Cotton anthracnose fungus

Colletotrichum gossypii is a pathogenic fungus within the Ascomycota phylum, recognized as the primary causative agent of anthracnose in cotton crops worldwide. This pathogen is highly specialized and can infect cotton plants at all growth stages, severely impacting fiber quality and overall crop yields.

The primary symptom of the disease is the development of sunken, dark-colored lesions on cotyledons, stems, leaves, and bolls. As the disease progresses, these lesions produce a pinkish mass of conidia. In severe cases, the pathogen causes seedling damping-off and boll rot, leading to a significant loss of harvest, especially in fiber-producing regions where humidity levels remain high.

The life cycle of the pathogen is centered on its ability to survive in infected crop residues and within the cotton seed itself. Conidia are produced in acervuli and are disseminated primarily by splashing water, rain, wind, and insect vectors. Once they come into contact with a host plant, they penetrate the surface, initiating a new infection cycle.

Favorable conditions for the proliferation and spread of Colletotrichum gossypii include prolonged periods of high humidity (exceeding 85%) and moderate temperatures between 20°C and 28°C. These conditions facilitate the rapid germination of spores and subsequent colonization of host tissues, often leading to widespread epidemics in cotton fields.

Effective management and control strategies for anthracnose involve a combination of cultural and chemical practices:

• Selection of high-quality, disease-free, and fungicide-treated seeds.
• Implementation of crop rotation schemes to break the cycle of soil-borne inoculum.
• Sanitation practices such as the deep burial or burning of infected plant debris post-harvest.
• Application of systemic and contact fungicides during the growing season, specifically when weather conditions favor pathogen development.