Preparation of a benzyl isothiocyanate and furfural based microemulsion formulation for controlling root-knot nematodes (Meloidogyne incognita)

Root-knot nematodes ( Meloidogyne incognita ) are among the most destructive plant-parasitic nematodes worldwide. To develop effective alternatives to chemical nematicides for root-knot nematode control, this study investigated the combined nematicidal activity of benzyl isothiocyanate (BITC), a characteristic secondary metabolite of cruciferous plants, and furfural (Fur), a compound derived from hemicellulose-rich agricultural byproducts. Bioassays revealed that BITC exhibited high contact toxicity (LC₅₀ = 15.37 mg·L - ¹), whereas Fur demonstrated high fumigant activity (LC₅₀ = 0.55 μL·L - ¹). The binary combination of BITC and Fur at an LC 50 ratio = 2:8 demonstrated a synergistic effect in terms of fumigant activity, with a co-toxicity coefficient (CTC) of 226.65. Based on this ratio, an approximately 1:1 active-ingredient mass ratio was obtained after conversion, and a 20% BITC-Fur microemulsion (ME) was subsequently formulated using BITC and Fur as the active ingredients. Quality analysis indicated that the 20% BITC-Fur ME formed a transparent, single-phase, homogeneous yellowish-brown liquid with high stability. In pot trials, the control efficacy of the 20% BITC-Fur ME against M. incognita reached 88.57% and 91.42% at 50 days post-fumigation at dosages of 200 and 800 mg a.i. (active ingredient) kg - ¹ , respectively. Field trials conducted in 2024 and 2025 demonstrated efficacies of 77.37% and 76.47%, respectively, at 60 days post-fumigation with a dosage of 12 g a.i. m −2 . These findings demonstrate that the binary combination of BITC and Fur exhibits enhanced efficacy against M. incognita , positioning the 20% BITC-Fur ME as a promising botanical formulation for the management of root-knot nematodes.