Cercospora leaf spot of beans

Cercospora zonata

Cercospora zonata (Citrus Canker):

Appearance:

Cercospora zonata is a bacterial pathogen that primarily affects citrus plants, causing a disease known as citrus canker. It is characterized by the development of lesions on leaves, fruit, and stems. These lesions typically have a corky appearance, and they may be raised, blister-like, and surrounded by a water-soaked margin. The lesions can vary in size and shape, and they often have a distinctive ring-like or zonal pattern, giving rise to the name "Cercospora zonata."

Identification:

Identifying Cercospora zonata involves recognizing the characteristic symptoms on citrus plants. The lesions on leaves, fruit, and stems are the primary diagnostic features. The presence of a zonal pattern and water-soaked margins on these lesions distinguishes citrus canker from other citrus diseases. Confirmatory diagnosis may involve laboratory tests such as culturing the bacterium or molecular techniques.

Management:

Managing Cercospora zonata, or citrus canker, involves a combination of cultural, chemical, and quarantine measures to prevent its spread. Here are some common management strategies:

  1. Quarantine Measures: Infected plants should be promptly removed and destroyed to prevent the further spread of the disease. Quarantine zones may be established to restrict the movement of infected plants.

  2. Copper-based Sprays: Copper-based fungicides and bactericides are commonly used to manage citrus canker. These treatments are often applied as protective measures, especially during periods of high disease pressure.

  3. Pruning: Prune and remove infected plant parts to reduce the source of inoculum. Proper disposal of pruned material is essential to prevent further contamination.

  4. Cultural Practices: Implementing good cultural practices, such as maintaining proper spacing between citrus trees, providing adequate nutrients, and optimizing irrigation practices, can contribute to plant health and reduce susceptibility to the disease.

  5. Resistant Varieties: Planting citrus varieties that show some resistance to Cercospora zonata can be a preventive measure.

  6. Sanitation: Regularly clean and disinfect tools and equipment used in citrus groves to prevent the mechanical spread of the pathogen.