The effect of a turbulent flow on the rate of reconnection of magnetic field lines by a tearing instability is calculated numerically. The reconnection rate is shown to be reduced by the turbulent flow. The turbulent flow transfers energy from the growing tearing instability into shorter wavelength electromagnetic modes that are stable, thereby reducing the rate of reconnection of magnetic field lines by the longer wavelength tearing instability. The numerical results presented contradict the prediction of a turbulence theory of Diamondetal. [Phys. Fluids27, 1449 (1984)] that a turbulent flow causes an anomalous diffusivity (resistivity) which increases the growth rate of tearing modes.