Bio-efficacy of different formulations of chlorantraniliprole 0.53%+ fipronil 0.8% GR against yellow stem borer of rice

The study was conducted during rabi (December, 2020-May, 2021), and kharif (July-December, 2021) at University Instructional Farm, UBKV, Pundibari, Cooch Behar, West Bengal, India with a new combination of insecticides Chlorantraniliprole 0.53% w/w and Fipronil 0.8% w/w GR with different formulations to evaluate the bio-efficacy of these combinations of insecticides against yellow stem borer (Scirpophaga incertulas). In this study three formulations of Chlorantraniliprole 0.53% w/w+Fipronil 0.8% w/w GR @ 5.63 kg ha⁻¹, @ 7.50 kg ha⁻¹ and @ 9.38 kg ha⁻¹ were used and Chlorantraniliprole 0.40% GR @ 1 kg ha⁻¹, Fipronil 0.3% GR @ 25 kg ha⁻¹, Cartap hydrochloride 4% GR @ 18.75 kg ha⁻¹ and untreated control were evaluated against yellow stem borer in rice crop. The result suggested from the present investigation that Chlorantraniliprole 0.53%+Fipronil 0.8% GR @ 7.50-9.38 kg ha⁻¹ was found best and effective as well as at par with each other against rice yellow stem borer. It has been observed that Chlorantraniliprole 0.53%+Fipronil 0.8% GR @ 9.38 kg ha⁻¹ registered good yield, 4.81 t ha⁻¹ and 4.72 t ha⁻¹ which were on par with Chlorantraniliprole 0.53%+Fipronil 0.8% GR @ 7.50 kg ha⁻¹ i.e., 4.79 t ha⁻¹ and 4.70 t ha⁻¹ in two consecutive seasons i.e., rabi, 2020-21 and kharif, 2021 respectively Whereas, Chlorantraniliprole 0.53%+Fipronil 0.8% GR @ 7.50 kg ha⁻¹ found much suitable with effective, safe and favorable cost-benefit ratio. The study also showed that there was no significant difference in density of predators in treated and untreated plots.