N-[Heterocyclicaminocarbonyl]-8-quinolinesulfonamides such as N-[(4,6-dimethoxy-1,3,5-triazin-2-yl)aminocarbonyl]-8-quinolinesulfonamide or N-[(4,6-dimethoxypyrimidin-2-yl)aminocarbonyl]-8-quinolinesulfonamide are useful for plant growth retardation, brush control and weed control in crops.