J.N.L. Lamptey, O.A. Danquah, O.O. Okoli, P.P. Frimpong-Manso, C.Osei, E. Moses
Seven exotic varieties of cassava developed at IITA, Ibadan, Nigeria and three local varieties were evaluated for tolerance to cassava anthrcnose disease (CAD) in five ecological zones of Ghana. The trials were conducted at Crops Research Institute, Fumesua (Forest Zone) in 1988, 1989,1990; Aiyinase (High Rain Forest Zone), Pokuase and Ohawu (Coastal Savanna Zone), Ejura (Forest-Savanna Transition Zone) in 1989 and 1990; Techiman (Forest-Savanna Transition Zone); Nyankpala and Damongo (Guinea Savanna Zone) in 1990. In 1997, 15 exotic varieties were evaluated together with two local varieties at Fumesua, Ohawu and Ejura. CAD damage at six months after planting were scored on a 5- point scale based on the severity of the disease. The disease occurred in all the ecological zones but seventy varied from one eco-zone to the other. The exotic varieties were significantly more tolerant to CAD than the local varieties in areas of high disease pressure like Fumesua and Ohawu in 1988, 1989 and 1990. In 1997, however, CAD severity on the exotic varieties was not signficantly different from the local varieties. The disease was moderately severe on both exotic and local varieties. Greater research effort is needed to develop more resistant varieties to improve the quality of planting materials and root yield.