Fomitiporia mediterranea

The fungus produces perennial, bracket-shaped, or resupinate fruit bodies on dead wood. These fruit bodies are typically brown, woody, and possess a porous hymenium on the underside.

Unlike many other decay fungi, Fomitiporia mediterranea is capable of both saprotrophic growth on woody debris and pathogenic behavior as a parasite within living tissues of woody plants.

The biology of this organism is characterized by a high tolerance for varying environmental conditions, allowing it to become a dominant species in Mediterranean climates and beyond.

Microscopic examination reveals the presence of hyphae with simple septa and an absence of clamp connections, which are definitive diagnostic characteristics used by plant pathologists to identify this species.

The primary host for this pathogen is the grapevine (Vitis vinifera), where it acts as a major agent in the complex disease syndrome known as esca or grapevine apoplexy.

Beyond vineyards, the fungus has a broad host range and can infect various deciduous trees and shrubs, including olive trees and ornamental woody plants found in agricultural landscapes.

The fungus invades the vascular tissues and the internal wood of the trunk and cordons, leading to severe disruption of water and nutrient transport systems throughout the plant.

It causes the degradation of lignin and cellulose, which weakens the physical structure of the plant's woody components, making them brittle and susceptible to environmental stress.

The economic impact is profound, resulting in decreased grape yields, the gradual decline of vine vigor, and the potential for sudden vine death, necessitating costly vineyard replanting.

Leaf symptoms typically appear in late summer as interveinal chlorotic areas that eventually develop into necrotic spots, creating a distinctive "tiger-stripe" pattern on the leaves.

Internally, the infected wood exhibits a white rot, characterized by a soft, spongy texture as the fungus breaks down the lignin structure within the xylem tissues.

The phenomenon known as "apoplectic strike" is a common symptom where the entire vine suddenly wilts and dies during hot, dry periods due to the failure of the compromised vascular system.

Cross-sections of affected trunks or cordons often reveal areas of dark, necrotic wood, frequently separated from healthy tissues by a dark margin indicating the plant's attempt to compartmentalize the infection.

In humid conditions, the characteristic fruit bodies of Fomitiporia mediterranea may emerge through cracks in the old bark of infected vines, releasing spores that can spread the disease.

Chemical control of this fungus is extremely challenging because the pathogen is situated deep within the wood, which is largely inaccessible to systemic and contact fungicides.

The most effective management strategy is rigorous sanitary pruning, which involves the complete removal of infected wood, followed by the disinfection of all cutting tools to prevent cross-contamination.

Applying protective wound sealants, including mastic or fungicidal pastes, to pruning wounds immediately after cutting is critical to prevent airborne spores from colonizing the exposed tissues.

It is recommended to avoid pruning during wet, rainy weather, as high humidity and moisture facilitate the dispersal and germination of fungal spores on vulnerable wound surfaces.

• Utilizing only certified disease-free propagation material.
• Removing and incinerating severely infected wood and stumps.
• Rejuvenating vines by training new cordons from the lower, healthy portions of the trunk.
• Maintaining optimal vineyard vigor through balanced fertilization and irrigation to improve plant resilience.