Wheat growth and physiological response and management of herbicide resistant Phalaris minor Retz. as affected by selective herbicides

Abstract

Weeds are a major constraint of wheat productivity improvement in India. Among the major weeds, Phalaris minor Retz. is the most problematic weed that mimics wheat. Herbicides are mostly used by farmers to manage weeds in wheat and dependency on single herbicide or herbicides with same mode of action resulted in the development of multiple herbicide-resistance in P. minor. A field study was conducted at CCS Haryana Agricultural University, Hisar during 2016-17 and 2019-20 with an objective to study the growth and physiological response of wheat and management of herbicideresistant P. minor with selective herbicides in wheat. The sequential application of tank-mix (TM) pre-emergence application (PE) of pendimethalin + pyroxasulfone (1500 + 102 g/ha) or pendimethalin + metribuzin (1000 + 175 g/ha) followed by post-emergence application (PoE) of pinoxaden 60 g/ha or mesosulfuron + iodosulfuron 14.4 g/ha resulted in complete control of herbicide-resistant P. minor and other broad-leaved weeds (BLW). The better control of weeds resulted in higher wheat leaf area index (LAI) and crop growth rate (CGR) with 43-46% higher wheat grain yield over the weedy check. However, 0-9% visual toxicity on the crop was observed in metribuzin-associated treatments, which was nullified with the advancement of crop stage. The maximum marginal benefit was observed in weed-free check (39,192 ₹/ha) closely followed by pendimethalin + pyroxasulfone (TM) PE fb mesosulfuron + iodosulfuron PoE, while marginal benefit-cost ratio (MBCR) was highest with mesosulfuron + iodosulfuron (17.8) PoE followed by pinoxaden + metribuzin (50+150 g/ha) PoE. It was concluded that sequential application of PE followed by PoE herbicide with a rotational application of herbicides having different mode of action is suitable for management of herbicide-resistant P. minor in wheat.