Assessment of Plant Growth Responses and Root-Knot Nematode Control Using Three Pesticides with Diverse Action Mechanisms

This study evaluated seed treatment with emamectin benzoate, fosthiazate, and thiacloprid as an alternative to soil application for managing Meloidogyne incognita in tomato plants grown in clay and sandy soils under greenhouse conditions (30 ± 5°C). Pesticides were applied at 200, 400, 600, and 1000 ppm, and effects on seed viability, vegetative growth (germination, shoot, and root length), and nematode development were assessed at 7, 14, and 21 days. Emamectin benzoate exhibited the least phytotoxicity, maintaining up to 100% germination at 400 ppm in clay soil, with shoot/root lengths significantly greater than other treatments. Thiacloprid caused the greatest reductions in germination (down to 20% at 600 ppm in clay) and growth, especially in sandy soil. Nematode infestation parameters (nematode count, gall and egg mass numbers) were significantly suppressed by emamectin benzoate, which reduced nematode numbers by 49.13%, galls by 73.85%, and egg masses by 31.55% at 1000 ppm in clay soil. Fosthiazate showed moderate control, while thiacloprid was least effective. Nematode reproduction factor (RF) values were consistently lower in clay soil, with emamectin benzoate reducing RF from 2.34 to 1.75 at 7 days (200 to 1000 ppm). Sandy soil exhibited higher nematode pressure and reduced pesticide efficacy, likely due to leaching. Statistical analysis confirmed significant interactions between soil type, pesticide, and concentration. Overall, emamectin benzoate is recommended for nematode management in tomato, particularly at higher doses and in clay soils, to optimize both nematode suppression and seedling growth .