Weeds are one of the major constraints limiting haricot bean productivity and production. Field experiments were conducted on the effect of weed managements on weeds and grain yield of haricot bean (Phaseolus Vulgaris L.) at Melkassa Agricultural Research Center from 2011 - 2013. The objective was to determine the effect of weed managements, varieties and their interaction on weeds and grain yield. The experiment was laid out split plot arrangement using randomized complete block design with three replications. Treatments were s-metolachlor at the rate of 0.96 kg ha-1, glyphosate at the rate of 1.08 kg ha-1, integration of each herbicide with hand-weeding at 45 days
after sowing, twice hand-weeding at 25 and 45 day after sowing and un-weeded check. Nicandra physalodes, Xanthium strumarium and Argemone ochroleuca were the dominant weed species. Weed density and dry matter weight were significantly influenced by weed managements. The highest (129.50 m-2) and the lowest (69.50 m-2) weed density were recorded from weedy check and integration of s-metolachlor at the rate of 0.96 kg ha-1 and hand-weeding. Comparison of weed managements showed that the lowest (114.72 gm-2) weed dry matter was recorded from application
of s-metolachlor with hand-weeding at 45 days after sowing while the highest (349.50 gm-2) weed dry matter was obtained from weedy check. The highest (67.17%) weed control efficiency was obtained from integrated use of s-metolachlor with supplementary hand-weeding. The effect of variety, weed managements and their interaction showed significant difference (p<0.05) on yield components and grain yield. The highest yield components and grain yield were obtained from smetolachlorplus hand-weeding while the lowest grain yield was obtained from weedy check. The relationship between weed dry matter and grain yield showed significant negative correlation. Interaction effects of years, variety and managements showed non-significant (p < 0.05) difference for all parameters. The effect due to varieties and the interaction of variety and management did not show significant difference on weed density and dry matter though yield components and grain yield were significantly affected. This might be due to similar plant architecture or leaf canopy closure but difference in yielding potential of the test varieties. Hence, similar weed control practices can be recommended for both varieties.
