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.

Fluopyram: Optimal Application Time Point and Planting Hole Treatment to Control Meloidogyne incognita

“…As fluopyram is reported to be systemically active and moves through the plant acropetally (Bayer CropScience,), and as already described that a minimum concentration of 16 mg/L of fluopyram is required for a significant reduction of sedentary Meloidogyne javanica in tomato roots, there may be a systemic effect [25]. However, a similar experiment was done using a smaller soil volume, and it studied nematode infection in the root system by staining the nematodes in infected roots over time (Figure 3 A,B).…”

“…Because the low water solubility and strong affinity of fluopyram to soil particles typically reduces movement into the upper 10 cm soil layers [16], we hypothesize that a targeted application of fluopyram in the planting hole will have reduced side effects on beneficial organisms and the soil microbial community [25,26]. Furthermore, a wide field application of fluopyram may not have sufficient RKN control, since RKN populations are found in similar amounts at both 0-30 cm and 30-60 cm soil depths [27], generally where plant roots and moist soil are present [28].…”

Bioisosterism and Scaffold Hopping in Modern Nematicide Research

“…However, most of them were eliminated gradually because of their environment and food safety risks . For example, methyl bromide was phased out in 2005, although some OP and carbamate nematicides, such as fosthiazate and oxamyl, still occupy a large part of the nematicide market. , These two classes of nematicides might be prohibited in the future as a result of their high toxicity. Avermectin has become the mainstream nematicide at present.…”