Control Methods for Herbicide Resistant Cheat and Italian Ryegrass in Winter Wheat.

There is an increasing interest in finding alternative options for controlling weeds in winter wheat. Metribuzin (applied in the form of Sencor®) has been successful in controlling problem weeds in small grains, but is not widely used because metribuzin is known to cause crop injury in winter wheat. One greenhouse study evaluated control of cheatgrass (Bromus secalinus) and Italian ryegrass (Lolium multiflorum) with metribuzin at 52.51, 105.05, 210.07, and 420.15 g AI/ha rates. Additionally, the sixteen most popular wheat varieties in the state of Oklahoma were evaluated in greenhouse and field trials for their response to metribuzin in order to develop recommended application rates for each variety. Metribuzin was applied at rates of 52.51, 105.05, 210.07, and 420.15 g AI/ha. Wheat was planted in the greenhouse into a Craig silt loam collected from a farmer's field in NE Oklahoma and into a Norge silt loam in the field trial located at the Oklahoma State Agronomy Farm. The wheat was harvested 14 d after planting. The results presented will show which rate is an acceptable rate both for the safety of the wheat crop and the control of the cheatgrass and Italian ryegrass.