ABSTRACT
Cocoyam is a very important food item domesticated in many communities across the world, especially Nigeria. Nevertheless, this food product is subject to post harvest damage and invasion of pathogens including fungi. Hence, this study was aimed at evaluating the fungal species associated with the spoilage of cocoyam obtained in Benin City.Fresh healthy cocoyam cormels and cormels with symptoms of post-harvest rot were obtained from a cocoyam barn in a local market. Sterile knife was used to obtain spoilt tissues from the corms, while a portion of the cut-out area is inoculated on PDA plates and were incubated at 270C for four days and then examined daily for fungi growth. The developing cultures were then subcultured. For the pathogenicity test using the healthy cocoyam corms, after washing, the surfaces of the corms were dis-infected with 70% ethanol. A sterile cork-borer was used to bore holes at two spots on the healthy corms while another cork-borer was used to introduce the pure fungi isolates into the holes. Un-inoculated controls which bore no isolate served as control. The cormels were incubated and observed for 14 days. Six fungi isolated from the spoilt cormels were Mucor cercinelloides, Aspergillus niger, Aspergillus fumigatus, Rhizopus stolonifer, Fusarium oxysporum and Penicillium cyclopium. The percentage reduction in weight across the cocoyam samples inoculated with different the fungal pathogens ranged from 49.47 % to 64.66 %, while the control had 3.77 %. In all the isolates, significant changes were observed between day 4 and day 9, except in Penicillium where changes only became noticeable on day 8, and lasted till day 8. These massive reduction in weight of the cocoyam over such a short period will constitute much economic loss to farmers and consumers, should this food product be infected by such organisms. Since cocoyam is a food plant that is consumed by a large population, it should be handled with great care throughout planting, storage, and even cooking. Also, it is important to take aseptic precautions, such as using clean planting equipment, to completely prohibit fungal growth, which can harm consumers.
