HERBICIDE RESISTANCE IN ANNUAL RYEGRASS (Lolium rigidum Gaud.) POPULATIONS IN WHEAT FIELDS OF FIROOZABAD IRAN

An experiment was conducted to detect herbicide resistance in ryegrass (Lolium rigidum Gaud.) populations infesting wheat (Triticum aestivum L.) fields across the Firoozabad city, Fars Province, during 2008-09. Ryegrass population in each agronomic zone was sprayed with several herbicides having different modes of action using upper recommended dose. Some of these ryegrass populations were found to be resistant to the ACCase–inhibitor herbicides: diclofop-methyl 60% and clodinafop-propargyl 50%. These populations were completely susceptible to herbicides with other modes of action like ALS-inhibitors, mesosulfuron+iodosulfuron, tubuline formation inhibitors, trifluralin and phenylpyrazolin, and pinoxaden. We did not detect any Point mutation 2078-Gly in ryegrass populations through the molecular dCAPS approach.