Dichomitus

Dichomitus is a genus of bracket fungi (polypores) known for causing significant wood decay in forest ecosystems. The most notable species, Dichomitus squalens, acts as a primary pathogen that triggers white rot, systematically breaking down lignin and cellulose within the host's trunk.

The fungus is classified as a wood-decaying pathogen. It typically invades trees through physical injuries, broken branches, or logging damage. Once established, the mycelium spreads throughout the heartwood, weakening the structural integrity of the tree and predisposing it to failure.

Coniferous trees, particularly pines, are the primary hosts for this fungus. While it can attack seemingly healthy trees, it thrives most aggressively in stressed or aging stands where the natural defense mechanisms of the host are compromised, leading to substantial economic losses in timber production.

Symptoms of the disease are often progressive and include:

• Development of distinct annual or perennial fruiting bodies on the bark.
• Internal wood discoloration and degradation into a fibrous, white mass.
• Gradual crown thinning and yellowing of the needles.
• Increased risk of stem breakage and windthrow in infected areas.

The spread of the fungus is accelerated by high humidity and the availability of infection courts such as pruning wounds or frost cracks. Effective management strategies involve strict sanitation practices, such as removing infected trees, minimizing mechanical damage during harvest, and maintaining overall stand vigor through silvicultural thinning.