Eutypa dieback

Eutypa dieback, caused by the ascomycete fungus Eutypa lata (kingdom Fungi, genus Eutypa, species Eutypa lata), is one of the most destructive diseases affecting the perennial wood of grapevines. This pathogen causes systemic vascular infection, leading to a slow decline of the vine, reduced productivity, and eventually the death of the entire plant.

Symptoms of Eutypa dieback are most visible during the spring, characterized by stunted shoots with short internodes and small, chlorotic, cupped leaves. A hallmark of the infection is the presence of wedge-shaped necrotic zones inside the trunk or cordons, which can be seen upon cross-sectioning. These lesions represent areas of wood destroyed by the fungal toxins secreted during its slow colonization of the vascular system.

The disease cycle begins with the formation of perithecia on dead or dying wood. During rainfall events, ascospores are released into the air and travel over long distances via wind. The infection typically initiates through pruning wounds or other mechanical injuries. Once the spores germinate, the fungus colonizes the wood tissue, and the infection progresses internally, often remaining latent for several years before outward symptoms appear.

The development of Eutypa lata is strongly favored by periods of high humidity and rainfall, which facilitate spore release and germination. The economic impact is severe, as the infection renders affected cordons unproductive, significantly reducing the lifespan and yield of the vineyard. Because the disease is chronic, it necessitates long-term management strategies to prevent widespread colonization of the vineyard.

Effective control of Eutypa dieback relies on rigorous sanitary and cultural practices:

• Performing pruning during dry conditions to minimize the risk of spore infection.
• Applying protective wound dressings or fungicides to all large pruning cuts immediately after cutting.
• Sanitizing tools regularly and removing all infected wood from the vineyard to reduce the local inoculum.
• Rogueing and destroying heavily infected vines to protect the remaining healthy plants.