Fusarium surface rot of sweet potato

The causative agent of Fusarium surface rot is the fungus Hypomyces ipomoeae. This disease is a significant post-harvest fungal infection that affects the root systems and tubers, often leading to substantial losses during the storage and marketing phases of sweet potato production.

The primary host for this pathogen is the sweet potato (Ipomoea batatas). The disease specifically targets the storage roots, making it a critical concern for producers aiming to preserve the quality and commercial value of their harvest over extended periods.

The symptoms of the infection typically appear as small, circular, slightly sunken lesions on the surface of the root. As the disease progresses, these lesions become dry, corky, and brown. In high humidity environments, a white to light pink mycelial growth of the fungus may emerge on the infected surfaces of the tubers.

Development and spread of the fungus are heavily influenced by environmental factors such as poor ventilation and high humidity in storage facilities. Any mechanical damage to the periderm (skin) of the sweet potato serves as an entry point for the pathogen, particularly when the crop is subjected to suboptimal storage temperatures.

The economic impact of this rot is significant, as it renders the affected roots unmarketable and susceptible to further decay. Since infected tubers can serve as a reservoir for spores, the rot can spread rapidly throughout a storage crate, potentially destroying entire batches if not managed proactively.

Effective prevention and control strategies include:

• Implementing careful harvesting techniques to minimize skin nicks and cuts.
• Performing a proper curing process after harvest to allow periderm suberization and wound healing.
• Maintaining optimal storage conditions with controlled temperature and adequate airflow.
• Regularly sorting stored crops to remove and destroy any symptomatic tubers immediately.
• Practicing strict sanitation within storage units to prevent the buildup of fungal spores.