Fungal infection of logs and lumber can occur in standing trees, and during harvesting, transport and storage. Such infections often appear as a visible discoloration of wood termed sapstain. This occurs predominantly on sapwood and is caused by a mix of bluestain fungi, moulds and/or decay fungi. Control of sapstain fungi can be achieved by rapid processing and kiln drying, or by using sapstain control products (antisapstain treatments). Sapstain control products are primarily intended to prevent new infections on green wood, and have limited capacity to arrest existing infections. The effect of pre-infection of logs or lumber on sapstain control product efficacy is poorly understood, and has been rarely investigated. Clear guidelines are needed on acceptable delay periods for log storage, or before sapstain control products are applied on lumber. Sawmill operators need to know the impacts of handling and storage practices to sapstain control product efficacy. The present work reviews the literature addressing pre-infection. In addition we compared the performance of fresh and pre-infected lumber in an antisapstain field test. In our experiment the sapstain control product at the highest (2 times recommended) concentration was generally able to control sapstain in freshly cut material. Incubation of pre-infected lumber for three days prior to the treatment was not associated with higher ratings (increase in visible fungal growth) in most samples. However, incubation of pre-infected lumber for seven days prior to the treatment was associated with increased surface growth by bluestain fungi. Under the conditions of this experiment a delay of one to three days before treatment application to lumber could be tolerated. However, there are numerous factors (e.g. local climate, degree of pre-infection, wood species, nature of chemicals applied) that may play a role in product efficacy, and it is not easy to pin-point an acceptable period between harvest and sapstain control product application. It is thus safest to apply sapstain control products with minimal delay.