Isolation and Pathogenicity Effect of Fungi on Varieties of Cocoyam Corms.

Cocoyam (Colocasia esculenta) is an important food crop that had been utilized in several localities. Fungal spoilage of cocoyam corms has always been a post-harvest problem for farmers. Apart from the loss caused to farmers, final consumers are exposed to infectious agent s, which are capable of causing fungal infection through spores. This study was undertaken to evaluate the pathogenicity effect of fungi associated with the spoilage of varieties of cocoyam corms. Spoilt and healthy (normal) samples of cocoyam were purchase at Uli Market, Anambra State. The spoilt samples were evaluated for the presence of food spoilage fungal species using Sabouraud Dextrose Agar (SDA) and Potato Dextrose Agar (PDA). The healthy cocoyam samples were used to perform pathogenicity test using two varieties of cocoyam (yam-like cocoyam and jelly-like cocoyam’ otherwise known as ede ji and ede uli, respectively). The fungal isolates were characterized based on their cultural features and microscopy. The cultured samples yielded four fungal species with variation in frequency of occurrence viz; Aspergillus niger (42.5%), Aspergillus flavus (25%), Aspergillus fumigatus (20%), and Rhizopus arrhizus (12.5%). Also, the variety of cocoyam that was mostly infected was the yam-like species and the pathogenicity test confirmed that the isolates were capable of reducing the weight of health cocoyam after 3 days of exposure. Having ascertained that these fungal species are plant pathogens, preventive and control methods are essential to ensuring that food shortage caused by the agents is minimized.