Variations among the populations of Colletotrichum species from diseased coffee berries were studied. A total of 35 Colletotrichum isolates representing 24 districts from major coffee producing regions of Ethiopia were studied on the basis of cultural, morphological and pathological characteristics. Isolates differed on their colony color, density, sector and acervuli. Mycelial growth rate varied significantly (p<0.05) among the isolates and ranged between 3.97 and 8.69 mm/day. Sporulation capacity, conidial length (12.3-17.7 μm) and conidia width (3.6- 5.1μm) also varied significantly (p<0.05) among the isolates. The dominant forms of conidia were cylindrical and round at both ends followed by cylindrical acute at one and round at the other ends. Cluster analysis based on cultural, morphological and pathological characteristics showed that Colletotrichum species associated with diseased coffee berries fell into three distinct groups and were identified as C. kahawae, C. gloeosporioides and C. acutatum. Among these fungal isolates, only C. kahawae was pathogenic to both detached coffee berries and coffee hypocotyls tested. The other Colletotrichum species exist as saprophytic or sequential colonizer of dead tissues. In conclusion, our study indicates the existence of variation in cultural, morphological characteristics and pathogenicity among the C. kahawae and the other related Colletotrichum isolates. Studies at the molecular level should be conducted to determine the genetic diversity of the coffee berry disease (CBD) pathogen populations in the country.

Keywords: CBD, Colletotrichum kahawae, genetic diversity, pathogenicity, variation