Herbicide mixture, Herbicide resistance, Metribuzin, Phalaris minor, Wheat

Farmers’ participatory field trials were conducted at village Kheri Raiwali in Kaithal district of Haryana during winter seasons of 2011-12 and 2012-13 to evaluate the bio-efficacy of post-emergence herbicides, their mixtures and sequential application for the control of the resistant littleseed canarygrass (Phalaris minor) and other weeds in wheat. Application of clodinafop 60 g/ha, fenoxaprop 120 g/ha and sulfosulfuron 25 g/ha at 35 days after sowing (DAS) did not provide satisfactory control of P. minor; however, mesosulfuron + iodosulfuron 14.4 g/ha provided better control (85-90%). Pinoxaden 50 g/ha resulted in 80% control of P. minor during first year but it provided only 55% control during second year. Ready-mix combination of metribuzin with fenoxaprop and clodinafop significantly improved the control of P. minor and broad-leaf weeds as compared to alone application of fenoxaprop and clodinafop. Maximum weed control efficiency (WCE) and highest grain yield (5.2 t/ha) was recorded with the application of sulfosulfuron + metsulfuron 32 g/ha during 2011-12, which was statistically at par with mesosulfuron + iodosulfuron and clodinafop + metribuzin; whereas during the second year, sulfosulfuron + metsulfuron 40 g/ha resulted in highest grain yield. Sequential application of sulfosulfuron + metsulfuron 32 g/ha at 25 DAS before irrigation fb sulfosulfuron + metsulfuron 32 g/ha at 40 DAS (after first irrigation) registered 97% WCE but its continuous adoption may lead to rapid development of resistance. The study indicates the need of new post-emergence herbicide with different mechanism of action (MOA), which can be integrated with non-chemical weed control strategies.