Colletotrichum tropicale

Colletotrichum tropicale is a destructive fungal pathogen belonging to the Colletotrichum gloeosporioides species complex. It is primarily recognized as the causal agent of anthracnose, a disease that causes severe damage to a wide range of economically significant tropical and subtropical crops, leading to significant yield losses globally.

The host range of this fungus is remarkably broad, encompassing perennial tree crops such as cacao, coffee, mango, and avocado, as well as several leguminous species. The pathogen is capable of infecting all aerial parts of the host plant, including leaves, stems, inflorescences, and fruit, often causing necrotic lesions that significantly reduce both the quality and quantity of the harvest.

Symptoms typically manifest as small, water-soaked spots that eventually enlarge into dark, sunken necrotic lesions. In humid conditions, the pathogen produces characteristic acervuli, which appear as creamy or pinkish masses of conidia on the surface of the lesions. Infected tissues often wither, and severe infections can lead to tip dieback, premature leaf drop, and total decay of the fruit.

The spread and development of Colletotrichum tropicale are heavily dependent on climatic conditions. High humidity and rainfall are critical for the dispersal of conidia, which are usually spread by water splash, wind, or human activity. Warm temperatures ranging from 22°C to 28°C provide the optimal environment for the pathogen to germinate and invade the host tissues efficiently.

Management of this disease requires an integrated approach to mitigate its impact. Key strategies include:

• Strict sanitation by removing and burning infected plant debris.
• Implementing proper pruning techniques to increase light penetration and air circulation.
• Using certified disease-free seedlings for establishing new plantations.
• Applying protective fungicides during flowering and fruit development stages to prevent infection.