White stringy rot

White stringy rot, caused by the basidiomycete fungus Resinicium bicolor, is a significant wood-decay disease primarily affecting coniferous species. The fungus is known for its ability to aggressively break down wood structure by degrading both cellulose and lignin, leading to rapid decay.

The disease frequently targets Douglas Fir trees, causing substantial economic losses in forest management. Infection typically begins through root contact with infested organic matter in the soil or through entry wounds on the trunk caused by environmental stress or mechanical logging injuries.

The primary symptom is the transformation of wood into a soft, fibrous, and stringy mass. This decay compromises the structural integrity of the tree, often resulting in windthrow or stem breakage, especially during severe weather conditions. Internally, infected areas often display a characteristic bleached, pale appearance.

Development and spread of the pathogen are accelerated by warm and moist conditions, which are ideal for fungal growth. The fungus persists in the soil and on old tree stumps, allowing it to bridge the gap between infected and healthy trees through root grafting or close proximity, slowly expanding the disease centers in a stand.

Effective management and prevention focus on limiting the opportunities for the fungus to establish itself. These strategies include maintaining forest hygiene, minimizing logging damage, and ensuring proper site preparation before replanting. Regular monitoring of Douglas Fir plantations is crucial to identify and isolate infected pockets before the rot causes widespread timber loss.