Black root and stem rot

Black root and stem rot is caused by the soil-borne fungus Scytalidium, which acts as a destructive pathogen in agricultural ecosystems. This disease specifically targets the vascular system and structural integrity of the plant roots, leading to rapid decay.

The disease is particularly impactful on cassava crops. The fungus invades the starch-storing roots, causing deep tissue necrosis and blackening. This makes the affected tubers unsuitable for market, processing, or human consumption, causing significant economic losses.

Early symptoms include localized dark discoloration on the root surface, which quickly develops into deep-seated black rot. Above-ground symptoms involve wilting, leaf yellowing, and stunted growth as the root system fails to provide necessary support and nutrition to the stems.

The fungus thrives in warm, humid conditions and is persistent in soil, often surviving on decaying plant debris. Spread is primarily mediated by infected planting stakes, contaminated soil movement through farm machinery, or irrigation water carrying fungal spores.

Management strategies focus on integrated pest management practices to reduce inoculum levels in the soil. Since chemical control is often limited, preventive agronomic practices remain the most effective way to safeguard yield and crop health.

• Selecting clean, disease-free planting materials.
• Improving soil drainage to prevent stagnant moisture.
• Practicing crop rotation to reduce soil-borne pathogen populations.
• Sanitizing farm tools to prevent physical spread of the fungus.