Field Evaluation of Selected Botanicals and Carbofuran for Nematicidal Activity against Plant-parasitic Nematodes Associated with Kenaf (Hibiscus cannabinus L.)

This study assessed the nematicidal potential of selected botanicals on predominant species of plant-parasitic nematodes (PPNs) infecting kenaf in the early and late rainy season of 2023, Ibadan, Nigeria. A naturally PPN-infested field with 5 years consecutive kenaf cropping history was ploughed and harrowed. The layout of the experimental plots was arranged in 2 x 12 factorial in RCBD with three replicates, with each plot measuring 2.5 m by 1.4 m. Air-dried and milled leaves of Chromolaena odorata, Azadirachta indica, Hyptis suaveolens, Ficus exasperata and Tithonia diversifolia were applied at 0.18 kg m-2 and 0.36 kg m-2 at the stem base of plant stands, at 2 weeks after planting, while carbofuran at 3 kg ha-1 was used as a treated control due to the established knowledge of its nematoxicity. Ten weeks after planting, the plants were harvested and data collected on dry fibre yield (core and bast) and soil nematode population. An analysis of variance was performed on the data, using the SAS Statistical application 2002 version. Fisher’s LSD was applied at 5% level of probability. Nematode data were square root-transformed before subjecting to analysis. Each of the botanicals at the both doses was effective in suppressing populations of PPNs, including Meloidogyne spp., Helicotylenchus spp., and Pratylenchus spp., in the early and late rainy season. This successful pest suppression led to a consequent increase in core and bast fibre yield. These findings emphasize the need to explore the use of botanicals to reduce farmers’ dependence on synthetic nematicides.