Determining critical period for weeds control in sage (Salvia officinalis L.)

Abstract. The critical period for weeds control in sage was determined in an experiment based on a Randomized Complete Block Design with three replications and five treatments in Ardabil in 2010-2011. The treatments included weeds interference and weeds control with the intervals of 20 days (0, 20, 40, 60, and 80 days after sowing). It was found that among weeds interference treatments, the highest weeds population was observed in the treatment of weeds interference until 40 days and among weeds control treatments, the highest weeds population was in the treatment of weeds control until 20 days as the duration of weeds interference was increased, their density was decreased because of self-thinning. Critical period for weeds control in sage was found to be 76, 60 and 53 days for acceptable yield losses of 5, 10 and 15%, respectively