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A series of field Experiments were conducted on sandy loam soil with 51.4% sand, 36% silt, 12.6% clay, .68% organic matter and a pH of 8.1 at Cereal Crops Research Institute Pirsabak, Nowshera during 1990-1993 to study weed control methods under different crop density and sowing time r regimes in relation to yield of wheat crop. The treatments comprised three planting dates, viz; October 15, November l5 and December 15, three seeding rates viz; 50, 100 and 150 kg/ha and three weed control methods Viz No weeding, hand weeding and chemical weeding. Data were recorded on days to heading, days to maturity, plant height, spikes per square meter, grains per spike, 1000 grain weight, grain yield, weeds density, dry weeds biomass and straw yield respectively. Economics were calculated to determine the net benefits and marginal rate of return in percent of different treatments. The results indicated that days to heading, days to maturity and plant height decreased with delay in planting from November 15. The crop planted on November 15, produced greater number of spikes per square meter, more grains per spike, heavier grains and the highest grain and straw yield as compared to late and early planting. However late planting adversely affected grain yield and grain yield components. The highest weeds density and dry weed biomass were observed from October l5, planting. The weed population and dry weed biomass were less in December 15, planting as compared to early and mid planting of October 15 and November High seeding rate (150 kg/ha) took more days to -heading and days to maturity than 100 kg and 50 kg/ha. Plant height, spikes per square and straw yield were also maximum in 150 kg seeding rate. The 100 kg seeding rate/ha was better in producing highest grains per spike, 1000 grain weight and grain yield and it was followed by 150 kg seeding rate/ha. The maximum weeds density and dry weed biomass were recorded in those plots where the seeding rate was 50 kg/ha, while the minimum weeds density and dry weed biomass were in those plots, where the seeding rate was 150 kg/ha. The weeds control methods affected all the parameters positively. Maximum days to heading, days to maturity, plant height, Number of spikes/m2, grains per spike, 1000 grain weight, grain yield and straw yield were obtained ill those plots, where the weeds were controlled by herbicide. Dry weed biomass and weeds density per sq. meter were less in those plots, where the herbicide was used The highest net benefit and marginal rate of return was obtained when the wheat crop was planted in mid-November at seeding rate of 100 kg/ha and chemically weeded. The mechanical weeding was also 'better because marginal rate of return and net benefit ratio was quite justified for weeds control vs no weeds control.

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