This research aimed to verify the occurrence of resistant biotypes of crab-grass (Digitaria ciliaris) to Acetyl-Co-A Carboxylase (ACCase)-inhibiting herbicides through dose-response curves, as well as to establish the degree of cross resistance to the CHD and APP herbicides of these biotypes. The experiment was conducted in the greenhouse and tested four suspected resistant populations (R1, R2, R3 e R4) and a susceptible one (S). The experimental design adopted was randomized complete blocks with four replications, and the treatments were the result of a factorial interaction among five populations, three herbicides (fluazifop-p-butyl, sethoxydim and tepraloxydim), and eight rates (0C, 0.06C, 0.125C, 0.5C, 1C, 2C, 4C and 10C), where C is the recommended rate for each product. Control percentage was analyzed at 28 days after application (DAA). From the results obtained it could be concluded that the populations R1, R2, R3 and R4 were found to be resistant biotypes to ACCase-inhibiting herbicides with different levels of cross-resistance to the herbicides with this action mechanism.
cross-resistance; ACCase; biotypes
