Interference of Powell amaranth (Amaranthus powellii S. Wats. ♯ AMAPO) in sugarbeet (Beta vulgaris L. ‘Mono Hy A4’) was determined in field experiments. Yield of sugarbeet roots and recoverable sucrose/ha decreased as the density of Powell amaranth increased. At densities of 6, 12, 18, and 24 Powell amaranth plants/30 m of row, root yields were reduced 8, 14, 24, and 25%, respectively, and recoverable sucrose yields were reduced 7, 13, 23, and 24%, respectively. The minimum number of Powell amaranth plants required per 30 m of row to reduce sugarbeet root yields was estimated to be nine in 1982 and 11 in 1983.