optimizing the efficacy of clodinafop-propargyl to control littleseed canarygrass (phalaris minor retz.) with the vegetable oils

in order to comparing influence of ten vegetable oils for optimizing clodinafop-propargyl efficacy, a greenhouse experiment of dose-response including 0, 8, 16, 32, 48, and 64 g a.i. ha-1 of clodinafop-propargyl at eleven level of without vegetable oil and with vegetable oils of sunflower, soybean, canola, turnip, cotton, sesame, bitter almond, sweet almond, castor and olive in control of littleseed canarygrass (phalaris minor retz.) with four replications was done. results showed that all of the vegetable oils significantly reduced the surface tension and subsequently improved the efficiency of herbicide to control littleseed canarygrass. the performance of the vegetable oils were sunflower > rapeseed > soybean > cotton > olive > canola > bitter almond > sesame > castor > sweet almond according to dry weight and rapeseed > sunflower > soybean > cotton > bitter almond > olive > canola > sesame > castor > sweet almond according to fresh weight. the overall results showed that with increasing content of saturated fatty acids of vegetable oils, decreasing power for surface tension decreased but herbicide performance increased. accordingly, therefore, an increase in the penetration of a.i. by vegetable oils via softening or disrupting of the cuticular waxes is a more effective factor than a decrease in the surface tension of spray droplets.