Isolation, Identification and Pathogenicity of Fungi Associated with Cocoyam (Colocasia esculenta) Spoilage

Abstract

Cocoyam (Colocasia esculenta) corms, purchased from a local barn in Awka, Anambra state, showing spoilage symptoms were examined for rot associated with fungal pathogens. The spoilage organisms were isolated from the corms by explanting the spoilt tissues obtained aseptically onto Sabouraud Dextrose Agar supplemented with chloramphenicol an antibacterial agent. The developing isolates were purified by repeated subculture and identified macroscopically and microscopically using the slide culture technique. The organisms recovered from spoilt cocoyam were Aspergillus niger, Rhizopus stolonifer, Mucor circinelloides, Penicillium cyclopium and Fusarium oxysporum. The rot due to Rhizopus, Mucor and Fusarium were extensive resulting in complete maceration of cocoyam tissues. The pathogenicity test also showed that the above organisms were responsible for cocoyam spoilage. These spoilage organisms may have had access into these cocoyam corms through air, wounds, working equipment (for harvesting) and pests. Proper care should be taken in the handling of these corms as some of these spoilage fungi are known to have negative impact on both humans and livestock because they produce mycotoxins.