Dialonectria sanguinea

Dialonectria sanguinea is an ascomycetous fungus responsible for causing bark necrosis and cankers on various woody plants. The pathogen is recognized by its distinct, blood-red or orange-red perithecia that develop on the surface of infected bark. As a necrotrophic parasite, it primarily targets the cortical tissues, eventually penetrating deeper into the sapwood.

This disease mainly affects broad-leaved trees, including species such as maples, lindens, and birches. It often acts as a secondary invader on trees already stressed by drought, poor soil conditions, frost cracks, or previous mechanical injuries, although it can occasionally infect seemingly healthy trees under favorable environmental conditions.

Symptoms of the infection typically include localized bark discoloration, followed by drying and fissuring. As the necrosis advances, the bark may sink or flake off. In the advanced stages, the fungus disrupts the transport of nutrients, leading to the wilting and eventual dieback of distal branches or, in severe cases, the entire tree trunk.

The development and spread of Dialonectria sanguinea are heavily dependent on humidity and moisture. Spores are disseminated via water splash, wind, or insect vectors, effectively landing on fresh wounds or bark crevices. The fungus overwinters within infected wood tissues, ensuring a persistent supply of inoculum throughout the growing season.

Integrated management strategies for controlling the disease include:

• Regular inspection and pruning of infected branches, ensuring cuts are made into healthy tissue.
• Sterilization of pruning tools to prevent the accidental transmission of spores.
• Application of protective wound dressings or copper-based fungicides on major cuts.
• Maintaining tree vigor through proper fertilization and watering to improve natural defenses.