Field studies were conducted from 1998 to 2000 in Beltsville, MD, to evaluate the effects of preemergence (PRE) applications of BAY FOE 5043 metribuzin, s-metolachlor, and diclofop on crop injury, yield, and control of diclofop-tolerant Italian ryegrass in winter wheat. No injury was observed in 1999. In 2000, minor stunting of wheat plants was observed where high rates of BAY FOE 5043 metribuzin and s-metolachlor were utilized. Wheat plants outgrew the stunting and grain yields were not affected. High rates of BAY FOE 5043 metribuzin and s-metolachlor provided equally effective Italian ryegrass control in 1999, averaging 85% or greater in June. In 2000, all rates of BAY FOE 5043 metribuzin provided 93% or greater Italian ryegrass control, whereas s-metolachlor at 0.43 kg/ha or greater provided 85% Italian ryegrass control or greater when evaluated in June. In 1999, wheat yields from plots treated with BAY FOE 5043 metribuzin, or s-metolachlor at 0.43, 0.56, or 0.84 kg/ha, were higher than from the nontreated control. In 2000, all wheat yields from plots treated with BAY FOE 5043 metribuzin and s-metolachlor were higher than from the nontreated control.
Nomenclature: BAY FOE 5043; diclofop; metribuzin; s-metolachlor; Italian ryegrass, Lolium multiflorum Lam. #3 LOLMU; wheat, Triticum aestivum L. ‘Jackson’.
Additional index words: Herbicide-resistant weeds.
Abbreviations: EP, early postemergence; POST, postemergence; PRE, preemergence.
