice, viz., one hand weeding, two hand weedings, butachlore 15 kg a.i./ha alone, and butachlore 1.0 kg a.i./ha + one hand weeding did not show significant effect in reducing the damage by stem borers, viz., Scirpophaga, incertulas Wlk., Chilo suppressalis Wlk. and Sesamia inferens Wlk., and these were comparable with weed free check and non-weeded check at seedling stage of the crop. However, highest damage was recorded in non-weeded check at panicle initiation stage (19.33%) and at maturity (46.00%). The treatment differences were wider at the maturity of crop. The lowest infestation (22.00%) was recorded in weed free check, followed by butachlore (1.0 kg a.i./ha) at 4–6 days after rice emergence (DARE) + one hand weeding at 25–30 DARE i.e., 25.00 per cent. The extent of damage at different growth stages of the crop, viz., seedling, panicle initiation and maturity, revealed significant correlation.