Phomopsis cane and leaf spot

Phomopsis viticola is a pathogenic fungus belonging to the kingdom Fungi, genus Phomopsis, and species Phomopsis viticola. It is the causal agent of Phomopsis cane and leaf spot, a significant disease affecting grapevines globally, particularly in regions with high humidity during the early growing season.

The disease primarily manifests on green shoots, leaves, and rachis of clusters. Early symptoms include small, dark spots or streaks, which often progress into necrotic lesions that can cause the affected tissue to crack and split. In severe cases, the infected shoots become brittle and may fail to mature properly, impacting the vine's structure.

The fungus overwinters as pycnidia in the bark of infected wood and in cane lesions. When temperatures rise above 8°C in the spring and moisture is present, the pycnidia release spores. Rain splashes and wind carry these spores to susceptible new shoots, where primary infections occur during the initial stages of vegetative growth.

Development and spread are favored by prolonged wet weather and moderate temperatures. Canopy density significantly influences the severity of the infection; vines with poor aeration are much more susceptible to the spread of Phomopsis viticola. The pathogen can colonize both current-year growth and older wood, leading to chronic infections if left unmanaged.

The economic impact of the disease involves reduced fruit yield, compromised vine health, and increased susceptibility to winter damage. Successful management requires a strategic approach:

• removing and burning infected wood during dormant pruning;
• implementing canopy management to improve airflow and reduce humidity;
• applying preventative fungicide sprays during the early bud break phase;
• ensuring proper sanitation within the vineyard to reduce spore inoculum;
• using certified disease-free propagation material.