Comparison of a vintage and a recently released nematicide for the control of root-knot nematodes and side effects on two entomopathogenic nematodes

Abstract

Root-knot nematodes can cause tremendous losses in vegetable crops. Farmers usually rely on synthetic nematicides to protect their crops. Recently, newly released nematicides are giving farmers an alternative in chemical control for nematodes. In the present study, the efficacy of vintage nematicide was compared to that of a relatively new nematicide, fluopyram. The latter was always more effective in substantially lower concentrations than oxamyl. Fluopyram paralyzed more than 80% J2s after 24 h immersion at the concentration of 0.25 µL L−1, while the percentage was increased close to 100% after immersion for 48 and 96 h. Similar levels of dead J2s were observed after immersion of J2s in oxamyl at concentrations higher than 8 µL L−1 (24 and 48 h) or 4 µL L−1 (96 h). An evident decrease of egg differentiation was observed when fluopyram concentration was increased to 8 µL L−1, while no significant decrease in egg differentiation was recorded at any concentration of oxamyl. Egg hatching was decreased at concentrations of fluopyram higher than 4 µL L−1, while no reduction was observed even when the concentration of oxamyl was increased to 64 µL L−1. The efficacy of fluopyram in soil was superior compared to that of oxamyl. For the first time, the systemic action of fluopyram is recorded in trials with tomato plants. On the other hand, compared to oxamyl, fluopyram seems to be more toxic to non-target organisms such as the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis bacteriophora.