Influence of Paddy Residue Management Techniques on the Bioefficacy of Herbicides for Control of Phalaris minor in Rice-Wheat System

Field experiments were conducted during 1998–99 and 1999–2000 on sandy loam soils to study the bioefficacy of isoproturon, tralkoxydim, clodinafop, fenoxaprop-p-ethyl and sulfosulfuron for the control of Phalaris minor in wheat with respect to different paddy residue management techniques (straw removal, complete burning, partial burning and incorporation). The differences in wheat grain yield were non-significant with different paddy residue management systems during 1998–99, however, during 1999–2000, significantly highest grain yield was recorded with full rice straw incorporation 8.0 t ha⁻¹) than partial burning and rest incorporation of the straw. On an average of two years, whole incorporation of rice straw increased grain yield by 2.3% over straw removal treatment. Application of isoproturon even at double the recommended dose did not control P. minor effectively and gave significantly lower grain yield as compared to tralkoxydim (0.35 kg ha_-1), clodinafop (0.06 kg ha⁻¹), fenoxaprop-p-ethyl (0.10 kg ha⁻¹) and sulfosulfuron (0.025 kg ha⁻¹) under all the residue management systems. Poor control of P. minor with isoproturon even at double the recommended rate may be due to the development of resistance in P. minor to this herbicide.