Comparative efficacy of some selected chemicals and biopesticides against diamond backmoth (Plutella xylostella L.) on cabbage (Brassica oleracea var. capitata)

Eight treatments viz., T₁ (NSKE 5%), T₂ (Spinosad 45 SC 0.35 ml/L), T₃ (Emamectin Benzoate 5% SG 0.5 g/L), T₄ (Neem oil 5% 50 ml/L) T₅ (Tobbaco leaf extract 5% 40 ml/L), T₆ (Imidacloprid 18% SL 1 ml/L), T₇ (Beauvaria bassiana 1 × 10⁸ CFU) and T₈ (control) were evaluated against diamond back moth, Plutella xylostella (L.). Each insecticide was sprayed twice at 15 days interval. The larval population per 5 plants was recorded day before and 3, 7 and 14 days after each spray. The lowest larval population was observed in T₂ Spinosad 45 SC 0.35 ml/L (2.86) (2.45) at both sprays, followed by T₃ Emamectin benzoate 5% SG 0.5 g/L (3.06) (2.67), T₄ Neem oil 5% 50 ml/L (3.85) (3.26), T₅ Tobacco leaf extract 5% 40 ml/L (3.90) (3.47), T₁ NSKE 5% (4.07) (3.74), T₆ Imidacloprid 17.8% SL 1 ml/L (3.83) (3.35), T₇Beauvaria bassiana 1 × 10⁸ CFU (3.72) (3.47) and control (5.27) (6.63). The highest crop yield and CBR were recorded from T₂ Spinosad 45 SC 0.35 ml/L [(74.53 t/ha) and (1:3.3)] respectively, followed by T₆ imidacloprid 17.8% SL [(68.18 t/ha) and (1:2.98)], T₅ Tobacco leaf extract 5% SG [(60.4 t/ha) and (1:2.6)], T₃ Emamectin benzoate 5% SG [(52.72 t/ha) and (1:2.2)], T₄ Neem oil 5% [(48.15 t/ha) and (1:2.1)], T₇Beauvaria bassiana 1 × 10⁸ CFU [(37.53 t/ha) and (1:1.7), T₁ NSKE 5% [(30.18 t/ha) and (1:1.3)] and T₈ control [(25.82 t/ha) and (1:1.0)].