Flufenacet controls multiple herbicide resistant Phalaris minor Retz. in wheat.

Phalaris minor Retz. is the major grass weed of wheat, which has developed resistance to multiple herbicides working through three modes of action. The identification of suitable herbicides with different modes of action will assist in the control of this weed in resistance affected areas. Keeping this in view, the efficacy of flufenacet, an oxyacetanilide herbicide, was investigated in 2013 and 2014 at Ludhiana, India. Three doses of flufenacet (200, 250 and 300 g ha⁻¹) were tested at three application timings on Zadoks wheat stages (Z00, Z13 and Z21) and compared with clodinafop application and weedy check for the control of resistant P. minor biotype. Flufenacet 250 and 300 g ha⁻¹, applied at Z00 and Z13 wheat stages, had more than 85% mortality and more than 90% growth reduction of P. minor compared to the unsprayed check (76–109 plants m⁻²; 60–69 g m⁻²) at 45 days after sowing in both years, whereas clodinafop just provided 26–37% reduction in density and 39–40% reduction in biomass of this weed. Flufenacet 250 g ha⁻¹ at Z00 and Z13 produced better wheat grain yield (4.2–4.5 t ha⁻¹) in both years, while weed competition in the unsprayed check reduced wheat grain yield by 54–67% (1.75–1.97 t ha^-1). This study suggests that flufenacet could be used to control multiple herbicide resistant P. minor in northern Indian wheat production systems. • Flufenacet 250 – 300 g ha⁻¹ applied at Z00 and Z13, provided >85% mortality and >90% growth reduction of P. minor. • Clodinafop @ 60 g ha⁻¹ provided only 26–37% reduction in density and 39–40% reduction in biomass of P. minor. • Flufenacet efficacy was higher in 2014 over 2013, owing to higher rainfall events in second year. • Flufenacet 250 g ha⁻¹ applied at Z00 and Z13 produced better wheat grain yield (4.2–4.5 t ha⁻¹) in both years. • Flufenacet provided better control of resistant P. minor population as compared to clodinafop. [ABSTRACT FROM AUTHOR]