Preventing Stain in Pine Logs by "Sour Felling" and Biological Protection of Sawlogs Against Bluestain
Sundance Forest Industries Ltd.
Lead Researcher: 
Tony Bryne, Dave Minchin and Adnan Uzunovic, Forintek Canada Corp., Vancouver, British Columbia
It is estimated that bluestain fungi cost the Alberta forest industry at least $30 million in 1998. This study explores the potential for reducing bluestain through the use sour-felling techniques (the delayed delimbing of felled trees) and biocontrol agents.

Three sour-felling trials were conducted in 1999, 2000, and 2001. The trials measured the amount of blue-stain in both sour-felled and delimbed trees following 6-7 and 12-13 weeks of summer storage. It was found that during summers where bluestain developed, there was significantly less stain in sour-felled trees. In addition, logs that had been sour-felled tended to develop much less surface mould growth than the logs that had been delimbed at the time of harvest. The finding is most likely attributed to the reduction in bark damage, moisture or nutrients in the sour-felled trees.

The biocontrol portion of the study was completed in summer 2000. The trial tested the feasibility of using biocontrol agents Cartapip and Gliocladium roseum to protect logs from bluestain fungi. Both Cartapip and Gliocladium roseum showed promise in preventing stain from developing during the critical first 12 weeks of storage in freshly felled logs. However, further trials are required to ensure consistent results prior to use of the biocontrol agent industrially.

Bluestain appears to be more prevalent in logs with larger butt diameters. However, it is undetermined as to the specific summer conditions that cause logs to have a higher susceptibility bluestain fungi, and therefore when sour-felling and biocontrol agents could be appropriately employed.