Eleven field experiments were conducted to evaluate atrazine for selective cheat control in hard red winter wheat. Cheat control with atrazine at 140 glha applied PRE varied from 5 to 83% but was similar to cheat control with the standard treatment, triasulfuron at 29 glha. Control with atrazine at 280, 560, and 840 glha applied early POST exceeded control with the standard treatment, triasulfuron plus metribuzin at 29 plus 157 glha, in one, three, and five experiments, respectively. Metribuzin at 420 glha was the standard treatment for cheat control in tillered wheat and controlled cheat 28 to 96%. Cheat control with atrazine at 560 and 840 glha applied to tillered wheat was comparable to or exceeded the standard. Of the early POST treatments the standard increased yield in three of five experiments. Triasulfuron plus atrazine applied POST at 29 plus 280 glha also increased wheat yield in three offive experiments and yields did not differ from the standard treatment at the other two experiments. In on-farm experiments, cheat control with atrazine at 560 glha was similar to control with metribuzin at 420 glha in two of three experiments. In these experiments five of six treatments of metribuzin at 420 glha increased yield and four of six treatments of atrazine at 560 glha increased yield. In cultivar tolerance experiments the metribuzin tolerant cultivars 'TAM W -101' and '2180' were much more severely injured by atrazine applied POST at 840 glha than 'Karl 92', a cultivar considered less tolerant to metribuzin. Nomenclature: Atrazine,6-chloroN- ethyl-N' -(l-methylethyl)-l, 3, 5, -triazine-2, 4-diamine~ metribuzin, 4-amino-6-( 1, 1- dimethylethy)-3-(methylthio )-1, 2, 4-triazin-5( 4H)-one; triasulfuron, 2-(2-chloroethoxy)N-[[ (4-methoxy-6-methyl-1, 3, 5-triazin-2-yl)amino ]carbonyl]-benzenesulfonamide; cheat, Bromus secalinus L. #3, BROSE; wheat, Triticum aestivum L. Additional index words: Metribuzin, triasulfuron, BROSE,
