Isobolographic Analysis for Additive, Synergism and Antagonism in Binary Mixture of Mesosulfuron + Iodosulfuron and Clodinafop-propargyl and Optimizing them with Citowett and Frigate Surfactants on Wild Oat (Avena ludoviciana)

To study the effect of mesosulfuron + iodosulfuron and clodinafop and also their mixtures with Citowett and Frigate surfactants، three greenhouse experiments were conducted on wild oat (Avena ludoviciana L.) as dose-response arrangements in completely randomized design with four replications for each treatment. Treatments included mesosulfuron + iodosulfuron alone at doses of 0، 2. 4، 6، 12، 18 and 24 g ai ha-1، clodinafop alone at doses of 0، 6. 4، 16، 32، 48 and 64 g ai ha-1 and six mixture ratios of doses of the two herbicides including 100:0%،75:25%، 50:50%، 25:75%، 10:90% and 0:100% with and without the surfactants of Citowett and Frigate at 0. 2% (v/v). Herbicide performance was enhanced by all surfactants against wild oat. Pure mixture of herbicides with each other (without surfactants) followed CA model and showed additive effects. Mixtures with Citowett or Frigate surfactants followed Hewlett model and showed synergism on wild oat. Pure mixtures of two the herbicides showed lowest effects on wild oat compared to their mixtures with Citowett، Frigate surfactants. Mesosulfuron + iodosulfuron and clodinafop mixed with Citowett surfactant showed highest effect and Frigate surfactant showed lowest effect on wild oat.