Nematicidal activity of essential oils from aromatic plants of Morocco

Essential oils (EOs) from Moroccan ecotypes of Artemisia herba-alba, Citrus sinensis, Rosmarinus officinalis and Thymus satureioides and their main components were comparatively evaluated for their in vitro activity against the phytonematode species Meloidogyne incognita, Pratylenchus vulnus and Xiphinema index. Suppressiveness of drench or fumigation soil treatment with the four EOs was also investigated against M. incognita on tomato in potting mixes. The in vitro nematicidal activity of the main constituents of the four EOs was also determined. More than 94 % mortality of M. incognita juveniles occurred after a 24-h exposure to a 15 mu g ml(-1) solution of A. herba-alba EO. A 100 % mortality of X. index females was observed at all exposure times and concentrations of all EOs except that from C. sinensis. Mortality of P. vulnus peaked at 75 % only after a 96-h permanence in the 15 mu g ml(-1) solution of R. officinalis EO. The in vitro activity of EOs' main components was never as high as that of the whole EOs, suggesting a synergistic action of the EO multicomponent mixture. Soil treatments with the four EOs generally resulted in a significant reduction of root-knot nematode infestation on tomato, though in an aggregate comparison of data the A. herba-alba EO was more active than the other three EOs, and fumigation treatments were more effective than application in water solution. The high nematicidal activity of most of the tested EOs and their large availability make them a potential source of new nematicide formulations.