Avocado anthracnose

Causative agent and type of disease
Avocado anthracnose is a significant fungal disease caused by the pathogen Colletotrichum perseae. It is classified as an ascomycete fungus and is known globally as a primary cause of post-harvest rot and leaf spotting in avocado production areas, significantly impacting the fruit industry.

Affected crops
The primary host for Colletotrichum perseae is the avocado tree (Persea americana). While the most visible damage occurs on mature fruit, the fungus is capable of infecting other parts of the plant, including leaves, stems, twigs, and flowers, thereby negatively impacting the plant's overall photosynthetic capacity.

Symptoms and signs of infection
Infection on fruit typically manifests as small, dark, circular spots that gradually expand. As the disease progresses, these spots become depressed, necrotic lesions. In humid conditions, a characteristic mass of pinkish or grayish conidia (spores) appears on the surface of the lesions. Internally, the flesh beneath the spot becomes discolored, decayed, and develops a bitter taste, making the fruit completely unmarketable.

Conditions for development and spread
The pathogen thrives in warm, humid climates, particularly where heavy rainfall occurs during the fruit-set and maturation phases. Spores are dispersed through water splashes from rain or irrigation systems, as well as by wind. The disease often remains latent in the fruit while it is green, only becoming active as the fruit ripens and its physiological resistance decreases.

Economic impact and protection measures
This disease is a major cause of post-harvest losses. Effective management requires a combination of cultural and chemical methods:

• Implementing strict sanitation by removing and destroying dead wood and mummified fruit.
• Ensuring proper orchard hygiene and pruning to promote good air circulation within the canopy.
• Applying preventive fungicide sprays during the flowering and fruit development stages.
• Maintaining optimal cold chain conditions post-harvest to slow down the development of latent infections.