Calosphaeria canker

Calosphaeria canker is a destructive fungal disease that affects the perennial wood of grapevines, caused primarily by the ascomycete fungus Calosphaeria pulchella. This pathogen is a significant contributor to the complex of trunk diseases that severely impact vineyards worldwide, leading to reduced productivity and premature decline of the plants.

The disease primarily targets grapevine cultivars, though it can colonize other woody hosts as well. By invading the vascular system through pruning wounds or environmental cracks in the bark, the fungus secretes enzymes that break down wood tissue, eventually leading to a blockage of water and nutrient transport throughout the vine's architecture.

Early symptoms are often subtle, but as the infection progresses, affected vines exhibit stunted growth, chlorosis of the foliage, and dieback of spurs or entire cordons. A characteristic diagnostic sign is the presence of brown to reddish-brown wood necrosis on cross-sections. Small, black, erumpent fruiting bodies of the fungus may appear on the bark surface near the infection sites.

Disease spread is highly dependent on humidity and the timing of vineyard activities. Spores are released during wet conditions and are disseminated by wind and splashing rain, landing on fresh pruning wounds, which serve as the primary entry points. The slow development of the disease makes it difficult to detect before significant internal damage has occurred.

Prevention and management strategies are crucial, as there is no curative treatment for infected wood. Recommended practices include:

• Strict sanitation and disinfection of pruning tools between vines.
• Application of protective wound sealants or biological control agents on major pruning cuts.
• Careful monitoring and removal of infected wood to reduce local inoculum pressure.
• Optimizing vineyard management to minimize vine stress and promote rapid healing of wounds.