Multiple Herbicide Resistance in Phalaris Minor Retz. in Haryana, India

A screen house study was conducted at CCS Haryana Agricultural University, Hisar during (winter) Rabi 2018–19 and 2019–20 to evaluate the resistance in various populations of Phalaris minor Retz. in Haryana against clodinafop and also to evaluate the efficacy of alternate herbicides against the herbicide resistant weed populations. The alternate herbicides were sulfosulfuron, pinoxaden and mesosulfuron + iodosulfuron (ready-mix). The seeds of P. minor were sown in pots and 20 plants per pot were maintained. All the herbicides were applied at 2–3 leaf stage of P. minor i.e. about 25–27 days after sowing. Herbicides were applied with graded doses viz. 1/2X, X (recommended dose), 2X and 4X dose. The variation in the percentage decrease in the biomass was observed amongst P. minor populations with the application of different herbicides under their doses. Clodinafop (60 g/ha) and mesosulfuron + iodosulfuron (14.4 g/ha) provides <30% decrease in the biomass of Sitamai, Karnal population at the recommended dose. The poor efficacy of clodinafop at recommended dose was observed in most of the P. minor populations expect those populations of Hindwan, Hisar (susceptible population) and Laloda, Fatehabad. An increase in the reduction of biomass was observed with an increase in the dose to 2X and 4X but at 2X dose of clodinafop, Kalwan, Jind population showed minimum decrease in the biomass during both years of the study. There was decrease in the efficacy of sulfosulfuron during 2nd year of study particularly in Rasidan, Jind population. The reduced efficacy (<70%) against clodinafop, sulfosulfuron, mesosulfuron + iodosulfuron and pinoxaden was observed in Sitamai, Kalwan, Ramba and Ramba populations of P. minor, respectively.