Bacterial spot

Pathogen: Xanthomonas arboricola pv. pruni is a bacterium that causes bacterial spot, a significant disease affecting stone fruit trees, including peaches, plums, cherries, and apricots.

Symptoms:

1. Leaf Lesions:

   • Water-Soaked Lesions: Initial symptoms include small, water-soaked lesions on leaves.
   • Lesion Appearance: Lesions progress to have a dark center with a yellow halo.

2. Fruit Lesions:

   • Spots on Fruit: Fruits may develop small, raised spots with a dark center.
   • Cracked and Sunken Areas: Severe infections can lead to cracked and sunken areas on the fruit.

3. Stem Lesions:

   • Canker-Like Lesions: The bacterium may cause canker-like lesions on stems, affecting overall plant health.

4. Leaf Drop:

   • Premature Leaf Drop: Severe infections can result in premature leaf drop, affecting the tree's vigor.

Identification:

• Water-soaked lesions on leaves with a dark center and yellow halo.

Conditions Favoring Disease:

1. Warm and Wet Conditions:
   • Bacterial spot thrives in warm and humid environments.
   • Rain or irrigation facilitates bacterial spread.

Management:

1. Copper-Based Sprays:

   • Protective Sprays: Application of copper-based sprays during the growing season can help manage bacterial spot.

2. Sanitation:

   • Remove Infected Material: Promptly remove and destroy infected leaves, fruits, and branches to reduce bacterial inoculum.

3. Avoid Overhead Irrigation:

   • Drip Irrigation: Use drip irrigation to minimize water on foliage, as wet conditions favor bacterial spread.

4. Resistant Varieties:

   • Plant Resistant Cultivars: Select stone fruit varieties that are resistant or less susceptible to bacterial spot.

Note: Bacterial spot caused by Xanthomonas arboricola pv. pruni can lead to significant losses in stone fruit production. Implementing a combination of cultural practices, sanitation, and, when needed, copper-based sprays is crucial for disease management.