Multiple resistance of silky windgrass to acetolactate synthase- and acetyl-CoA synthase–inhibiting herbicides

Abstract Field and pot experiments were conducted in Greece to study the occurrence of resistance silky windgrass acetolactate synthase (ALS)- acetyl-CoA (ACCase)-inhibiting herbicides. Twenty-four populations examined whole-plant response experiments. High levels field-evolved chlorsulfuron (0% 28% control terms fresh weight reduction) with recommended field rates confirmed most populations. However, other ALS inhibitors, such as pyroxsulam a premix mesosulfuron-methyl iodosulfuron, provided adequate (76% 100% populations, except eight that found be cross-resistant all ALS-inhibiting herbicides tested (i.e., chlorsulfuron, commercial mixture plus pyroxsulam). Conversely, controlled effectively (90% ACCase inhibitors cycloxydim, clethodim, pinoxaden, but five also resistant clodinafop-propargyl (10% 68% reduction). The gene sequencing cross-resistance revealed point mutation at Pro-197 position, causing amino acid substitution by Ser or Thr enzyme. Overall, selecting agents multiple ALS- ACCase-inhibiting As available postemergence-applied chemistries/modes action registered for grass weed cereals are rather limited, adopting integrated management practices implementing proactive reactive measures delay evolution is essential.