Feijoa anthracnose

The fungus Colletotrichum feijoicola is the primary pathogen responsible for anthracnose in feijoa plants. This species of the Colletotrichum genus is known for its ability to infect subtropical fruits, leading to necrotic spots and significant agricultural damage. The pathogen survives on plant debris and spreads rapidly through asexual spores called conidia.

The main host for this fungus is the feijoa (Acca sellowiana). While it primarily affects the fruit, causing premature drop and decay, the pathogen can also colonize the leaves and shoots of the plant. If left uncontrolled, the infection can severely weaken the plant, making it more susceptible to other abiotic and biotic stressors.

Visual symptoms typically appear as sunken, dark, necrotic lesions on the surface of the fruit. As the infection progresses, these lesions expand and merge, eventually covering large portions of the fruit. Under humid conditions, orange or pinkish spore masses (acervuli) emerge from these lesions, which is a diagnostic feature used to identify the presence of the pathogen.

The development of Colletotrichum feijoicola is heavily dependent on moisture and temperature. Spore germination and infection are optimal in warm, humid climates with temperatures between 20°C and 25°C. Rain splashing and wind are the primary vectors for local dispersal within a plantation. Poor airflow in dense canopy areas creates a microclimate that drastically accelerates the spread of the disease.

Effective management requires an integrated approach to minimize loss. Sanitation is the most critical step, involving the removal of all infected fruit and twigs from the orchard to reduce the primary inoculum load. Chemical control involves the application of registered fungicides during the flowering and fruit development stages. Additionally, keeping the orchard well-pruned ensures good air circulation and reduces the duration of leaf wetness, effectively lowering the risk of new infections.