Togninia

Visible symptoms often include foliar chlorosis and necrosis, frequently characterized by a tiger-stripe pattern on the leaves.

Cross-sections of the trunk or cordons reveal dark, woody discolorations or necrosis, indicating damaged vascular pathways.

Sudden vine collapse, often called apoplexy, may occur during hot summer days as the compromised root system fails to supply water.

Infected vines typically show stunted growth, reduced internode length, and overall lack of vigor compared to healthy counterparts.

Clusters on affected vines may fail to ripen properly, showing uneven berry size and necrotic spots that diminish overall yield quality.

The disease is caused by fungi of the genus Togninia, most notably Togninia minima, which is the teleomorph of Phaeomoniella chlamydospora.

These pathogens are classified as grapevine trunk diseases (GTDs), which specifically target the vascular system of the wood.

The fungus is systemic, meaning it colonizes the xylem vessels, blocking the upward movement of water and nutrients throughout the vine.

It survives in the woody tissue of infected vines and can persist in pruning debris for several years under favorable conditions.

Spore dispersal occurs primarily through rain splashes and wind, making the disease highly transmissible during wet weather conditions.

Warm and humid environments promote the maturation and release of fungal spores, increasing the risk of new infections during the season.

Pruning wounds serve as the primary entry points; pruning during rainfall significantly increases the likelihood of fungal colonization.

Mechanical damage to the vines, such as those caused by cultivation equipment or heavy storms, creates susceptible entry sites.

Vineyards that are under nutritional stress or have poor drainage systems are more prone to severe outbreaks of the disease.

Lack of tool sanitation during pruning operations is a major factor in the rapid spread of the pathogen across healthy blocks.

Togninia leads to a chronic decline of the grapevine, eventually resulting in the complete death of the vine structure.

The economic impact is substantial due to the cumulative loss of productive vines and the high cost of vineyard renewal.

Yield loss is significant, as the reduction in water and nutrient flow directly affects cluster development and berry maturation.

Because the disease is deep-seated in the wood, infected plants cannot be cured using conventional spray-based control methods.

The disease acts as a long-term threat to the longevity and profitability of vineyards, often requiring massive replanting efforts.

Strict sanitation protocols during pruning are essential; tools must be disinfected after every single vine to prevent cross-contamination.

Pruning should be scheduled during dry weather to allow natural wound sealing and minimize exposure to airborne spores.

Applying protective wound sealants immediately after cuts effectively blocks the pathogen from colonizing the exposed woody tissue.

Infected wood should be removed from the vineyard and burned or disposed of promptly to reduce the overall inoculum pressure.

Sourcing high-quality, certified nursery stock ensures that the pathogen is not introduced into the vineyard from the very beginning.