Melia azedarach controls Meloidogyne incognita and triggers plant defense mechanisms on cucumber

Melia azedarach fruit extracts have recently raised a substantial interest for their use in crop protection against phytoparasitic nematodes. The effect of M. azedarach on the root-knot nematode Meloidogyne incognita on cucumber, as well as the effect on the plant deference mechanism, is reported herein. Crushed fruits of M. azedarach, tested in the soil at the rates of 30 and 60 g kg 1, exhibited nematicidal activity similar to the one of fenamiphos (0.02 g a.i. kg 1) in terms of nematode population in roots and soil as well as reproduction rate. M. azedarach water extracts, rich in aldehydes, alcohols and carboxylic acids, showed nematicidal activity against M. incognita. Moreover, all M. azedarach treatments decreased the activities of catalase (CAT) and peroxidase (POX) involved in host H2O2 detoxification. Soil application of M. azedarach fruits could be favourably considered in the control of M. incognita on cucumber in a sustainable agriculture, since they act directly as nematicidals. Furthermore, M. azedarach elicits plant defence and helps the host to fight the nematodes infestation in an indirect way.