A strategy of chemical control of Apera spica-venti L. resistant to sulfonylureas traced on the molecular level

Th ree populations of silky bent grass (Apera spica-venti L.) were tested – one that is susceptible and two that are resistant to sulfonylureas. Th is study assessed the effi cacy of control by diff erent herbicides in a pot experiment and estimated the molecular status of resistance to sulfonylureas in analysed populations and its eff ect on the effi cacy of diff erent chemical treatments. Th e three most eff ective herbicide rotation schemes were: 1) chlorsulfuron + isoproturon, ethametsulfuron + metazachlor + quinmerac, chlorsulfuron + isoproturon; 2) prosulfocarb + difl ufenican, ethametsulfuron + quizalofop-p-ethyl, prosulfocarb + diflufenican; 3) difl ufenican + fl ufenacet, quizalofop-p-ethyl, difl ufenican + fl ufenacet. In most cases it was more diffi cult to destroy 100% of the resistant population from Modgarby where the majority of plants had no mutation in the als gene. In the resistant population from Babin there were signifi cantly more individuals with mutation in the als gene, therefore exhibiting target-site resistance.