PRE AND POST HARVEST STUDIES OF YAM DISEASES AND THEIR CONTROL MEASURE IN SOUTH EASTERN NIGERIA

Yam, (Dioscorea spp) is the most important food crop and source of income for millions of producers, processors and consumers in West Africa. In Nigeria, its production is constrained by many problems such as high cost of production, nematodes attack, vertebrate pests and pathogens singly or in combination. They are all responsible for field suppression and tuber quality deterioration in storage. Though yam tuber naturally has a periderm, microorganism that cannot get into, it is easily wounded by rodents, nematodes and man during field operation including weeding, harvesting and post-harvest handling. The wounds make room for the penetration and development of rot microorganism. The magnitude of these problems has made many to express fear that yam production in Nigeria may decline substantially in the near future. Due to all these problems of yam during pre and post-harvest, there should be a thorough control measure for both farmers and scientists to mitigate loss of yams both in the field and in the store (Barn). Some research has been conducted to test the potency of some plant extracts for the control of yam tuber rot caused by Fusarium oxysporum, Aspergillus niger and Aspergillus flavus. It was found that hot water extracts were obtained from leaf and seed of uda (Xylopia aethiopica) and Ginger (Zinigiber officinale), and were found during harvest, to be fungi-toxic against the fungi