Echinochloa colona, Cyperus difformis, Eelipta alba and Marsilea quadrifolia were the major weed species in the irrigated low land rice fields. Continuous submergence followed by irrigating one day, after disappearance of ponded water resultec in lesser growth and development of weeds. Butachlor (1.25 kg/ha) followed by one hand weeding at 25 d.a.t. and hand weeeding twice at 25 and 45 d.a.t. effectively controlled the weeds resulting in higher grain yield over unweeded check. Azolla dual cropping as found to suppress the weed growth and check N removal by weeds and increase the grain yield over uninoculated plots.
