A field experiment consisted of four intercropping systems, viz. winter maize (sole), potato (sole), winter maize + potato (additive series) and winter maize + potato (replacement series) and six sub-plot treatments comprised of weedy check, weed free, alachlor as pre-emergence at1.5 kg/ha, atrazine as pre-emergence at 0.5 kg/ha, early post-emergence alachlor at 2.0 kg/ha and atrazine as post-emergence at 0.75 kg/ha was laid out in split plot design with three replications. Results revealed that Medicago sativa, Anagallis arvensis and Cyperus rotundus recorded highest relative weed density and dry weed weight. The values of weed smothering efficiency were numerically higher in additive as compared to replacement treatment. Maximum yield loss was in weedy check in comparison to weed-free plots. Pre-emergence application of atrazine 0.5 kg/ha resulted in significantly lower dry-matter accumulation of all the weed species and highest weed-control efficiency which lead to significantly higher crop productivity.