Plant damage level one day before insecticide application
It was observed that Holotrichia sp., Anomala benghalensis, Heteronychus sp. Anomala dimidiata, and Adoretus simplex were the major species of white grub. In the present study, there were 9 insecticidal treatments which were applied in September and the data on plant damage was recorded at 40th, 60th and 80th days after insecticides application. The result revealed that the percent plant damage level of soybean due to white grubs on the day before application ranged from 13.13–17.17 and 17.17–19.70 during 2019 and 2020, respectively. No significant difference was found among different plots at one day before application (Tables 2 & 3).
Table 2
Efficacy of various insecticides were evaluated against white grubs infesting soybean variety PS-1225 during, 2019
Name of insecticides | Dose a.i./ha | Cumulative percent plant damage | Average cumulative plant damage (%) | Reduction over control (%) | Grain yield (q/ha) | Cost: Benefit ratio |
1 DBA | 40 DAA | 60DAA | 80 DAA |
Carbofuran 3G | 750 | 15.15 (23.30) | 8.59 (17.02)f | 10.10 (18.52)f | 11.62 (19.92)f | 10.10 | 54.89 | 16.78 (4.21) | 1:4.53 |
Clothianidin 50 WDG | 120 | 17.17 (24.48) | 3.03(9.80)ab | 5.05(12.96)ab | 6.06 (14.25)ab | 4.71 | 78.95 | 20.56 (4.64) | 1:5.19 |
Fipronil 0.3G | 50 | 16.16 (25.19) | 6.06 (14.18)cde | 8.08 (16.45)cde | 9.09 (17.55)cde | 7.74 | 65.41 | 17.04 (4.25) | 1:6.44 |
Thiamethoxam 25 WG | 80 | 15.66 (24.85) | 10.61 (18.98)g | 11.62 19.92)g | 13.13(21.24)g | 11.78 | 47.37 | 15.56 (4.07) | 1:6.50 |
Imidacloprid 70 WG | 300 | 13.64 (25.23) | 5.56 (13.60)cd | 7.58 (15.93)cd | 8.59 (17.02)cd | 7.24 | 67.67 | 19.44 (4.52) | 1:3.92 |
Chlorantraniliprole 0.4 GR | 100 | 13.13 (25.94) | 5.05 (12.84)c | 7.07 (15.40)c | 8.08 (16.50)c | 6.73 | 69.92 | 19.81 (4.56) | 1:3.24 |
Fipronil 40 + Imidacloprid 40WG | 300 | 14.14 (24.83) | 2.53 (9.04)a | 4.04 (11.55)a | 5.56 (13.60)a | 4.04 | 81.95 | 23.33 (4.93) | 1:6.86 |
Chlorpyrifos 10G | 300 | 13.64 (25.61) | 12.12 (20.35)h | 13.64 (21.65)h | 15.15 (22.89)h | 13.64 | 39.10 | 13.89 (3.85) | 1:4.67 |
Emamectin benzoate 5SG | 12.5 | 14.65 (24.48) | 14.14 (22.06)i | 15.66 (23.30)i | 17.17 (24.46)i | 15.66 | 30.07 | 13.33 (3.78) | 1:2.14 |
Control | - | 15.15 (23.30) | 20.20 (26.71)j | 23.23(28.81)j | 26.26 (30.83)j | 23.23 | - | 10.56 (3.38) | - |
CD (P = 0.05) | - | NS | 1.46 | 1.51 | 1.44 | - | - | 0.32 | - |
SEM (±) | - | | 0.49 | 0.51 | 0.49 | - | - | 0.11 | - |
CV | - | | 5.16 | 4.78 | 4.24 | - | - | - | - |
DBA-Day Before Application; DAA-Day after application; NS-Non-significant |
Means followed by the same alphabets in columns did not differ significantly [p = 0.05] by Post Hoc Tukey’s HSD |
Labour charge @ Rs. 300/day; Assessed soybean price: @ Rs. 3600.00/q |
Table 3
Efficacy of various insecticides were evaluated against white grubs infesting soybean variety PS-1225 during, 2020
