Morpho-molecular characterization of causative agents of wilting, leaf spot, fruit blight and stem canker of okra (Abelmoschus esculentus L.)

This study aimed at identification and characterisation of the wilting, leaf spot, stem canker and fruit-blight diseases of okra. Pathogen infected plant samples were sterilised with 2% sodium hychlorite solution for 20 mins and then cultured at 28 °C for 15 days followed by microscopic examination. Combined microscopic, morphological and cultural characteristics analyses identified the four okra fungal isolates (OFI) such as OFI-1, OFI-2, OFI-3 and OFI-4 as Fusarium oxysporum, Curvularia lunata, Fusarium chlamydosporum and Choanephora cucurbitarum, respectively. The isolates OFI-1, OFI-2, OFI-4 showed highest radial growth rates at 25 °C, pH 5 and 20% lactose containing media while it was sucrose for OFI-3. BLASTN search using the sequence of ITS regions revealed that OFI-1, OFI-2, OFI-3 and OFI-4 isolates had 98, 100, 97 and 100% homology with F. oxysporum, C. lunata, F. chlamydosporum and C. cucurbitarum, respectively. Pathogenicity tests were also confirmed by reproducing the disease symptoms in okra plants.