Field research was conducted in 1983 and 1984 at Scottsbluff, NE, to determine the effect of cyanazine {2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methyl-propanenitrile} applied in corn (Zea mays L. ‘Pioneer 3732’) on fieldbeans (Phaseolus vulgaris L. ‘Valley’) planted 30 days later to replace corn. Cyanazine preplant incorporated at 1.1 kg ai/ha or higher reduced the vigor, stand, and yield of fieldbeans as a replant crop.