Control of Complex Weed Flora of Dry-seeded Rice (Oryza sativa L.) with Pre- and Post-emergence Herbicides

To tackle the serious problems of weeds in dry direct-seeded rice (DSR), a field experiment was conducted on loamy sand soil at Ludhiana, Punjab during 2006 and 2007 with an objective to identify effective herbicides for the control of complex weed flora of DSR. It is difficult to raise weed free DSR with the application of only one herbicide. Integration of pre-emergence application of pendimethalin 0.75 kg/hafollowed by post-emergence (30 DAS) application of bispyribac 25 g/ha or azimsulfuron 20 g/ha or 2,4-D 500 g/ha resulted in effective weed control and higher rice grain yields. Pendimethalin pre-emergence application provided effective control of non-predominant paddy weeds, whereas bispyribac controlled all typical predominant paddy weeds including Echinochloa colona and all Cyperus species. Azimsulfuron or 2, 4-D was effective against all Cyperus spp. and broad-leaved weeds. Integration of pre-emergence application of pendimethalin 0.75 kg/ha with post-emergence application of bispyribac 25 g/ha resulted in 372% increase in rice grain yield as compared to unweeded control.