Differential Tolerance of Winter Wheats to, and the Efficacy of Bromus Control Herbicides

Field experiments were conducted to evaluate the tolerance of 86 winter wheat (Triticum aestivum) cultivars to cyanazine, ethiozin, and metribuzin. Among the more cyanazine and ethiozin tolerant hard red winter wheats with known pedigrees, their pedigrees included 'Hope' and/or 'Cheyenne' parentage. However, the cultivars more sensitive to ethiozin, notably those with 'Vona' parentage, were not consistently sensitive to cyanazine. Among the white wheats, based on yield data, 'Hill 81' and 'Lewjain' were distinctly more sensitive to metribuzin and ethiozin than four other cultivars. As with the above classes of wheat, visual injury on the soft red wheats did not consistently correlate with yield reductions. In contrast to the hard red wheats, as a class the soft red wheats were generally more sensitive to cyanazine than ethiozin. Nomenclature: Cyanazine, 2-[[4-chloro-6-(ethylamino)-1,3,5- triazin-2-yllaminol-2-methylpropanenitrile; ethiozin3 , 4-amino-6-(1,1- dimethylethyl)-3-(ethylthio)-1,2,4-triazin-5(4H)-one; metribuzin, 4- amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one; cheat, Bromus secalinus L. #4 BROSE; winter wheat, Triticum aestivum L. Additional lndex words: BAY SMY 1500, cheat, hard red winter wheat, soft red winter wheat, white winter wheat.Agronom