Management of herbicide resistant Phalaris minor in wheat

Field experiment was conducted at CCS Haryana Agricultural University during Rabi 206-17 and 2017–18 to evaluate bio-efficacy of different herbicides and their combination against cross resistant P. minor in wheat, and to study the phytotoxic effects on the crop, if any. The treatments included application preemergence herbicides pendimethalin 1500 g/ha and its mixture with metribuzin 175 g/ha alone, pendimethalin + pyroxasulfone Tank mix (TM) at 1500 + 102 g/ha alone and their sequential application with post-emergence herbicides application (PoE) of mesosulfuron + iodosulfuron ready mix (RM) 14.4 g/ha and pinoxaden 60 g/ha along with weedy check treatment. The minimum density of P minor, weed biomass and the highest wheat grain yield was observed with pendimethalin + pyroxasulfone TM fb mesosulfuron+ iodosulfuron RM (1500 + 102 fb 14.4 g/ha). All the herbicides significantly reduced the weed biomass as compared with the control but maximum reduction in the weed biomass was achieved with pendimethalin + pyroxasulfone TM fb mesosulfuron+ iodosulfuron RM. Pinoxaden at 60 g/ha did not control Rumex dentatus and Chenopodium album. Only pre-emergence application of metribuzin, pendimethalin + metribuzin (before sowing), pinoxaden + metribuzin TM caused toxicity of up to 5% at 10 days after treatment (DAT). The wheat recovered from toxicity by 20 DAT without any yield penalty. On-farm demonstrations of pyroxasulfone at 127.5 g/ha PE in Haryana revealed 88.3 % control of multiple herbicide resistant P. minor. Its integration with pendimethalin at 1.5 kg/ha (PE) and post-emergence herbicides at 35 DAS has improved control of P minor to 92.1%.