Colletotrichum constrictum

Pathogen and disease type. The fungus Colletotrichum constrictum is a known causative agent of anthracnose, a severe fungal disease that impacts plant health globally. As a hemi-biotrophic pathogen, it first infects living tissues before transitioning to necrotrophic growth, causing rapid tissue breakdown and colonization of the host by producing conidia within acervuli structures.

Affected crops. This pathogen exhibits a broad host range, primarily targeting members of the Solanaceae family and various ornamental plant species. It is also documented on certain horticultural crops where it poses a significant threat to yields, especially in regions with consistent environmental suitability for fungal growth.

Symptoms and signs. Typical symptoms include localized sunken lesions on stems, foliage, and fruits. These lesions often appear as dark, water-soaked spots that eventually darken and expand, leading to necrotic tissue death. A distinctive sign during humid conditions is the presence of glistening, slimy masses of spores, which usually appear in hues ranging from light pink to orange, emerging from the center of the lesions.

Conditions for development and spread. The fungus thrives in warm and humid environments, with the optimal temperature range typically falling between 20°C and 28°C. High relative humidity and prolonged periods of leaf wetness are critical factors that facilitate spore germination and host penetration. Dissemination occurs mainly through splashing water, overhead irrigation, contaminated tools, and infected seeds.

Protection and prevention measures. Effective management requires a multifaceted approach:

• Implementing strict sanitation practices by removing and destroying crop debris after harvest.
• Utilizing disease-free, certified seeds and resistant cultivars whenever possible.
• Optimizing spacing and irrigation methods to improve air circulation and reduce leaf wetness.
• Applying systemic and contact fungicides (such as strobilurins or triazoles) based on monitoring and disease pressure forecasts.