Phomopsis cane and leaf spot

Phomopsis viticola

Phomopsis viticola:

Phomopsis viticola is a fungal pathogen that causes Phomopsis cane and leaf spot, a common disease affecting grapevines (Vitis vinifera). This disease is prevalent in many grape-growing regions, and it can lead to significant yield losses if not properly managed. Here's an informative description of Phomopsis viticola, including its appearance, identification, and management:

Appearance:

Cane Symptoms:

  1. Cankers: Phomopsis viticola infects young shoots and canes, causing the development of small, dark lesions or cankers. These cankers may have a raised appearance.
  2. Fruit Rot: Infections can extend into the clusters, leading to berry rot and reduced fruit quality.
  3. Pycnidia Formation: Small, black structures known as pycnidia may be visible on infected canes, especially during wet conditions.

Leaf Symptoms:

  1. Leaf Spots: Infected leaves may develop small, dark spots with a reddish or purplish border.
  2. Leaf Curling: Severe infections can cause the curling and distortion of leaves.
  3. Premature Defoliation: In advanced stages, infected leaves may prematurely drop from the vine.

Identification:

  1. Cane Inspection: Regularly inspect grape canes for the presence of dark lesions or cankers, particularly during the growing season.
  2. Leaf Examination: Check grape leaves for the characteristic spots, curling, or distortion, especially on the upper side of the leaves.
  3. Fruit Inspection: Examine grape clusters for signs of berry rot, which may be associated with Phomopsis viticola infection.
  4. Pycnidia Presence: During wet conditions, the formation of small, black pycnidia on infected canes may be visible with the naked eye or a magnifying glass.

Management:

  1. Pruning Practices:

    • Prune Infected Canes: Prune and remove canes showing symptoms of Phomopsis viticola during dormant pruning to reduce overwintering inoculum.

  2. Fungicide Application:

    • Fungicidal Sprays: Application of fungicides, especially during critical periods of grapevine growth, can help manage Phomopsis viticola. Timing is crucial, and it should be based on local recommendations and weather conditions.

  3. Cultural Practices:

    • Canopy Management: Promote good air circulation within the grapevine canopy through proper training and pruning practices.
    • Avoid Overhead Irrigation: Minimize moisture on plant surfaces, as wet conditions favor the development and spread of the fungus.

  4. Resistant Varieties:

    • Plant Resistant Grape Varieties: Consider planting grape varieties that are known to be more resistant or tolerant to Phomopsis viticola.

  5. Sanitation:

    • Remove Infected Debris: Remove and destroy infected canes, leaves, and debris from the vineyard to reduce the source of inoculum.

  6. Regular Monitoring:

    • Scout for Symptoms: Regularly monitor grapevines for symptoms of Phomopsis cane and leaf spot, especially during periods conducive to disease development.