During 1998-1999, a study was initiated to investigate the influence of seasons, log types, and storage time on the sapstain development of jack pine logs at three sites in Eastern Canada. Jack pine trees (Pinus banksiana) were harvested into full-length and cut-to-length logs in spring and in autumn. Sapstain development was examined in these logs at intervals of 2 to 4 weeks after felling. The mean stain coverage and mean maximal radial penetration of stain in wood were measured from the discs of the sampled logs. The spring trial showed that sapstain did not develop significantly on jack pine logs within 4 weeks after trees were felled; however, the severity of stain increased proportionally with storage time. The full-length logs were more stained than the cut-to-length logs in the spring felling. All logs were seriously stained after the 3 months of summer storage. The autumn trial showed that logs felled after September were stored in the sawmills over winter without significant stain, but stain development was rapid after April of the following year. Debarking logs did not reduce stain development on wood. In fact, the growth of stain was more rapid on debarked logs than on logs with the bark. The main fungus isolated from stained wood was Ceratocystis coerulescens. Bark beetle attack was found in logs within 4 weeks of the spring harvest. The species of bark beetle was Ips pint. After 3 months of summer storage, decay started to develop in these logs. The main causal species was Schizophyllum commune
