Corky bark disease

Corky bark disease is a serious viral affliction that belongs to the rugose wood complex affecting grapevines. The primary causal agent is the Grapevine virus B (GVB), which is a member of the Vitivirus genus. As a systemic pathogen, it colonizes the vascular tissues of the plant, significantly hindering the movement of nutrients and water.

This virus specifically targets cultivated grapes (Vitis vinifera). The primary method of transmission is the use of infected propagation material, such as cuttings or rootstocks. Additionally, the disease can be spread in nurseries and vineyards by insect vectors, primarily mealybugs (e.g., Planococcus ficus), which acquire the virus while feeding on infected vines and transmit it to healthy ones.

The characteristic symptoms typically appear on the canes. As the season progresses, the bark on one-year-old shoots becomes thickened, corky, and cracked, giving it a rough appearance. Growth is stunted, internodes are often shortened, and the shoots may show distinct bending or twisting patterns. Foliage may exhibit premature yellowing or reddening, indicating that the plant's physiological processes are failing.

The economic impact of Corky bark is significant. Infected vines show a steady decline in vigor and structural integrity, leading to a drastic reduction in fruit yield and poor quality of grapes. Furthermore, the weakened state of the vines makes them highly susceptible to environmental stressors, such as frost damage and secondary fungal infections, eventually rendering the vineyard unprofitable.

Currently, there is no cure for vines infected with the Corky bark virus. Therefore, disease management relies entirely on strict preventive measures:

• Planting only certified virus-free nursery stock.
• Implementing rigorous phytosanitary practices during grafting and pruning.
• Controlling populations of mealybugs and other potential insect vectors using integrated pest management.
• Rogueing and destroying infected vines immediately upon diagnosis to minimize secondary spread within the vineyard.