Joint action of sugar beet selective herbicides in Portulaca oleracea L. and Chenopodium album L.

The successful application of herbicides for selective and economic control of weeds without damage to both the environment and crop is one of the important achievements in modern agriculture. In order to predict the additive, synergistic and orthogonal effects of binary mixtures of desmedipham+ phenmedipham+ ethofumesate, chloridazon and clopyralid herbicides based on Additive Dose Model (ADM), two greenhouse experiments were conducted in completely randomized design with 105 treatments and three replications for Chenopodium album L. and Portulaca oleracea L. weeds in the greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran in 2013. Experimental treatments consisted of seven herbicides with five mixing ratios of 0:100, 25:75, 50: 50, 75:25, 100:0 and three control treatments for each of the herbicide ratio. Results showed that the binary mixture of herbicides has a strong dependence on various factors such as weed species so that each species showed different response with different morphological and physiological characteristics. Accordingly, the mixture of desmedipham+ phenmedipham+ ethofumesate and clopyralid based on ADM model was synergistic. Also desmedipham+ phenmedipham+ ethofumesate, and chloridazon herbicides mixture had synergistic effect on weed control based on ADM model. In contrast, chloridazon and clopyralid herbicides mixture had additive effect on Portulaca oleracea L. and synergistic effect on Chenopodium album L. control.