BACKGROUND: Leptochloa chinensis (L.) Nees is a troublesome weed across China in rice fields, and a suspected L. chinensis resistant population (R) that has survived the recommended field dose of cyhalofop-butyl was collected in a rice field of Hunan Province, China. In this study, we aimed to determine the acetyl-CoA carboxylase-inhibiting herbicide resistance profile of this R population and to investigate its mechanisms of resistance to cyhalofop-butyl. RESULTS: Compared with the susceptible population (S), the R population was confirmed to be 18.9-, 3.2-, 4.1-, 3.6- and 5.8- fold resistant...