Perenniporia subacida

Perenniporia subacida is a wood-decay basidiomycete fungus belonging to the Polyporaceae family. It is a well-known plant pathogen classified as a saprotroph and a facultative parasite. The fungus is responsible for causing white stringy or white corrosion rot in the heartwood and sapwood of various coniferous and deciduous tree species.

The disease primarily manifests as root rot and butt rot. It affects trees by colonizing the root system and spreading upwards into the lower trunk. Common hosts include spruce, fir, and pine. The decayed wood often exhibits a distinct acidic smell, which is a key characteristic used for field identification of the pathogen's presence in forest stands.

The life cycle begins with the production of perennial basidiocarps, which release spores that disperse through wind. Infection occurs primarily through wounds, frost cracks, or exposed roots. Once established, the mycelium secretes enzymes that degrade lignin and cellulose, leading to the structural weakening of the host tree. Development is favored by cool, moist conditions often found in boreal and temperate forests.

The pathogenicity of Perenniporia subacida is significant due to its impact on tree stability and tree mortality. By destroying the root architecture, the fungus increases the susceptibility of trees to windthrow. Furthermore, the economic loss is substantial as the wood loses its commercial value due to the advanced state of decomposition caused by the fungus.

Control measures and management strategies focus on preventing the spread of the fungus within the forest environment:

• Implementing strict sanitary logging practices to remove infected material;
• Minimizing physical damage to healthy trees during thinning operations;
• Treating freshly cut stumps with biological control agents or fungicides;
• Maintaining forest site diversity to reduce the rate of fungal transmission between root systems.