In-vitro bioassay of organic nematicides against Root-knot nematode, Meloidogyne incognita (Kofaid & White). Chitwood
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Abstract
This study aimed to investigate the efficacy of three essential oils (Neem, Castor, and Garlic oils) and two plant extracts (Datura inoxia and Tagetes patula) in comparison with commercial chemical nematicide (Furadon) under lab conditions. Different doses (1.0%, 1.5%, and 2.0%) of plant extracts/oils were evaluated on egg hatch inhibition and second-stage juveniles (J2s) of the Meloidogyne incognita. Treatments were replicated five times and incubated at ambient temperature. The J2s mortality and percent of egg hatch inhibition were determined after 24, 48, and 72 h. The efficacy increased with the increasing concentration of each extract/oil. Concentrations of 2.0% for Neem oil caused 94.8% inhibition of egg hatching followed by Tagetes patula caused 92.40%. Consequently, all treatments significantly caused mortality of J2s at all three (24, 48, and 72 h) days of exposure as compared to the control-treated with distilled water. The highest mortality was achieved with a 2.0% concentration of Datura inoxia (56.40%) followed by Tagetes patula (53.40%). The concentrations of extract/oils at 1.5% and 2% were found more efficient against nematodes when compared to lower 1.0%. From these results, this study results confirm that the nematicidal activity may be due to the presence of phytotoxic compounds in these extracts/oils. These findings could be useful for further isolation and characterization of nematicidal compounds present in these plants and they may provide a baseline for the identification of new organic nematicides.
Keywords: Meloidogyne incognita; In-vitro bioassay; Plant extracts; Essential oils