Field experiments were conducted consecutively over a period of two years at Agricultural College & Research Institute Farm, Madurai to study the response of blackgram to methods of sowing and post-emergence herbicides under rice fallow conditions during rabi season. The dominant weed flora observed on sandy clay loam soils of rice fallow blackgram were Echinochloa colonum, Echinochloa crusgalli, Panicum repens, Cyperus rotundus, Sphaeranthus indicus and Eclipta alba. Grasses were found to be dominant followed by broad leaved weeds and sedges. Among different methods of sowing, dibbling the seeds three days after pre-sowing application of paraquat @ 0.5 kg ha-1 recorded significantly lower values of grass weed density, grass weed dry matter production and higher value of weed control efficiency in both years of study and hence better growth and reproductive parameters were obtained under the same treatment. Application of fenoxaprop-p-ethyl @ 75 g ha-1 or cyhalofop butyl @ 100 g ha-1 on 15 DAS significantly reduced the density and dry weight of dominant grassy weeds over the other treatments. The extent of control of dominant grass weeds was 85.41 % with fenoxaprop-p-ethyl in 2004 and 85.76 % with cyhalofop butyl in 2005 at 30 DAS. The interaction effect was also found to be significant. The maximum seed yield and yield components were recorded with dibbling the seeds three days after pre-sowing application of paraquat @ 0.5 kg ha-1 with post emergence application of either fenoxaprop-p-ethyl @ 75 g ha-1 or cyhalofop butyl @ 100 g ha-1.