Phomopsis cane blight

The causative agent of this disease is the fungus Phomopsis viterbensis, which primarily affects grapevines. This pathogen is known for its ability to damage both green tissues and woody parts of the vine, posing a significant threat to vineyard longevity and fruit quality.

The infection targets various parts of the vine, including young shoots, leaves, petioles, rachises, and berries. It is particularly dangerous because it can colonize the internal tissues of the vine, leading to structural damage and systemic weakening of the plant structure over several growing seasons.

Symptoms appear early in the spring as small black spots or streaks on the basal nodes of shoots. As these shoots elongate, the bark may split, creating characteristic lesions. Leaf symptoms often manifest as dark, necrotic spots surrounded by a yellow halo, which can cause foliage to become brittle and eventually drop off prematurely.

The disease thrives under conditions of high humidity and cool to moderate temperatures. Rain splashes are the primary mechanism for dispersing fungal spores throughout the canopy. The pathogen overwinters within the infected canes and trunks, making it highly persistent if strict sanitation practices are not followed.

Effective management requires a multi-pronged approach:

• Rigorous pruning of infected wood during dormancy.
• Removal and destruction of prunings to reduce inoculum pressure.
• Application of protective fungicides during the bud break stage.
• Continued monitoring and systemic treatment during the rapid growth phase.

Strategic fungicide use, particularly during the critical early spring period, is essential for minimizing crop losses. Integrated pest management (IPM) practices, including canopy management to improve airflow and reduce moisture, play a crucial role in preventing outbreaks of Phomopsis blight in commercial vineyards.