The incidence of fungal leaf spot diseases on mango (Mangifera indica) in Oda Bultum University Mango farm and application of fungicide and a biological control measure was investigated. In addition microbial biocontrol and fungicide control against C. gloeosporioides developed for mangoes has been less reported in Ethiopia. Common mango disease control mechanisms in Ethiopia are utilization of pesticides. However, pesticides are overused and misused. As a result there is an urgent need to reduce the use of synthetic chemicals. Biological control offers an alternative to the use of pesticides. Invitro evaluation and testing of T. harzianum showed maximum mycelial growth inhibition (74.4% and 73.5%) on C. gloeosporioides isolates 1 and 3 respectively. The minimum percent of mycelial growth inhibition (71.5%) of T. harzianum was observed on isolate 1. Pseudomonas fluorescens showed maximum mycelial growth inhibition on isolate 2 (74.1%), followed by isolate 1 (70.4%). Least percent of mycelial growth inhibition by P. fluorescens was observed on isolate 3 (69%). B. subtilis showed maximum mycelial growth inhibition on isolate 3 (56.1%), followed by isolate 1 (51.5%). Least percent of mycelial growth inhibition by B. subtilis was observed on isolate 2 (48.6%). In vitro evaluation of fungicides against the three isolated test pathogen revealed that at 1000 PPM, all fungicides showed highest percentage inhibition (72.8% to 90.14%). The highest percentage inhibition was observed at the concentration of1000 PPM on isolates 2 (90.14%) and 3 (88.13%) and the lowest percentage inhibition was observed at the concentration of 200 PPM on isolates 1 (71.46%) and 3 (77.18%). The highest percentage mycelial growth inhibition by Sancozeb 80% WP on the isolates was 90.14% at a concentration of 1000PPM, whereas the lowest percentage mycelia growth inhibition of 83.06% was recorded at 200PPM. The highest percentage mycelial growth inhibition by Ridomil on the isolates was (83.16%) at 1000 PPM and the lowest percentage mycelial growth inhibition was recorded on isolate 1 (72.83%) at 200 PPM. Among the two fungicides Sancozeb was the most effective fungicide to inhibit the growth of the isolates with 87.98-90.14% inhibition.

Keywords: Biocontrol, Colletotrichum gloeosporioides, Epiphytes, Mango, Leaf Spot, in Vitro, Mycelial Growth, Microbial Antagonists