Potential of Cleome viscosa L for the management of rootknot nematodes Meloidogyne incognita in okra Abelmoschus esculentus L Moench

Studies were conducted to determine the reaction of root-knot nematode, (Meloidogyne incognita) to Cleome viscosa and to assess the use of C. viscosa as a bionematicide in okra. Fifty eggs and juveniles of M. incognita were separately exposed to extracts from shoot and root of C. viscosa plants. Egg hatch and juvenile mortality were observed for ten days. Pots with okra plants inter-planted with 0, 2, 4 and 8 cleome/pot were inoculated with 2,500 and 5,000 M. incognita eggs. Soil in the pots containing seedlings of okra was inoculated with 5,000 eggs of M. incognita and treated with 0, 12.5, 25 and 37.5 g/pot of dried shoot powder, and with carbofuran applied as control. Data were taken on growth, yield, galling index, population of nematodes and reproductive factor. Nematode egg hatch was inhibited by 91% in shoot extracts of cleome while juvenile mortality in the extracts was 100% after four days of exposure. C. viscosa roots showed symptoms of galling at inoculation density levels of 2,500 and 5,000 nematodes per pot. However, C. viscosa shoot powder encouraged better plant growth and reduced nematode populations in okra. Phenols, alkaloids, tannins and terpenoids were present in C. viscosa with higher amounts in shoots. Inter-planted C. viscosa plants sustained populations of root-knot nematodes and their combined effect suppressed the growth of okra while the powder was nematicidal and improved growth of okra.