Rosellinia mammiformis

Rosellinia mammiformis is a fungal pathogen belonging to the Roselliniaceae family, known for causing wood decay and root rot in various deciduous tree species. As an ascomycete fungus, it primarily acts as a saprophyte on dead organic matter but can become an opportunistic parasite when trees are stressed or wounded.

This fungus typically affects broad-leaved trees and shrubs, including oak, beech, elm, and maple. It enters the host through wounds, frost cracks, or mechanical damage on the trunk and roots. Once established, it gradually colonizes the cambium and inner bark, disrupting the nutrient and water transport system of the plant.

The most distinctive symptom of an infection is the formation of small, black, wart-like or nipple-shaped fruiting bodies known as perithecia on the surface of the bark. Upon peeling away the bark, a dense white to cream-colored mycelial mat is often visible, which actively degrades the underlying wood, leading to localized necrosis and eventual branch dieback.

Environmental conditions play a critical role in the development and spread of Rosellinia mammiformis. It thrives in high-humidity environments, poorly drained soils, and shaded areas with poor air circulation. Spores are primarily dispersed by wind and rain splash, while mycelial spread can occur through root contact in infested soil environments.

Management strategies focus on maintaining tree vigor and minimizing wounding. Recommendations include:

• Removing and destroying infected wood and root remnants.
• Ensuring proper soil drainage to prevent excessive moisture.
• Sanitizing pruning tools to prevent disease transmission.
• Applying protective wound dressings to large cuts or damage.
• Monitoring vulnerable or stressed trees for early signs of bark discoloration.