Graphostroma

Graphostroma is a genus of fungi including the species Graphostroma platani, which acts as a pathogen causing bark necrosis in trees. This fungal disease is categorized as a systemic necrotic infection that primarily targets the outer and inner bark tissues. By colonizing these tissues, the fungus disrupts nutrient transport and weakens the structural integrity of the affected plant species.

The primary host for this pathogen is the plane tree (Platanus genus). While the disease is predominantly found in managed landscapes and urban forests, it can also affect specimens in wild habitats. Trees subjected to environmental stressors, such as pollution, drought, or poor soil quality, are significantly more susceptible to successful colonization by the fungus.

The most recognizable symptoms of Graphostroma infection include the formation of irregular necrotic lesions on the bark. As the disease progresses, the pathogen develops stromata, which appear as black, crust-like structures breaking through the bark surface. Eventually, these lesions cause the death of distal branches and, in severe cases, the entire tree can succumb to vascular failure.

The development and spread of this disease are heavily influenced by environmental conditions, particularly high humidity and moderate temperatures that favor spore germination. Transmission occurs primarily through wind dispersal of spores or by water splashes during rain events. Furthermore, pruning tools that are not sterilized can easily transfer the fungus between infected and healthy trees.

Mitigating the impact of Graphostroma requires a comprehensive management approach focused on prevention and sanitation. Key protective measures include:

• Regular inspection of trees to detect early signs of bark lesions.
• Prompt removal and safe disposal of infected limbs to reduce inoculum pressure.
• Strict sanitation protocols for all pruning equipment using appropriate disinfectants.
• Promoting tree vigor through balanced fertilization and proper irrigation during dry spells.