Bacterial canker

Pseudomonas syringae, Pseudomonas morsprunorum

Pathogen: Pseudomonas syringae is a Gram-negative bacterium that encompasses various pathovars (pathogenic varieties) capable of infecting a wide range of plant species. Different pathovars of Pseudomonas syringae are associated with specific diseases in various plants.

Common Pathovars:

  1. Pseudomonas syringae pv. syringae:

    • Causes Bacterial Brown Spot: Affects a variety of plants, causing water-soaked lesions on leaves and stems.

  2. Pseudomonas syringae pv. tomato:

    • Causes Bacterial Speck and Spot of Tomato: Affects tomato plants, leading to specks on leaves and spots on fruits.

  3. Pseudomonas syringae pv. phaseolicola:

    • Causes Halo Blight of Beans: Affects beans, causing water-soaked lesions with a halo-like appearance.

Symptoms:

  • Lesions: Symptoms often include water-soaked lesions on leaves, stems, and sometimes fruits.
  • Discoloration: Lesions may progress to brown or black discoloration.
  • Halo Effect: Some pathovars cause a characteristic halo effect around lesions.

Conditions Favoring Disease:

  1. Warm and Wet Conditions: Pseudomonas syringae thrives in warm and humid environments.
  2. Rain or Irrigation: Moisture on leaves and stems from rain or irrigation facilitates bacterial spread.

Management:

  1. Cultural Practices:

    • Sanitation: Remove and destroy infected plant material to reduce the source of inoculum.
    • Crop Rotation: Rotate crops to prevent the buildup of bacteria in the soil.

  2. Bactericides:

    • Copper-Based Bactericides: Application of copper-based bactericides can help control bacterial diseases.

  3. Avoid Overhead Irrigation:

    • Drip Irrigation: Use drip irrigation instead of overhead sprinklers to minimize leaf wetness.

  4. Resistant Varieties:

    • Plant Resistant Cultivars: Choose plant varieties that are resistant or less susceptible to the specific pathovar causing the disease.

Note: Different pathovars of Pseudomonas syringae have specific host ranges, and their impact varies. Management strategies may need to be tailored based on the specific pathovar and the affected crop.

Plant Protection Products