Isolation, Identification and Characterization of Colletotrichum kahawae from Infected Green Coffee Berry in Arsi, Southeastern Ethiopia

Abstract

Colletotrichum kahawae is a causal pathogen of coffee berry disease (CBD). It was reported  in Ethiopia for the first time in 1971. Then spread to all major coffee-producing regions within very short period. It was prevalent in most coffee growing areas of Ethiopia and has been characterized in Morpho-cultural attributes. However, characterization of C. kahawae in Arsi has been lacked. Therefore, present study was conducted to characterize C. kahawae isolates for their Morpho-cultural attributes. Those attributes selected for isolates characterization were conducted following procedures and methods collected from recently done researches with few modification. Accordingly, five representative C. kahawae isolates and one C. gloeosprioides were isolated and identified from infected green coffee berry sampled from study areas. Colletotrichum kahawae isolates were characterized for colony color, radial growth rate and texture in case of morphological character, while conidial shape, size and sporulation capacity in case of cultural characteristic. There were significant variation among isolates related their Morpho-cultural features. Four types of colony color were identified as light gray, dark gray, gray and dim gray. Conidia production capacity varied from 7.5×10⁵ – 1.44×10⁶, while conidial size varied among and within isolates ranging from 10.5 to  15.5 µm and 2.78 to 3.83 µm for length and width, respectively. More than 50% of conidial shape frequency of each isolate was under conidial shape of type 1 except isolate Shk9. Except conidial size, other Morpho-cultural attributes has been used for identification of C. kahawae. Therefore,  except conidial size one can be use remaining Morpho-cultural attributes of C. kahawae as diagnosis or identification tools. It means not saying traditional characterization is enough for diagnosis. Since it has limit diagnosis and identification among and within pathogen species, further study should be undertaken via molecular tools.

Keywords: C. kahawae, conidial, colony, Morpho-cultural features.