RESPONSE OF ARSI COFFEE COLLECTIONS TO COFFEE BERRY DISEASE (Colletotrichum kahawae) AT GOLOLCHA AND MECHARA, OROMIA REGIONAL STATE, ETHIOPIA

Abstract

Coffee Berry Disease which caused by Colletotrichum kahawae, is a major constraint to the cultivation of African Arabica coffee. In Ethiopia, it alone caused about a 24-30% loss of the national average yield on local landraces. Ethiopia mainly uses resistant varieties and mechanical and cultural disease management strategies. However, still, there is a lack of improved and resistant varieties development in a few coffee growing areas including Arsi Zone. The objectives of this study were to investigate the resistance of Arsi coffee collections to Coffee Berry Disease through artificial inoculation of green berries on mother trees, younger coffee seedlings under controlled conditions, and detached berries under laboratory conditions. The field experiment was conducted at “Gololcha Arbagugu” farm state and Mechara Agricultural research center on station. A hypocotyl test and detached berry test were conducted at Jimma Agricultural Research Center and Haramaya University respectively. Field and detached berry inoculation tests were carried out on 13 Arsi coffee collections and the Coffee Berry Disease - susceptible Arusa coffee variety. Standard checks like susceptible variety (370) and resistant varieties 741 and 754 were used for hypocotyl tests. Seventeen treatments were used for hypocotyl tests. There was a significant difference in Coffee Berry Disease reaction levels among genotypes (P< 0.001) under field conditions. The infection percentage of berries varied from 2.89 to 25.93% at Arsi and 3.25 to 34.92 % at Mechara three weeks after treatment applications. The results of this study revealed highly significant (P < 0.001) differences in the percentage of coffee berry disease infection among treatments in the detached berry inoculation test. According to the results, the resistant variety 741 showed the lowest infection percentage (15.04 %) in comparison to all other collections and/or varieties at the seedling stage. Therefore, coffee collections that showed the lowest level of infection percentage under all experimental conditions (Ar15/11, Ar05/11, and Ar70/11) were recommended for further breeding strategies.