Fomitiporia mediterranea

Fomitiporia mediterranea is a destructive wood-decaying fungus that acts as a primary pathogen involved in the complex disease known as grapevine esca. This basidiomycete fungus targets the vascular system of the vine, causing progressive internal rot that eventually leads to the death of the woody parts of the plant.

While the grapevine is the most economically significant host for this pathogen, it has a broad host range, infecting various deciduous trees and fruit crops. Its ability to persist as a saprophyte in dead or dying wood allows the pathogen to remain present in vineyard environments for many years, acting as a constant source of inoculum.

Clinical signs of infection include the well-known "tiger stripe" symptoms on leaves, where interveinal chlorosis is followed by necrosis. Internally, the trunk exhibits significant white rot, transforming the hard wood into a brittle, spongy mass. In advanced stages, the infected vine may show a sudden collapse, often referred to as "apoplexy" during hot, dry summer periods.

The fungus primarily spreads through airborne spores that germinate on pruning wounds. Factors such as the age of the vineyard, the size of pruning cuts, and environmental conditions (specifically high humidity during the pruning season) heavily influence the rate of disease development across a plantation.

Management of this disease is highly challenging due to the internal nature of the infection, which makes chemical control ineffective once the fungus is established. Therefore, integrated pest management strategies must focus on strict prophylactic measures to protect the vines:

• Performing pruning operations during dry weather to minimize spore germination risks.
• Disinfecting all pruning tools between vines using appropriate sanitizing solutions.
• Applying wound sealants or protective paints to all pruning cuts larger than 2 centimeters in diameter.
• Removing and destroying heavily symptomatic plants to reduce the overall fungal pressure.
• Prioritizing sanitary practices in nurseries to ensure the propagation of pathogen-free rootstock.