Blue cheese polypore

Blue cheese polypore (Latin: Postia caesia) is a wood-decay fungus belonging to the Fomitopsidaceae family. It is widely recognized in forestry as an agent of brown cubical rot. This fungus primarily acts as a saprotroph, decomposing dead wood, but under favorable conditions, it can also infect living trees that have been weakened by environmental stress or physical injuries.

The host range of Postia caesia is primarily focused on coniferous tree species, most notably spruce, fir, and pine. Occasionally, the fungus is found on broad-leaved species, such as birch or alder. It thrives in dense forests where moisture is consistently present, making it a significant factor in the natural decomposition cycle of forest ecosystems.

The symptoms of an infestation are marked by the appearance of small, fleshy, blue-grey or white caps on the surface of the wood. The internal tissues show clear signs of brown rot: the wood darkens, loses its structural strength, and fractures into distinct cubical shapes. As the decay progresses, the wood loses its economic value and becomes highly fragile.

The development of this pathogen is strictly tied to environmental conditions, particularly humidity and temperature. It prefers high-humidity environments where the wood moisture content is sufficient to support mycelial growth. Spore dispersal is facilitated by wind, allowing the fungus to settle on fresh bark cracks, wood wounds, or logging scars, eventually penetrating deeper into the stem tissues.

The economic impact of the fungus is significant, as it degrades the quality of timber and timber products. To prevent widespread infection, management strategies focus on sanitation. This includes the removal of infected trees, proper forest hygiene, and the protection of timber during storage to prevent the establishment of the mycelium.

• Remove infected logs and dead wood from forest stands.
• Ensure proper ventilation in storage areas for harvested timber.
• Minimize bark damage during timber harvesting operations.
• Apply fungicides or wood preservatives to protect exposed wood surfaces.