Cotton anthracnose

Colletotrichum indicum is a fungal pathogen responsible for cotton anthracnose, a destructive disease affecting cotton crops globally. The fungus belongs to the Ascomycota phylum and specifically targets Gossypium species throughout their life cycle.

The primary hosts of this pathogen are various cotton cultivars. The disease affects the crop at multiple stages, beginning with seedling blight, which can significantly reduce plant density, and progressing to the infection of bolls during the reproductive stage.

Symptoms of Colletotrichum indicum infection include reddish-brown lesions on leaves and cotyledons. When the bolls are infected, small, sunken dark spots appear, which eventually develop a pinkish mass of spores on the surface. This often leads to the internal rot of the cotton fiber.

The disease thrives under conditions of high humidity and moderate temperatures, typically between 22°C and 28°C. The pathogen persists in soil on infected crop debris and is commonly transmitted via contaminated seeds, making seed health a critical factor in preventing outbreaks.

The economic impact of cotton anthracnose is significant due to reduced fiber yield and quality. Infected bolls produce low-grade cotton, and severe seedling blight necessitates costly replanting efforts, disrupting agricultural schedules and reducing overall profitability.

Integrated management strategies for controlling the disease include:

• Rigorous seed treatment with chemical fungicides to eliminate seed-borne inoculum.
• Implementation of crop rotation cycles to reduce the persistence of the fungus in the soil.
• Deep plowing of field residues to encourage microbial decomposition of the pathogen.
• Management of irrigation to prevent water stagnation and excessive canopy humidity.
• Foliar applications of fungicides during periods of high disease pressure.