Studies on compatibility of insecticides: Plant oil mixtures against Plutella xylostella (L). in cabbage

The study evaluated the chemical and physical compatibility of insecticide and plant oil mixtures against Plutella xylostella on cabbage. Pongam, Castor and Sesamum oils were examined in conjunction with Emamectin benzoate 5% SG, Indoxacarb 14.5% SC and Spinosad 2.5% SC. Co-toxicity coefficients (CC), which measure chemical compatibility, showed synergism in all combinations (CC > 1), with Emamectin benzoate + Pongam oil showing the strongest synergy (CC = 1.61). The pH range of the mixture was 5.5 to 6.5, indicating chemical stability. However, phase separation and sedimentation caused incompatibility, as determined by the jar test, which measures physical compatibility. Physical instability restricts the direct tank-mix application, even with powerful synergistic effects. These findings highlight the potential for developing improved formulations, supporting resistance management and sustainable control of P. xylostella in cabbage ecosystem.