Greenhouse assay to investigate resistance of littleseed canary grass (Phalaris minor) to aryloxyphenoxy propionate herbicides

In order to evaluate resistance of Phalaris minor biotypes, sampled from wheat fields of Fars and Golestan provinces, to ACCase inhibiting herbicides, a dose-response study was conducted under controlled conditions in greenhouse of Ferdwosi University of Mashhad. The results indicated that AR, SR3, MR4, FR2, FR4, and FR8 populations of Fars and GR2-1 biotype from Golestan have been resistant to diclofop-methlyl. Different levels of resistance maybe are because of involving different mechanisms in studied populations. AR, SR3, and MR4 showed a cross-resistance to the applied herbicides. These biotypes indicated a 5- to 11-fold and a 7- to 8-fold increase in resistance to diclofop-methlyl and clodinafop-propargyl, respectively compared with the susceptible biotype. Among these biotypes, SR3 showed the highest resistance to both herbicides.