Timely sowing and adoption of proper methods of weed control are important factors in increasing lentil yield. In order to study the effect of sowing date, single or integrated application of herbicides, an experiment in completely randomized block design in a split plot arrangement was performed with four replications at the research farm of Tehran University, Karaj (Iran) during 2001-2002 growing season. Treatments were comprised of two dates of either winter or spring sowing, as whole plots, along with eleven weeds control procedures as subplots. Weed control treatments included a pre-emergence application of cyanazin (1 kg. a.i. /ha), post-emergence application of pyridate (1.2 kg. a.i./ ha) and oxyflourfen (480 gr. a.i./ha); different combinations of a pre-plant application of trifluralin (960 gr. a.i. / ha), pendimethalin (1.32 kg. a.i. /ha) each with post–emergence application of pyridate (1.2 kg. a.i. /ha) and oxyflourfen (480 gr. a.i. /ha) plus one handweeding ; and finally a weed free as well as an infested plot as checks. The results indicated that lentil seed yield and yield components were significantly affected by sowing date as well as weed control treatments (p<0.01). In winter sowing, seed yield and other components, except 1000 seed weight, were significantly higher as compared to spring sowing. The integrated treatments of pendimethalin + pyridate, pendimethalin + one handweeding, and trifluralin + one handweeding in comparison with check (weed infested plot) lead to the best results, indicating that they are the most proper treatments for weed control in lentil crops, under coditions similar to those in this experiment.
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