RESUMEN
Fungal decay of yam (Dioscorea alata) popularly known as water yam bought from Nsukka Markets in Nigeria was investigated for the fungi responsible for postharvest rot of tubers in storage. The tubers were used to isolate and identify fungal species that cause rot and deterioration of tubers in storage. A total of seven fungi namely Botryodiplodia theobromae, Aspergillus sp, Aspergillus niger, Fusarium spa, Fusarium sp, Penicillium sp and Trichoderma sp were isolated from healthy or sound tubers. Pathogenicity test was done and proved for all the isolates with Botryodiplodia theobromae and Penicillium sp implicated as the most pathogenic while Trichoderma sp was the least pathogenic. Inoculated tubers were examined and the nature of the rot varied with the pathogens.Fungi