Cleanly cut wounds on the surface of green apricot fruit are susceptible to infection with Monilinia fructicola when freshly made, but rapidly become resistant over 6 h. This was shown to be strongly correlated with the concentration of free nutrients, particularly sugars, which remain on the surface of the wound. Nutrients were rapidly removed by diffusion and absorption by underlying living cells. This is proposed as the basis of resistance which develops rapidly as the wounds age. Structural and chemical barriers to infection, such as periderm, suberin and phenolic compounds, developed long after the wounds had become resistant.