Black sigatoka

Pathogen and disease type. Black sigatoka is a severe fungal disease affecting banana plants, caused by the ascomycete Pseudocercospora fijiensis (formerly Mycosphaerella fijiensis). This disease is classified as a leaf spot infection and remains the most economically significant threat to global banana production.

Host plants. The primary hosts are plants of the genus Musa, including commercial dessert bananas, plantains, and various ornamental banana cultivars. Most high-yield commercial varieties are highly susceptible to this pathogen, making it a critical concern for tropical agriculture.

Symptoms and signs. The infection begins as tiny, pale streaks on the underside of leaves, which gradually lengthen and turn dark brown or black. These spots often develop a yellow halo. As the disease progresses, large areas of the leaf tissue become necrotic, leading to premature drying and wilting of the leaves, which significantly impacts the plant's health.

Development and spread. The fungus thrives in warm, humid conditions with temperatures between 25°C and 28°C and high rainfall. Spores are primarily dispersed by wind and splashing water droplets. The pathogen enters the leaf through stomata, and high humidity is essential for the germination of spores and the subsequent colonization of the host tissue.

Harmfulness and control measures. Black sigatoka causes a drastic reduction in the photosynthetic capacity of the plant, resulting in smaller fruit, poor fruit quality, and uneven ripening. Management strategies involve:

• Regular application of systemic and contact fungicides.
• Sanitation, including the systematic removal of heavily infected leaves.
• Proper spacing to improve air circulation within the plantation.
• Planting of resistant or tolerant banana hybrids.