Nematicidal activity of Verbesina encelioides against the root-knot nematode Meloidogyne javanica and effects on plant growth

Background and aims Many nematicidal compounds with a variety of chemical structures have been isolated from various plant families, particularly the Asteraceae. Nematicidal activity of Verbesina encelioides (Asteraceae) was tested against the root-knot nematode Meloidogyne javanica. Methods Nematicidal activity of V. encelioides extracts, fresh plant parts and their respective powders was tested against M. javanica in in-vitro and pot experiments. Results Aqueous extracts of the fresh flower showed the strongest nematicidal activity, followed by leaf and stem extracts. The number of viable nematode juveniles in soil was greatly reduced by mixing in dry and fresh flowers or leaves at concentrations of 0.1 and 1.0%, respectively. A powedered V. encelioides leaves added to nematode-infested soil at a concentration of 0.2% decreased root-galling index and the number of nematode eggs on roots. The nematicidal compound (s) in the flower and leaf could be extracted in water, methanol and ethanol, but not in acetone, ethyl acetate or n-hexane. The plant was found to be a non-host to M. javanica, M. incognita and M. hapla. Conclusions Verbesina encelioides might serve as a green manure or its extracts as a nematicides for the control of root-knot nematodes.