Effect of different insecticides on the whitefly population transmitting YMD in blackgram at different intervals
At all spray schedules, seed treatment (ST) with imidacloprid 600 FS @ 5 ml/kg seed + foliar spray (FS) of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l achieved the highest per cent reduction of whitefly population over the control. After third spray (60 DAS), the results revealed that ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l recorded highest per cent reduction of whitefly population over control (94.10%), followed by ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 30.5% SC @ 0.3 ml/l (87.07%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 70% WG @ 0.2 g/l) (86.66%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of afidopyrofen 5% DC @ 2 ml/l (85.83%). The next best treatments were ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of thiamethoxam 25% WG @ 0.2 g/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of fipronil 5% SC @ 1 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of flonicamid 50% WG @ 0.5 g/l, FS of imidacloprid 30.5% SC @ 0.3 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of dimethoate 30% EC @ 1.7 ml/l and ST with imidacloprid 600 FS @ 5 ml/kg seed, which recorded per cent reduction of 85.39, 83.96, 82.50, 80.95, 80.23 and 41.00 per cent, respectively (Table 2).
At physiological maturity, the results revealed that ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l recorded highest per cent reduction of whitefly population over control (92.07%), followed by ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 30.5% SC @ 0.3 ml/l (85.96%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 70% WG @ 0.2 g/l (85.54%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of afidopyrofen 5% DC @ 2 ml/l (84.44%). The next best treatments were ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of thiamethoxam 25% WG @ 0.2 g/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of fipronil 5% SC @ 1 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of flonicamid 50% WG @ 0.5 g/l, FS of imidacloprid 30.5% SC @ 0.3 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of dimethoate 30% EC @ 1.7 ml/l and ST with imidacloprid 600 FS @ 5 ml/kg seed, which recorded per cent reduction of 83.06, 81.28, 80.58, 78.45, 77.85 and 36.35 per cent, respectively (Table 2).
Effect of different insecticides on the incidence of YMD in blackgram
At all spray schedules, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l recorded the lowest disease incidence. At 60 DAS, the results revealed that ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l recorded lowest disease incidence of 22.23 per cent, followed by ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 30.5% SC @ 0.3 ml/l (25.88%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 70% WG @ 0.2 g/l (26.15%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of afidopyrofen 5% DC @ 2 ml/l (27.35%). The next best treatments were ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of thiamethoxam 25% WG @ 0.2 g/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of fipronil 5% SC @ 1 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of flonicamid 50% WG @ 0.5 g/l, FS of imidacloprid 30.5% SC @ 0.3 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of dimethoate 30% EC @ 1.7 ml/l and ST with imidacloprid 600 FS @ 5 ml/kg seed with disease incidence of 28.77, 30.67, 31.78, 34.79, 37.62 and 63.32 per cent, respectively. The per cent disease incidence recorded in T11 (control) was 69.78 per cent.
At physiological maturity, the results revealed that ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l recorded lowest disease incidence of 24.78 per cent, followed by ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 30.5% SC @ 0.3 ml/l (27.65%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 70% WG @ 0.2 g/l (27.88%), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of afidopyrofen 5% DC @ 2 ml/l (28.28%). The next best treatments were ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of thiamethoxam 25% WG @ 0.2 g/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of fipronil 5% SC @ 1 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of flonicamid 50% WG @ 0.5 g/l, FS of imidacloprid 30.5% SC @ 0.3 ml/l), ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of dimethoate 30% EC @ 1.7 ml/l and ST with imidacloprid 600 FS @ 5 ml/kg seed with disease incidence of 30.15, 31.22, 33.57, 36.42, 39.57 and 65.32 per cent, respectively. The per cent disease incidence recorded in T11 (control) was 81.22 per cent.
Effect of different insecticides on the average disease incidence of YMD infecting blackgram
Out of the eleven treatments, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l recorded lowest disease incidence at different days after sowing with average disease incidence of 20.60 per cent and per cent reduction over control of 64.34 per cent. ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE @ 2 ml/l was comparable with ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 30.5% SC @ 0.3 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 70% WG @ 0.2 g/l and ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of afidopyrofen 5% DC @ 2 ml/l. The average incidence for ST + Foliar spray of Imidacloprid 30.5% SC, ST + FS of Imidacloprid 70% WG and ST + FS of Afidopyrofen 5% DC were 22.61, 23.03 and 24.13 per cent, respectively, with per cent reductions over control of 60.86, 60.14 and 58.24 per cent, respectively. Other treatments, including ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of thiamethoxam 25% WG @ 0.2 g/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of fipronil 5% SC @ 1 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of flonicamid 50% WG @ 0.5 g/l, FS of imidacloprid 30.5% SC @ 0.3 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of dimethoate 30% EC @ 1.7 ml/l and ST with imidacloprid 600 FS @ 5 ml/kg seed showed an average disease incidence of 25.61, 26.84, 27.92, 30.20, 32.44 and 48.21 per cent, respectively and
a per cent reduction over control was 55.68, 53.55, 51.68, 47.73, 43.86 and 16.57 per cent, respectively. The average disease incidence recorded in T11 (control) was 57.78 per cent (Table 3).
Effect of various insecticides on the yield of blackgram infected with YMD
The grain yield of blackgram crop infected with YMD was calculated per plot after harvesting and was converted into quintals per hectare. Maximum yield per hectare was recorded in ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l with seed yield of 7.87 q/ha with the highest B: C ratio of 2.53, followed by ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 30.5% SC @ 0.3 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of imidacloprid 70% WG @ 0.2 g/l and ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of afidopyrofen 5% DC @ 2 ml/l which recorded seed yield of 6.95 q/ha, 6.79 q/ha and 6.48 q/ha, respectively with the B: C ratio of 2.51, 2.46 and 1.86, respectively. The next best treatments were ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of thiamethoxam 25% WG @ 0.2 g/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of fipronil 5% SC @ 1 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of flonicamid 50% WG @ 0.5 g/l, FS of imidacloprid 30.5% SC @ 0.3 ml/l, ST with imidacloprid 600 FS @ 5 ml/kg seed + FS of dimethoate 30% EC @ 1.7 ml/l and ST with imidacloprid 600 FS @ 5 ml/kg seed) recorded seed yield of 5.60 q/ha, 5.41 q/ha, 5.28 q/ha, 5.04 q/ha, 4.45 q/ha and 4.30 q/ha, respectively with the B: C ratio of 2.13, 1.96, 1.69, 1.89, 1.63 and 1.70, respectively. The lowest yield per hectare was recorded in T11 (control) which recorded a seed yield of 3.36 q/ha with B: C ratio of 1.28 (Table 3 and 4).
The above investigations are in conformity with the findings of
Hugar et al., (2020), who conducted the field experiments at Agricultural Research Station, Dharwad during
kharif, 2016 and 2017 on the efficacy of a combi-product (diafenthiuron 30% + pyriproxyfen 8% SE) against whiteflies on cotton. The pooled data of two seasons as the impact of three sprays revealed 89.00 per cent reduction of whitefly in (diafenthiuron 30% + pyriproxyfen 8% SE) @ 1200ml/ha applied treatment. The results were also in agreement with
Bala (2023), who evaluated the bio-efficacy of the combined product (diafenthiuron 30% + pyriproxyfen 8% SE) against yellow mite and whitefly in chilli ecosystem. Results inferred that (diafenthiuron 30% + pyriproxyfen 8% SE) @1200 ml/ha was most effective in controlling yellow mite and whitefly in chilli.