ANTI-MILDEW ACTIVITY OF METHANOLIC EXTRACT FROM SELECTED MEDICINAL PLANTS AGAINST PLASMOPARA HALSTEDII (FARL.) BERL. & DE TONI INCITANT OF SUNFLOWER DOWNY MILDEW DISEASE

Abstract

Methanolic extracts of eight medicinal plants were screened for their anti-mildew activity against Plasmopara halstedii, incitant of downy mildew of sunflower. Extracts of Morinda citrifolia, Zingiber officinale, and Tinospora cordifollia were found to be best in reducing the sporulation of P. halstedii in both the whole leaf and leaf disc method. Further; the phytochemical analysis of these extracts revealed the presence of alkaloids, glycosides, steroids, flavonoids, reducing sugars, phenolics, tannins, saponins and terpenoids. Different compounds from the plant extracts were partially purified through preparative thin layer chromatography and analyzed for their anti-mildew activity following leaf disc method. The assay confirmed that bioactive compound from M. citrifolia (Rf,  0.47), Z. officinale (Rf, 0.6) and T. cordifollia (Rf, 0.12) were antimildew in nature. In vitro sporangiosporicidal assay revealed that, partially purified antimildew compounds significantly reduced the viable sporangiospores and also inhibited the release of sporangiospores from sporangia.