In-vitro nematicidal efficacy of aqueous leaf and root extracts from indigenous Ghanaian plants on Meloidogyne incognita egg hatch

Abstract

Meloidogyne incognita is a devastating pest in the tropics which parasitises a wide range of crops, leading to economic damage. This study evaluated the in-vitro efficacy of aqueous leaf and root extracts from Tagetes erecta (African marigold), Moringa oleifera, and Solanum macrocarpon (Gboma) against M. incognita egg hatch. A 3 × 2 × 5 factorial experiment in a Completely Randomised Design (CRD) was conducted with three replicates across five concentrations (0, 10, 25,50 and 100% w/v). Daily counts of second-stage juveniles (J2) were recorded over 14 days. The study revealed significant main effects and a strong three-way interaction (P < 0.001), indicating that egg hatch inhibition was influenced by plant species, plant part, and extract concentration. All botanicals showed potent, concentration-dependent inhibition, with undiluted (100%) extracts reducing egg hatch, by over 95%, compared to the control. Probit dose-response modelling identified M. oleifera leaf extract as the most effective, with an estimated EC50 of 3.56% w/v (95% CI: 2.78 - 4.39%), followed by S. macrocarpon leaf extract (EC50 = 4.91% w/v). Notably, leaf tissues exhibited superior ovicidal activity relative to roots at comparable low doses. These findings support the potential application of M. oleifera and S. macrocarpon aqueous leaf extracts as eco-friendly bio-nematicide for sustainable management of M. incognita.