The poor control of Panicum dichotomiflorum, Aeschynomene indica and Ageratum conyzoides by imazethapyr during 1990–91 increased their population during 1991–92. Pre-emergence application of imazethapyr 200 g/ha reduced the population of all the weeds of soybean except Aeschynomene indica and Ageratum conyzoides. While the population of Panicum dichotomiflorum was not reduced by its pre-emergence application. the population of Echinochloa spp. and Aeschynomene indica were reduced partially by its pre-plant incorporation. The population of Cyperus spp. was reuced effectively even by its lowest dose (50 g/ha). Residues of imazethapyr 200 g/ha being at par with 150 g/ha (at all the times of application) reduced the population of all the weed species except Vicia sativa significantly in wheat+pea. Isoproturon application in wheat+pea cropping system did not control Lolium temulentum effectively and increased its population by 11.6 per cent during second year.
