Sorghum anthracnose

Pathogen and disease type. Sorghum anthracnose is a fungal disease caused by the pathogen Colletotrichum caudatum (often synonymous with Colletotrichum sublineolum). This disease is a significant threat to sorghum production worldwide, affecting the vascular tissue and causing systemic damage to host plants throughout their growth cycle.

Affected crops. The primary host for this pathogen is sorghum, including grain, sweet, and forage types. While it primarily affects cultivated Sorghum bicolor, the pathogen can also survive on various weed grasses, which serve as alternative hosts during off-seasons and contribute to the persistence of the fungus in the field.

Symptoms and signs. The disease manifests as elliptical or irregular lesions on leaves, typically showing a red, purple, or dark brown border. Under humid conditions, the centers of these lesions produce masses of spores known as acervuli, visible as small black dots. Stem infection can lead to internal rotting and lodging, while panicle infection directly impacts grain development and quality.

Conditions for development and spread. Colletotrichum caudatum thrives in warm, humid environments. Frequent rainfall and temperatures between 25°C and 30°C are optimal for spore germination and infection. The pathogen spreads primarily through wind-blown conidia and rain-splashed inoculum, allowing it to move rapidly through a field during the growing season.

Harmfulness and control measures. Anthracnose can cause severe yield losses, especially in susceptible cultivars, by reducing photosynthesis and causing grain rot.

• Deployment of anthracnose-resistant sorghum hybrids.
• Crop rotation to reduce primary inoculum levels in the soil.
• Sanitation practices, including the removal or deep burial of infected stubble.
• Use of fungicide-treated seeds to reduce initial seedling blight.
• Foliar fungicide applications during periods of high humidity and disease pressure.