Pseudocercospora leaf and fruit spot

Pathogen and disease type: The causal agent of this disease is the fungus Pseudocercospora angolensis. It is a serious fungal infection that primarily compromises the health and productivity of various citrus species, leading to significant physiological stress in the host plant.

Affected crops: The pathogen primarily affects plants within the Citrus genus. Susceptible cultivars include sweet oranges, lemons, and grapefruits, with the disease being a major limiting factor for citrus production in specific tropical regions of Africa.

Symptoms and signs: The infection manifests as necrotic spots on the leaves, usually surrounded by a distinct yellow halo. Fruit symptoms include dark, sunken lesions that distort the peel's surface, often leading to premature fruit abscission and severe economic loss for growers.

Conditions for development and spread: The fungus thrives in environments characterized by high humidity and moderate temperatures. The spread of conidia is facilitated by rain splashes and wind, making the disease particularly difficult to contain during the rainy season or in poorly ventilated orchard setups.

Harmfulness and protection measures: The disease causes massive fruit drop and reduces the marketability of harvested produce. Management strategies emphasize the following:

• Pruning and removing infected branches.
• Using certified healthy planting material.
• Applying preventive copper-based fungicides.
• Implementing orchard sanitation practices.
• Monitoring weather patterns to time fungicide applications effectively.