Post-emergence herbicides for the control of resistant littleseed canarygrass in 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.