Phaeoacremonium amygdalinum

Symptoms often manifest as stunted growth of shoots and leaves, which may appear smaller than normal and show signs of chlorosis or necrosis.

A hallmark of this disease is the development of dark internal streaking or brown spots visible upon cross-sectioning the trunk or cordons.

Leaves on infected vines may exhibit interveinal yellowing or browning, eventually drying out during the peak of the growing season.

In advanced stages, the infected vine may show a sudden collapse, known as apoplexy, where entire sections die off due to complete vascular failure.

• Stunted vegetative growth.
• Chlorotic and necrotic leaf spots.
• Internal wood discoloration.
• Vascular system dysfunction.
• Progressive branch dieback.

Phaeoacremonium amygdalinum is a fungal pathogen belonging to the Togniniaceae family, recognized as a significant agent in wood disease complexes.

This pathogen primarily colonizes the xylem tissue of woody perennials, specifically affecting grapevines and other susceptible agricultural crops.

The fungus operates by growing within the vascular system, gradually inhibiting the conduction of water and essential nutrients throughout the plant.

It remains dormant in infected wood for extended periods, making early detection extremely difficult for farmers and agronomists.

Infection typically occurs through pruning wounds, where spores land on fresh cuts and begin their slow colonization of the host's woody structure.

The development of the fungus is highly dependent on humidity levels, particularly during the pruning season when fresh wounds are exposed.

Temperatures ranging from warm to moderate promote the mycelial growth and spore production of the pathogen within the host tissue.

Human-mediated transmission is a primary concern, as pruning shears carry the spores between healthy and infected plants if not properly sterilized.

Environmental stress factors, including drought or imbalanced irrigation, predispose the plant to colonization by lowering its natural defense mechanisms.

The presence of exposed, untreated pruning wounds acts as an entry point for fungal spores dispersed by wind or splashing rain.

The primary damage caused by this pathogen is the irreversible destruction of the plant's structural and vascular integrity over several years.

Infected plantations suffer from significant yield losses and reduced fruit quality, as the vines cannot support proper ripening processes.

The disease reduces the longevity of vineyards, forcing growers to invest in expensive replanting and removal of diseased woody material.

Once established in the trunk, the fungus acts as a persistent reservoir of inoculum, threatening surrounding healthy plants in the vineyard.

The cumulative financial impact includes lower productivity, increased management costs, and the need for frequent monitoring of plant health.

Effective control depends heavily on preventative measures because curative treatments for wood infections are largely ineffective once the fungus is deep inside.

Strict hygiene protocols must be followed, including the systematic disinfection of all pruning tools using alcohol or chlorine-based solutions.

All pruning wounds, especially large ones, should be protected immediately after cutting with fungicidal pastes to prevent spore entry.

Regular monitoring and surgical removal of infected plant parts are necessary to reduce the overall inoculum pressure within the field.

Maintaining optimal vine vigor through balanced fertilization and appropriate irrigation helps improve the plant's resilience against such fungal infections.