Morphological Characteristics of Colletotrichum Species Associated with Mango (Mangifera indica L.) in Southwest Ethiopia

Abstract

Anthracnose of mango caused by Colletotrichum species is among the numerous diseases causing low production and quality of mango fruit in Ethiopia. The objectives of this work were to identify and characterize Colletotrichum species isolates responsible for anthracnose of mango in Southwest of Ethiopia. Samples of infected mango leaves, panicles and immature fruits were collected from home gardens of nine districts in Southwestern part of Ethiopia. Among them eight isolates of Colletotrichum species with distinct morphology on PDA were observed in each group. Colony color, shape and diameter of every culture were recorded, conidial size and shapes were computed from 20 conidia per isolate. The results showed that Colletotrichum species isolates were grouped into three distinct morphological types: Colletotrichum gloeosporioide morph type I (37%) with hyaline cylindrical conidia rounded both ends, Colletotrichum acutatum morphotype II (38%) conidia mass in the center and fusiform tapered to a point in both ends, and Colletotrichum asianum morph type III (25%) cylindrical conidia with obtuse to slightly rounded ends.  The length of conidia ranged from 10.5-17.8 μm, width (3.22 to 6.9 μm). Among six media tested, highest mean colony diameter of 51.9 mm was recorded on Potato dextrose agar and the lowest mean mycelial growth of 18.4 mm was recorded on Tap water agar. All isolates had good sporulating capacity on general media. Based on the results of this study, it could be concluded that C. gloeosporioides, C. acutatum and C asianum were found to be the major causal agents of mango anthracnose. Additional study on the epidemiology of anthracnose of mango is needed for further disease management strategies.

Keywords: Anthracnose, Colletotrichum spp., identification, mango, epidemiology