Nematicidal activity of various aqueous extracts against root-knot nematodes (Meloidogyne chitwoodi)

Abstract

In this study, twelve aqueous extracts were assessed for their effects on egg hatching, mortality of second-stage juveniles (J2s) of Meloidogyne chitwoodi in vitro and growth chamber in 2020-2021. The mortality of the J2s increased with increasing exposure time and concentration with all extracts. Maximum mortality was observed in 10% extracts of Anethum graveolens (100%), Eruca sativa (100%), Vitex agnus-castus (98%), Asphodelus aestivus (96.4%), Eucalyptus camaldulensis (95.6%) after 24 hours and minimum mortality was found in 1% extracts of Laurus nobilis (6.6%) after 6 hours. Maximum suppression of hatching was found at 64.2%, 61.0%, and 59.4% with extract of A. aestivus, Nerium oleander, V. agnus-castus after 7 days, respectively. The pot experiments showed that gall index was the lowest in soils treated with Ficus carica, N. oleander, Zingiber officinale, and L. nobilis. The chemical composition of four aqueous extracts was analysed by using GC-MS, and the main components of L. nobilis, E. camaldulensis, F. carica, and N. oleander were identified as eucalyptol, 2-methoxy-6,10-dimethyl-dodeca-2E,6Z,10Z-trienoic acid, 12-acetoxy-, and dihydroedulan II. The study confirms the potential of mainly L. nobilis, E. camaldulensis, F. carica, and N. oleander extracts for the formulation of new products for controlling M. chitwoodi.