Using Isobolographic Analysis for the Evaluation of Additive, Synergism and Antagonism Effects in Binary Mixture of Glyphosate and Clopyralid on Acroptylon repense Control

Document Type : Research Article



Mixing herbicides is an essential for weed management strategy of reduce herbicide using and reducing the risk of side-effects and costs of herbicides. Therefore, to study the effect of clopyralid and glyphosate and their mixtures on Acroptylon repense control, a field trial was conducted as split plot based on a completely randomized block design with 35 treatments (as dose-response arrangement) and three replications in Golmakan, Khorasan Razavi, Iran in 2007. Five mixtures ratios were as main plots and doses of the ratios were as sub-plots. Treatments included five mixture ratios (100:0%, 75:25%, 50:50%, 25:75% and 0:100%) of glyphosate and clopyralide. Glyphosate alone at doses of 0 , 1 , 2 , 3 , 5 , 7 and 10 1 ha-1, clopyralid alone at doses of 0, 100, 200 , 300 , 500 , 700 and 1000 ml ha-1, plus mixtures ratios of the two herbicides doses as 75%:25%, 50%:50% and 25%:75%, respectively. Herbicides were sprayed by Matabi sprayer with cone nozzle and by considering 400 l ha-1 herbicide solution. Mixture of herbicides followed CA model and showed additive effects on Acroptiylon repens. Clopyralid at doses of 700 and 1000 ml ha-1 and glyphosate at doses of 7 and 10 l ha-1 showed complete control of Acroptylon repense. By increasing the clopyralid ratio in mixtures (75% clopyralid + 25% glyphosate) the control of Acroptylon repense remarkably increased in comparison with other mixing treatments.