Efficacy of aqueous extracts of rhizophora mangle l. bark in the management of meloidogyne incognita on okra

Meloidogyne incognita (MI) contributes to yield losses in okra worldwide. Rhizophora mangle (RM) has been used in the management of insects, but not on MI. A pot experiment was laid out in completely randomized design to determine the effects of aqueous bark extracts of RM and carbofuran on MI-infected okra. Meloidogyne incognita-infected okra plants were treated with RM aqueous extracts of 20%, 10%, 5% weight per volume (w/v) and carbofuran 3 kg. a.i./ha one week after inoculation (WAI). Data were collected on growth parameters fortnightly till 8 WAI. At 8 WAI, data were collected on fruit weight, fresh shoot and root weights, dry shoot weight, Gall index, nematode population and reproductive factor; and were appropriately analyzed. Rhizophora mangle at 20% w/v compared favourably with carbofuran in terms of growth and yield of treated okra. Okra treated with carbofuran and RM at 20% w/v had significantly higher fresh and dry shoot weight, and fruit yield than infected-untreated okra. Rhizophora mangle at varying concentration levels and carbofuran reduced gall index, nematode population and reproductive factor of MI in treated okra significantly (p<0.05) compared to infected-untreated okra. Efficacy of RM extract was concentration dependent in the order of 20% w/v >10% w/v >5% w/v. Aqueous bark extracts of RM especially at 20% w/v promises to be an effective environment-friendly nematicide in the management of M. incognita-infected okra.