Phytochemical and fungicidal activity of selected plant extracts against Phaeoisariopsis griseola of common bea

Abstract

Plant extracts are effective in plant pathogens control and are now becoming popular throughout the world. Allium sativum, Azadirachta indica and Tithonia diversifolia extracts have been reported to exhibit antimicrobial activity against phytopathogens. The aim of this study was to phytochemically screen and determine the fungicidal activity of Azadirachta indica, and Tithonia diversifolia extracts against Phaeoisariopsis griseola of common bean. Phytochemical analysis of the plants and pathogenicity test of Phaeoisariopsis griseola were carried out. Phytochemical screening revealed that alkaloids, tannins, terpenoids, saponins, cardiac glycosides and sterols were present in Azadirachta indica, and Allium sativum while sterols, saponins and alkaloids were absent in Tithonia diversifolia. Flavonoids were present in Allium sativum but absent in Azadirachta indica. All the plant extracts significantly (P≤0.05) decreased spore germination of Phaeiosariopsis griseola in vitro. The most effective was Allium sativum extract and Azadirachta indica at 100% extract concentrations. Tithonia diversifolia had moderate fungicidal effect. This study show that all the plants contain most of the active phytochemical compounds which justify their fungicidal property and extract effectiveness increased with their concentration. Therefore, there is possibility that Azadirachta indica, Allium sativum and Tithonia diversifolia extracts can be used to control Phaeiosariopsis griseola of common bean. Further studies are required to quantify these phytochemicals of these plants for the development of cost effective pesticides for the control of Phaeoisariopsis griseola.