Pseudopezicula tracheiphila

Systematic position and pathogen type: Pseudopezicula tracheiphila is an ascomycete fungus classified within the order Helotiales. It is a highly specialized plant pathogen responsible for causing a specific vascular disease in grapevines, commonly referred to as "Rotbrenner" or grapevine red burn.

Diseases and hosts: The pathogen primarily affects the common grapevine (Vitis vinifera). The infection manifests as distinctive necrotic lesions on leaves. In red-fruited cultivars, these spots appear reddish-brown, while in white-fruited varieties, they are yellow-brown, typically clearly delineated by the leaf veins.

Biology and life cycle: The fungus overwinters as mycelium within fallen, infected leaves on the vineyard floor. During wet spring conditions, the fungus produces apothecia that release ascospores. These spores are dispersed by rain splash onto young leaves, where they infect the plant through the stomata, eventually colonizing the vascular tissues and obstructing nutrient flow.

Developmental conditions and impact: Disease outbreaks are strongly associated with cool, rainy spring weather. High humidity is a critical factor for spore germination and infection establishment. The economic impact is significant: premature leaf drop weakens the vine, leads to lower sugar accumulation in berries, poor wood maturation, and increased susceptibility to winter damage.

Management and control measures: Controlling Pseudopezicula tracheiphila requires a combination of sanitation and chemical strategies:

• Rigorous removal and destruction of fallen leaves to eliminate the primary inoculum source.
• Improving vineyard canopy management to enhance airflow and leaf drying speed.
• Timely application of authorized fungicides, particularly during early growth stages.
• Monitoring the vineyard for early symptoms to implement targeted spray programs before the disease spreads.