Effect of herbicides with or without paddy weeder on weeds in transplanted summer rice (Oryza sativa)

A field investigation was carried out during the winter (rabi) season of 2003–04 and 2004–05 at Jorhat, with herbicides, viz. butachlor, oxadiargyl, pyrazosulfuron ethyl, pretilachlor, chlorimuron + metsulfuron methyl, fenoxaprop-p-ethyl applied alone or followed by paddy weeder to test their efficiency in controlling weeds in transplanted summer rice. All the weed-control treatments increased the grain yield of rice significantly over unweeded check and decreased the population and dry weight of weeds significantly. Uncontrolled growth of weeds caused 49% reduction in crop yield. Treatment of pretilachlor 0.75 kg/ha (pre-emergence) + paddy weeder, resulted in the highest grain yield, maximum weed-control efficiency (88%) and monetary returns (Rs 8,300/ha). Herbicides alone were inferior to their use with paddy weeder.