Hypomyces ipomoeae

Hypomyces ipomoeae is a specialized ascomycete fungus and a significant plant pathogen known for causing decay and rot in sweet potato (Ipomoea batatas) and related plant species. Within the botanical and agricultural community, it is identified as a causative agent of surface root rot, which can severely compromise both the quality and shelf-life of harvested tuberous roots.

Taxonomically, the fungus is classified within the Hypocreales order, Hypocreaceae family. Its life cycle involves both asexual reproduction, producing conidia that facilitate rapid spread during the growing season, and sexual reproduction, which contributes to long-term survival in the environment. These survival structures allow the fungus to remain latent in the soil for several years, waiting for suitable host tissue.

The infection process typically begins when fungal spores enter through wounds on the root surface, often caused during cultivation, harvest, or handling. Once established, the fungus colonizes the cortex of the root, resulting in necrotic lesions. These lesions may appear as discolored, sunken areas that slowly expand, leading to tissue degradation. Under high humidity, a white to pinkish mycelial growth can be observed covering the symptomatic areas.

Environmental conditions play a critical role in the severity of the disease. Hypomyces ipomoeae thrives in warm, moist soils and environments with poor ventilation. High humidity levels inside storage facilities provide the ideal conditions for the pathogen to spread from infected roots to healthy ones, potentially leading to total loss of a storage batch if not managed correctly.

Effective management and control strategies focus on minimizing inoculum levels and preventing infection. Key measures include maintaining a strict crop rotation schedule, ensuring that planting material is certified disease-free, and avoiding any mechanical damage to the roots during harvesting. Post-harvest storage management, particularly rapid curing and maintaining optimal temperature and humidity, is essential to prevent secondary infections and ensure marketability.