Horticultural Science and TechnologyISSN:1226-8763(Print) 2465-8588(Online)원예과학기술지

The objective of this study was to evaluate the antimicrobial activities of 9 kinds of medicinal plants against crown gall in grapevine. The medicinal plants extracted with several solvent systems were screened for in vitro antibacterial activity by the disc diffusion method. The ethanol and ethyl acetate extracts from magic lily flowers, tachys roots, asian plantain flowers and seeds, sweet wormwood leaves, stems and flowers, immature bitter melon fruits, cockscomb flowers, and peach tree resin showed in vitro antimicrobial activities against Rhizobium vitis with growth inhibition zones ranging from 10 to 27 mm in diameter. The minimum inhibitory concentration values of extracts against R.vitis ranged from 10,000 in Asian plantain flower and 50,000 fold diluted extracts in sweet wormwood flowers, stems, leaves, cockscomb leaves and immature bitter melon fruits. The active fractions of ethyl acetate and ethanol extracts from the medicinal plants were partially separated through silica gel column chromatography and thin layer chromatography (TLC). The active fractions were separated at Rf 0.36, 0.69, 0.75, 0.84, and 0.94 in sweet wormwood extracts, Rf 0.96 and 0.99 in cockscomb flower extracts, Rf 0.92 and 0.97 in cockscomb leaf extracts, and Rf 0.85 in immature bitter melon fruit extracts in TLC analysis developed with hexane:ethyl acetate (20:80, v/v) and methanol:chloroform (20:80, v/v). Among extracts from plants with in vitro antimicrobial activities, sweet wormwood, cockscomb leaves, and immature bitter melon fruits showed in vivo antimicrobial activities with inhibition activity of 100, 67, and 83.3%, respectively, in ‘Kyoho’ grapevine inoculated with R. vitis compared with the untreated control. These findings indicate that extracts of medicinal plants could be used as sustainable candidates to control crown gall disease caused by R. vitis in grapevines.