Phomopsis of grapevine

Diaporthe tanakae is a pathogenic fungus known as the causative agent of phomopsis, often referred to as cane blight or dead arm disease in viticulture. This pathogen specifically targets grapevine tissues, affecting both the vegetative growth and the structural integrity of the vines over time.

The disease primarily attacks young shoots, leaves, and rachises of the clusters. As the infection progresses, it disrupts the vascular system of the plant, potentially leading to the death of individual shoots and significantly reducing the overall yield potential of the vineyard.

Key symptoms include the development of small black spots or lesions on the internodes of young shoots, which later evolve into elongated, necrotic cracks. When the disease affects the leaves, it creates small brown spots with chlorotic halos, causing the leaf tissue to deform and eventually shed prematurely.

The proliferation of Diaporthe tanakae is heavily dependent on environmental conditions, particularly high humidity and rainfall during the early spring growing season. Rain splashes facilitate the dispersal of fungal spores from overwintered infected wood to healthy green tissues, allowing the disease to spread rapidly through the vineyard.

Effective control measures focus on preventive strategies, such as the meticulous removal and destruction of infected canes during winter pruning. Integrated pest management, including the application of fungicides starting from the bud-break stage and ensuring proper vineyard ventilation, is essential to minimize the economic impact of the disease.

• Removal of infected plant debris
• Application of protective fungicides
• Improving canopy aeration and sunlight exposure
• Monitoring early season rainfall