Colletotrichum kahawae

Colletotrichum kahawae is a specialized fungal pathogen belonging to the Kingdom Fungi. It is the primary causal agent of Coffee Berry Disease (CBD), one of the most destructive diseases affecting Arabica coffee (Coffea arabica). This pathogen poses a constant threat to global coffee production, causing severe economic losses in affected regions.

The disease primarily attacks green berries, causing necrotic lesions that rapidly turn black. Infected berries usually shrivel and mummify, often falling off the plant. In severe outbreaks, the pathogen can also infect flower buds and young shoots. The loss of reproductive tissues leads to a dramatic decrease in marketable yield, making early detection vital for plantation management.

The biological cycle of the fungus is characterized by the production of conidia within acervuli on the surface of infected berries. These spores are disseminated primarily by rain splash and high-velocity wind-driven water droplets. Upon contact with a host, the conidia germinate, produce an appressorium, and penetrate the host cuticle to begin internal tissue colonization.

Environmental factors are critical for the spread of Colletotrichum kahawae. The fungus thrives in cool to moderate temperatures ranging from 18°C to 25°C and requires high relative humidity or frequent rainfall for spore germination and infection. Dense coffee canopies that trap moisture create an ideal environment for the pathogen to establish and proliferate throughout the season.

Effective management and control strategies involve a multi-pronged approach:

• Cultural control via proper pruning to improve air circulation and reduce micro-humidity.
• Sanitation by removing infected berries to reduce the primary inoculum load.
• Application of preventative fungicides, such as copper-based formulations, during the critical flowering and fruit-setting stages.
• Development and cultivation of CBD-resistant coffee varieties to provide long-term protection.