Pre- and post-emergence herbicide sequences for management of multiple herbicide-resistant littleseed canary grass in wheat

Littleseed canary grass (Phalaris minor) is the ubiquitous and pernicious grass weed of wheat in rice-wheat cropping system in north-western Indo- Gangetic plains of India. A field experiment was conducted during Rabi 2014–15 and 201516 in a farmers field infested with P. minor having history of poor control with acetyl-CoA-carboxylase inhibitors in village Nangla, district Fatehabad, Haryana, India with an objective to compare pre-emergence only, postemergence only and pre-emergence followed by post-emergence herbicide treatments for control of P. minor in wheat. The sequential application of preemergence pendimethalin 1.5 kg/ha fb post-emergence pinoxaden + metsulfuron 64 g/ha and pre-emergence pendimethalin 1.5 kg/ha fb post-emergence mesosulfuron + iodosulfuron 14.4 g/ha provided 88–93% control of P. minor compared to alone pre- and post-emergence herbicide treatments. Grain yield of wheat increased significantly by 69–78% with pre-emergence pendimethalin 1.5 kg/ha fb post-emergence pinoxaden + metsulfuron 64 g/ha or pre-emergence pendimethalin 1.5 kg/ha fb post-emergence mesosulfuron + iodosulfuron 14.4 g/ha due to significant increase in yield attributes. Alone pre- or post-emergence herbicides provided ineffective control of P. minor (44–66%) and recorded lower grain yield. It was concluded that herbicide sequences having both pre- and postemergence herbicides would be better option as compared to their alone applications in order to manage resistant populations of P minor in wheat.