Field studies were conducted to compare the effectiveness of PRE and POST applications of a prepackaged mixture of flufenacet plus metribuzin with that of diclofop for winter wheat tolerance and control of Italian ryegrass. Additional studies investigated the effectiveness of reduced rates of flufenacet plus metribuzin applied POST to Italian ryegrass when wheat was in the spike stage. All PRE and POST applications of flufenacet plus metribuzin produced similar or greater injury to wheat and more consistent control of Italian ryegrass than PRE or POST applications of diclofop. PRE applications of flufenacet plus metribuzin controlled Italian ryegrass 73 to 77%, whereas POST applications controlled Italian ryegrass 77 to 99%. PRE applications of diclofop controlled Italian ryegrass 57%; POST application controlled Italian ryegrass 78%. Wheat injury from flufenacet plus metribuzin applications varied with application rate, cultivar, and year of application.

Nomenclature: Diclofop; flufenacet; metribuzin; Italian ryegrass, Lolium perenne L. ssp. Multiflorum (Lam.) Husnot winter wheat, Triticum aestivum L.