Nematicidal efficacy of isothiocyanates against root-knot nematode Meloidogyne javanica in cucumber

Isothiocyanates (ITCs), a series of new nematicides of the –NCS group, were evaluated for their efficacy against root-knot nematode Meloidogyne javanica. Of the compounds tested, AllylITC, AcITC, EtITC, BzTC, BzITC, 1-PEITC and 2-PEITC showed in vitro irreversible nematicidal activity against second-stage juveniles of M. javanica, following exposure for 72 h at concentrations as low as 5 μg mL−1. When exposed to AllylITC, AcITC and EtITC at lower concentrations, motile juveniles also became irreversibly immobile in 3 days, with a LC50 value at 2.76, 2.53 and 3.05 μg mL−1, respectively. In the pot experiments, 1.0 ml AllylITC and 1.1 ml AcITC per kg of soil controlled M. javanica, similarly to or better than metam sodium at its recommended dose. Similar results were obtained in the field experiments using 1.0 kg AllylITC or 1.0 kg AcITC ha−1. Based on the results of this study, AllylITC and AcITC have potential to be used as new bio-fumigant nematicides.

Research highlights
► The nematicidal efficacy of isothiocyantes (ITCs), a series of new nematicidal agents of the –NCS group, were first evaluated against the root-knot nematode Meloidogyne javanica.
► Most ITCs showed nematicidal activity against knot-root nematode in vitro, especially AllylITC and AcITC. The toxicity of AllylITC and AcITC varied significantly with concentration, but there were no significant differences between AllylITC and AcITC against root-knot nematode at any rate. Therefore, it is recommended that when using AllylITC or AcITC as nematicidal agents, they be applied at 1.0 and 1.1 kg ha-1, respectively.
► Furthermore, Allyl-ITC could be obtained by Myr-catalyzed hydrolysis of the endogenous GL sinigrin from A. rusticana (889 μmol g−1). This compound exhibits very little or no toxicity to non-target organisms, and easy to apply by farmers.