CHAPTER ONE
INTRODUCTION
Cocoyam (Colocasia esculenta) is widely cultivate and used for food in Nigeria, Ghana and other countries including China.  China and Ghana leading in world production (Onwueme and Charles, 1994).
Although its production has increased from 643000 to 1.7 million tones during the past decade, its contribution to root-crop production increased from only 39-6.8% (Agboola, 1979). In Nigeria, Colocasia species are the most important food and the third most important root/tuber crop after yams and cassava (Onwueme, 1978). Besides critical contribution to the national food security and cash  income  producing nations, cocoyam  are also being considered as source of starch for use in biodegradable film materials and for other industrial and pharmaceuticals purposes because of interesting properties of the amylopectin fraction of starch, which is the principal form of cocoyam starch (cecil, 1992).
Cocoyams have very short post harvest storage life of a few days to weeks (Gollifer and Boot, 1973, Ugwunwanyi and Obeta, 1997). Differing and often conflicting reports have been made on the post harvest losses of cocoyam. But it bears nothing that post harvest storage life is often short and biodegradative losses are extensive and up to 100% losses are common due to the fungi which associates with the spoilage of cocoyam during storage condition,  (Onwueme and Charles, 1994),
However, substantial post harvest losses caused  by the fungi associated with the spoilage  of cocoyam tubers during storage is attributed to a number of physical, physiological damage  arising  from harvesting, storage or transportation have  often been implicated as some of the predisposing factors  to cocoyam spoilage or deterioration (Ogundana et al;1970, Snowdon, 1991). Invasion by pathogens either through natural openings or wounds is considered the most critical factor in cocoyam spoilage (Degras, 1993).
A wide range of micro-organisms (Particularly moulds) have been associated with cocoyam decay, relatively few are implicated as primarily pathogens (Aderiye and Ogundana, 1984). The degree of pathogenicity varies and is highly dependent upon storage conditions. It has been stated that fungi take the lead in the spoilage of cocoyam during storage. (Nwufo and Atu, 1987). Under these storage conditions, the fungi which are liable to  attack cocoyam include; Fusarium  solani, Botryodiplodia, theobromae, Rhizopus, stolonifer, Aspergillus  niger, Sclerotium roltsii, Trichoderma hamatum and Pythium species. (Nwufo, 1980,Uwgunwanyi and Obeta, 1996). Another factor also attributed to the spoilage of cocoyam is high respiratory activity. Storage temperature to an optimum of 70C and 85% relative humidity increases the storage time. The crops are usually left in the ground and harvested when need, and there  is a limit to how long the crop can be left in the soil since the corms and cormels sprout and produce new growth, which result  in the cocoyam losing its good values.