Abstract Mangoes are an important source of vitamins all over the world. However, their production has been endangered by Colletotrichum gloeosporioides that causes anthracnose of mangoes. This study was aimed at isolating the fungus from infected mangoes followed by testing the sensitivity of the fungus to essential oils from eucalyptus, sage and rosemary plant. Infected mango fruits were acquired from Njokerio Market near Egerton University. Fungal pathogens were isolated from the infected fruits using potato dextrose agar. Essential oils were extracted from eucalyptus, sage and rosemary plant using distillation method. Sensitivity of Colletotrichum gloeosporioides to the extracted essential oils was carried out using agar well technique. The colonies of Colletotrichum gloeosporioides had dense whitish mycelium with black and orange color fruiting bodies. The spores were smooth, hyaline and sub cylindrical with round end spores. The conidia were cylindrical in shape, hyaline in colour and the size was 13.4 – 24 x 4.0 – 5.9µm. The appresoria were obovate to clavate in shape, brown in colour and 6.7 – 19.8 x 3.8 – 11.9µm in size.There was a relationship between heating time and yield of essential oils in rosemary (r=0.99) and leaves (r=0.99). Conversely, there was no significant difference in the percentage yield of essential oils from eucalyptus, sage and rosemary (P=0.057). There was no significant difference in the percentage composition of the different compounds in the essential oils extract from eucalyptus, sage and rosemary (F=0.48 P=0.62). The zone of inhibition of essential oils obtained from eucalyptus against Colletotrichum gloeosporioides varied from 19±3mm to 21±1mm, sage (18±1mm-19±2mm) and rosemary (17±1mm-19±1mm). The minimum inhibition of essential oils from eucalyptus leaves was120±0.01mg/ml, sage (241±0.00mg/ml) and rosemary (230±0.02mg/ml). The minimum fungicidal concentration of essential oils from eucalyptus was (120±0.01mg/ml), sage (241±0.00) and rosemary (230±0.02). The essential oils from eucalyptus, sage and rosemary have bioactive compounds that have antifungal properties againstColletotrichum gloeosporioides.
Keywords Colletotrichum gloeosporioides, Essential oils, Eucalyptus globules, Mangoes, Salvia officinalis, Rosmarinus officinalis.