Investigation efficacy of some graminicides in control of resistant and susceptible ryegrass biotypes (Lolium rigidium L.) to acetyl-CoA carboxylase inhibiting herbicides

In order to determine efficacy of some registered graminicides in control of resistant and susceptible ryegrass biotypes, two greenhouse trials were conducted at weed research department of Iranian plant protection research institute during 2007. Experimental design was completely randomized design with eight replications. The susceptible and resistant biotypes were treated by 19 herbicides included 10 acetyl-CoA carboxylase inhibiting herbicides, 6 acetolactate synthase inhibiting herbicides and 3 herbicides with different mode of action. Ryegrass biotypes were treated in 4 leaves stage by recommended dose of herbicide. Number of survived plant per pot, fresh and dry weight (30 days after herbicide application) and EWRC visual rating (15 and 30 days after herbicide application) were measured. Results showed that clodinofop-propargil cycloxidim, pinoxadon (at 450 and 600 ml.ha-1), iodosolforon + mesosolforon (chovalieh), iodosolforon + mesosolforon (Atlantis) and isoprotron + diflofnikan had very good to optimum control of susceptible biotype. Results also indicated that cytoxidim, iodosolforon + mesosolforon (Atlantis), pinoxadon at 600 ml.ha-1 and isoprotron + diflofnikan had very good to optimum control of resistant biotype. Diclofopmethyl, cytoxidim and clorosolforon had less optimum control of susceptible biotype. Finally, iodosolforon + mesosolforon (Atlantis), isoprotron + diflofnikan and pinoxadon at 600 ml/ha were advised to control resistant biotype to acetyl-CoA carboxylase inhibiting herbicides in wheat fields. It is also recommended to consider crop rotation as well as herbicide rotation to use these herbicides continuously.