Red fire disease of grapevine

Red fire disease, caused by the fungus Pseudopeziza tracheiphila, is a significant fungal infection affecting grapevine foliage. The pathogen attacks the vascular tissue of the leaves, resulting in the necrosis of the tissue and severe interference with the plant's physiological functions.

The disease primarily impacts Vitis vinifera varieties. It is prevalent in regions with high humidity and temperate springs. Unlike some other fungal diseases, this pathogen specifically targets the conductive elements of the leaf, leading to characteristic symptoms that distinguish it from mildews.

Symptoms initially appear in late spring as angular spots between the veins. On white grape varieties, these spots turn yellowish-brown, while on red varieties, they exhibit a distinct red or mahogany coloration. As the infection progresses, these lesions enlarge, causing the leaves to wither and drop prematurely.

The fungus overwinters on fallen leaves in the vineyard litter. During damp spring weather, the spores are released and carried by wind or splashing rain to the healthy foliage. High humidity and cool-to-moderate temperatures are essential for the primary infection and subsequent spread of the disease within the vineyard canopy.

Control strategies are essential to maintain vine health and yield quality:

• Sanitation practices, including the removal and destruction of fallen leaves, which serve as the primary inoculum source.
• Improving airflow within the vineyard through proper pruning, canopy management, and trellising.
• Applying preventative copper-based fungicides or other authorized chemical treatments during the early leaf development stages.
• Monitoring the vineyard consistently during wet spring weather to apply protective measures before symptoms become widespread.