Blossom blight

Monilinia laxa

Causal Agent: Monilinia laxa is a fungus that causes brown rot, a destructive disease affecting various stone fruit trees, including peaches, plums, cherries, and apricots.

Symptoms:

  1. Fruit Rot:

    • Brown rot primarily affects the fruit, causing rapid decay and rotting.
    • Infected fruits often develop tan to brown, sunken lesions with a velvety appearance.

  2. Spore Production:

    • The fungus produces masses of powdery spores (conidia) on the surface of infected fruits during humid conditions.

  3. Blossom Blight:

    • In addition to fruit rot, Monilinia laxa can cause blossom blight, where flowers become infected, turn brown, and die.

  4. Twig Dieback:

    • In severe cases, twig dieback and cankers may occur.

Identification:

  1. Brown, Velvety Lesions:

    • Brown, sunken lesions with a velvety appearance on infected fruits.

  2. Powdery Spore Masses:

    • Presence of powdery spore masses on the fruit surface.

Conditions Favoring Disease:

  1. Warm and Humid Conditions:

    • Optimal Growth: The fungus thrives in warm and humid conditions, facilitating spore production and disease spread.

  2. Rain and Splashing Water:

    • Rain and water splashing contribute to the dispersal of spores and initiation of new infections.

Management:

  1. Fungicides:

    • Application of fungicides, especially during the critical periods of bloom and fruit development, is a key component of brown rot management.

  2. Sanitation:

    • Prompt removal and destruction of infected fruits, mummies, and cankers to reduce inoculum.

  3. Pruning:

    • Proper pruning to improve air circulation and reduce conditions favorable for disease development.

  4. Cultural Practices:

    • Good orchard hygiene, including the removal of fallen fruits and debris, helps minimize disease spread.

Note: Brown rot caused by Monilinia laxa can result in significant economic losses in stone fruit production. Integrated disease management, including fungicide applications, cultural practices, and sanitation, is crucial for effective control.