effect of pre- and post-emergence herbicides and their combination on weed control and yield of safflower (carthamus tinctorius l.)

in 2007, an experiment was conducted at the farm of the college of agriculture, isfahan university of technology, in najaf abad (lavark), to study the effects of two pre-emergence herbicides (trifluralin and ethalfluralin) when combined with the three post-emergence herbicides setoxydim, cycloxydim and haloxyfop and the two post-emergence herbicides desmedipham and phenmedipham on weeds and the growth characteristics and yield of safflower. in this study, ten herbicide treatments (trifluralin, ethaltrifluralin, desmedipham, phenmedipham, trifluralin + setoxydim, ethaltrifluralin + setoxydim, trifluralin + cycloxydim, ethaltrifluralin + cycloxydim trifluralin + haloxyfop, ethaltrifluralin + haloxyfop) along with the un-weeded and hand weeded controls were evaluated using a randomized complete block design with three replications. desmedipham and phenmedipham (the post-emergence herbicides) significantly reduced the height, dry matter, yield and yield components of the safflower compared to the hand weeded and other herbicide treatments. weeds compete with the safflower, especially in the early growing season, reduced yield components and yield in the un-weeded control (1028.1 kg ha-1) compared to the hand weeded control (1629.6 kg ha-1). all pre-emergence treatments increased the yield and yield components of safflower as a consequence of decreased competition with the crop. a higher safflower yield was obtained with ethaltrifluralin (1571.2 kg ha-1) and trifluralin (1547.8 kg ha-1) treatments. thus, ethaltrifluralin and trifluralin might be recommended for weed control with no injurious effect on the safflower under conditions similar to this experiment.