Colletotrichum simmondsii

Colletotrichum simmondsii is a significant fungal plant pathogen belonging to the Kingdom Fungi. As a member of the genus Colletotrichum, it is widely recognized as a primary causative agent of anthracnose in various berry crops, most notably strawberries. It is a highly aggressive fungus capable of causing severe yield losses in both open-field and greenhouse production systems.

The disease manifests through various symptoms, including necrotic, sunken lesions on fruits, petioles, runners, and crowns. On mature fruit, these lesions are often covered in gelatinous, salmon-colored spore masses. This fungal attack not only destroys the fruit quality but also weakens the entire plant, often leading to total crop failure if left unmanaged.

The life cycle of this pathogen is highly dependent on environmental conditions. Colletotrichum simmondsii overwinters in crop debris or the soil as mycelium or sclerotia. During the growing season, spores (conidia) are dispersed primarily by rain splash and overhead irrigation. It can infect plants latently, meaning symptoms may not appear until conditions become favorable for fungal growth.

Development is favored by warm, humid weather, typically ranging from +20°C to +30°C. High humidity and surface wetness are essential for spore germination and colonization. In intensive strawberry production, the dense canopy architecture often creates a microclimate that exacerbates the disease pressure, allowing the fungus to spread rapidly across the field.

Integrated pest management (IPM) is essential for effective control.

• Selection of resistant cultivars and disease-free nursery stock.
• Implementation of drip irrigation to reduce canopy wetness.
• Strategic use of protective and systemic fungicides during high-risk periods.
• Removal of infected plants to minimize the inoculum source in the field.