IDENTIFICATION AND MOLECULAR CHARACTERIZATION OF STAGONOSPOROPSIS CUCURBITACEARUM CAUSES GUMMY STEM BLIGHT DISEASE ON COCCINIA GRANDIS- A FIRST REPORT IN KARNATAKA, INDIA

Gummy stem blight caused by Stagonosporopsis cucurbitacearum (syn. Didymella bryoniae) is one of the major disease in cucurbits. The goal of the study is to identify and characterize S. cucurbitacearum causing gummy stem blight in Coccinia grandis. The infected samples collected from the C. grandis growing fields, surface sterilized and inoculated on PDA medium. The morphology of the inciting pathogen was thoroughly studied. For further confirmation, the molecular characterization was done by using PCR amplified DNA product with specific ITS1 and ITS4 - rDNA primers and sequenced for further analysis. Phylogenetic tree was constructed using nBLAST data, which confirmed that the pathogen as S. cucurbitacearum. The isolate was deposited in the GenBank and accession number was obtained (OL774656, OL774657, and OL774658). The pathogenicity test was carried out on detached fruit assay on ivy gourd. The characteristic symptoms on fruits and re-isolation also confirmed presence of S. cucurbitacearum. In vitro evaluation of fungicides and plants extract against pathogen was carried out, the results showed that, Kavach (34.66±0.33 at 1.0 mg L -1), effectively inhibit the growth followed by Indofil, Aliette, Sectin, and Nativo. Likewise, the methanol extract of Neem and Ficus exhibits significant inhibitory activity. Therefore, this study revealed S. cucurbitacearum responsible for causing gummy stem blight disease in C. grandis host and this is the first report in Mysuru of Karnataka, India. Further the effective management is required to minimize the disease incidence and yield loss of this high nutritional vegetable crop.