The two major fungal diseases of rice in Nigeria are rice blast (Pyricularia oryzae Cav.) and brown spot (Cochliobolus miyabeanus (Ito and Kuribayashi) Dreschler ex Dastur). The loss in grain yield attributable to these diseases ranges from 11.5–39.6% and 12–43% respectively, Mancozeb, blasticidin-S, fentin hydroxide, benomyl and edifenphos as foliar sprays effectively control rice blast in the laboratory and field. Brown spot is controlled by spraying with thiram, mancozeb or blasticidin-S. A more useful approach to the control of these diseases being adopted in Nigeria is the search for horizontally resistant varieties. Other fungal diseases of rice in Nigeria are the green smut (Ustilaginoidea virens (Cooke) Tak.), basal sheath rot (Rhizoctonia solani Kühn), sheath blight (Corticium sasakii (Shirai), Matsumoto.), leaf scald (Rhynchosporium oryzae Hashioka and Yokogi), narrow brown leaf spot (Cercospora oryzae Miyake) and bakanae disease, a foot rot caused by Fusarium moniliforme Sheldon. Two suspected cases of virus diseases have been reported; grassy stunt disease (transmitted by Nilaparvata lugens Stal.), and orange leaf disease (transmitted by Inazuma dorsalis (Motschulsky). No bacterial disease of rice has been found in Nigeria.