Cauliflower fungus

Cauliflower fungus (lat. Sparassis crispa) is a parasitic fungus recognized as a significant cause of brown cubical rot in the root systems and the lower stems of coniferous trees. Although often noted for its culinary use, from a forestry perspective, it is a destructive pathogen that compromises the structural integrity of forest ecosystems.

This fungus primarily affects conifer species, with Scots pine being the most susceptible host. It typically infects trees through wounds on the roots or lower trunk or via root grafting between adjacent trees in a forest stand, slowly spreading through the soil from infected to healthy root systems.

The most distinctive symptom is the emergence of large, yellowish, cauliflower-like fruiting bodies at the base of the infected tree. Internally, the fungus decomposes the wood by attacking cellulose and lignin, causing the wood to become brittle, brown in color, and eventually fracture, which makes the tree highly susceptible to windthrow.

Development of the disease is favored by high soil moisture levels and stable temperature conditions. The mycelium penetrates deeply into the heartwood of the roots and the base of the stem, continuing to decay the wood even after the tree has lost much of its ability to transport nutrients and water from the soil.

The severity of this disease lies in the reduction of stand quality and the increased risk of tree mortality. Management strategies focus on sanitation logging to remove infected trees, stump removal, and minimizing site disturbances that can lead to root wounds. Maintaining forest diversity and vigor is essential to limit the spread of the pathogen.

• Sanitary removal of infected host trees.
• Root-stump extraction to eliminate inoculum.
• Protection of trees from mechanical damage.
• Regular forest health surveys and monitoring.