An on-farm trial was conducted at farmers’ fields in the Hassan district of Karnataka during Rabi seasons of 2006-07 and 2007-08 to find out the effective and economical integrated weed control method in potato. Amaranthus viridis, Chenopodium album, C. murale and Poa annua were the major weed species in potato field. Mulch (water hyacinth) along with application of oxadiazon (0.75 kg/ha) at seven days after planting (DAP) was found most effective in controlling weed population (94 to 95%) upto 30 days of planting than that employed by only mulch (45 to 53%). The weeds were found to reduce tuber yield to the extent of 43%. Among the weed control treatments, minimum nutrient uptake by weeds and highest tuber yield were recorded with mulching+oxadiazon (0.75 kg/ha) spray at 7 DAP+one hand weeding at 25 DAP, and these were at par with weed free check. The highest net returns of Rs. 74563 and 122859/ha and maximum benefit : cost ratio of 2.75 and 3.27 were noted in mulching with water hyacinth+herbicide application at 7 DAP+one hand weeding at 25 DAP in 2006-07 and 2007-08, respectively.