Anthracnose caused by Colletotrichum paxtonii

The causative agent of this disease is the fungal pathogen Colletotrichum paxtonii, a member of the genus Colletotrichum known for causing severe anthracnose infections. This pathogen penetrates plant tissues through natural openings or mechanical wounds, where it begins a destructive process of tissue necrosis, effectively weakening the host plant's vital systems.

The range of hosts for Colletotrichum paxtonii primarily includes various woody and herbaceous ornamental plants, as well as several fruit-bearing species. It typically targets the leaves, stems, and fruits, leading to localized decay that can expand rapidly under favorable environmental conditions, potentially causing significant aesthetic and economic damage.

Symptoms are manifested as sunken, necrotic spots on leaves and stems, often surrounded by a dark, distinct margin. A hallmark of this infection is the development of acervuli—small fungal fruiting bodies—within the center of the lesions. Under high humidity, these produce masses of spores, often appearing as slimy, pinkish-orange drops, which serve as the primary inoculum for further spread.

The development and spread of Colletotrichum paxtonii are heavily dictated by moisture availability, as spores are dispersed primarily by water splashes, rain, and irrigation. It thrives in warm, humid climates where the infection cycle can repeat multiple times throughout a single growing season, making it a persistent challenge in damp agricultural environments.

Effective management and prevention of the disease require a comprehensive approach to break the infection cycle. Key practices include:

• Strict sanitation by removing and destroying all infected plant debris.
• Maintaining proper plant spacing to ensure adequate air circulation and reduce humidity.
• Applying preventive fungicide treatments, particularly during wet weather cycles.
• Selecting certified, disease-free planting material to prevent initial infestation.