Effect of some essential oil and methanol extract of aromatic medicinal plants on bacterial wilt pathogen Ralstonia solanacearum

Essential oil and methanol extract of fourteen aromatic/medicinal plants were tested for their antibacterial properties against Ralstonia solanacearum. Inhibition zone technique (bacterial cells amended/seeded in medium) was used to screen the methanol extract/essential oils at four concentration viz., 0.25, 0.50, 0.75 and 1.00 mg botanicals. All essential oils (seven) from aromatic plants were found effective at 1.00 mg concentration with significantly more inhibition zone in comparison to other concentrations of botanicals. Oil from Mentha piperata restricted the bacterial growth to 9.42 mm and was found statistically superior to others i.e. palmarosa (8.42 mm), geranium (8.00 mm), M. arvensis (7.83 mm), citronella (7.75 mm), M. spicata (7.50 mm) and lemon grass (7.17 mm) at the highest concentration of botanicals. Out of eleven methanol extract of aromatic/medicinal plants only three (palmarosa, M. arvensis, and M. longifolia) were found effective. Maximum inhibition zone (38.00 mm) was recorded with palmarosa leaf extract followed by M. longifolia (13.50 mm) and M. arvensis (15.33 mm) at 1.00 mg botanical concentration.