Treatments | Dose a.i./ha | Cumulative percent plant damage | Average cumulative plant damage (%) | Reduction over control (%) | Grain yield (q/ha) | Cost: Benefit Ratio |
1 DBA | 40 DAA | 60 DAA | 80 DAA |
Carbofuran 3G | 750 | 17.68 (24.86) | 8.08 (16.50)f | 10.10 (18.52)f | 11.11 (19.46)f | 9.76 | 58.63 | 17.59(4.31) | 1:4.10 |
Clothianidin 50 WDG | 120 | 18.69 (25.61) | 4.04 (11.43)ab | 5.56 (13.60)ab | 7.07 (15.35)ab | 5.56 | 76.46 | 21.30(4.72) | 1:4.85 |
Fipronil 0.3G | 50 | 19.70 (26.30) | 6.57 (14.83)cde | 8.59 (17.02)cde | 9.60 (18.03)cde | 8.25 | 65.05 | 18.52(4.42) | 1:6.66 |
Thiamethoxam 25 WG | 80 | 19.19 (25.98) | 9.60 (18.03)f | 11.62 (19.89)g | 12.63 (20.81)g | 11.28 | 52.21 | 16.48(4.18) | 1:5.95 |
Imidacloprid 70 WG | 300 | 18.69 (25.59) | 6.06 (14.18)cd | 8.08 (16.50)cd | 9.09 (17.51)cd | 7.74 | 67.19 | 19.63(4.54) | 1:3.31 |
Chlorantraniliprole 0.4 GR | 100 | 17.68 (24.83) | 5.56 (13.53)c | 7.58 (15.93)c | 8.59 (17.02)c | 7.24 | 69.33 | 20.37(4.62) | 1:2.91 |
Fipronil 40 + Imidacloprid 40WG | 300 | 19.19 (25.96) | 3.54 (10.79)a | 5.05 (12.96)a | 6.06 (14.25)a | 4.88 | 79.31 | 24.44(5.04) | 1:6.75 |
Chlorpyrifos 10G | 300 | 19.70 (26.35) | 11.11 (19.46)h | 13.13 (21.24)h | 14.14 (22.08)h | 12.79 | 45.79 | 15.37(4.04) | 1:4.99 |
Emamectin benzoate 5SG | 12.5 | 17.68 (24.86) | 12.63 (20.78)i | 14.65 (22.48)i | 15.66 (23.30)i | 14.31 | 39.37 | 15.19(4.02) | 1:2.79 |
Control | - | 17.17 (24.48) | 19.19 (25.34)j | 23.23 (28.81)j | 26.77 (31.15)j | 23.06 | - | 11.85(3.58) | - |
CD (P = 0.05) | - | NS | 1.40 | 1.23 | 1.28 | - | - | 0.28 | - |
SEM (±) | - | | 0.47 | 0.41 | 0.43 | - | - | 0.09 | - |
CV | - | | 4.92 | 3.83 | 3.76 | - | - | - | - |
DBA-day before application; DAA-day after application; NS-Non-significant |
Means followed by the same alphabets in columns did not differ significantly [p = 0.05] by Post Hoc Tukey’s HSD |
Labour charge @ Rs. 300/day; Assessed soybean price: @ Rs. 3600.00/q |
Plant damage level on 40th day after application
The statistical analysis of mean data recorded after forty days after application of insecticidal treatment revealed that all the treatments were found significantly superior in reducing the infestation of sugarcane as compared to untreated control. The white grub damage ranged from 2.53–20.20% and 3.54–19.19% during 2019 and 2020, respectively. The lowest plant damage of 3.03% and 4.04% was recorded from the plot treated with Fipronil 40% + Imidacloprid 40% WG, followed by Clothianidin 50 WDG (3.03% and 4.04% plant damage) during 2019 and 2020, respectively. The treatment of Clothianidin 50 WDG was statistically at par with the best treatment, i.e., Fipronil 40% + Imidacloprid 40% WG. In the next in order effective treatments were Chlorantraniliprole 0.4GR, Fipronil 0.3G and Imidacloprid 70WG with during both the year consecutively. However, these treatments were also statistically at par with each other and significantly superior over control during the 2019 and 2020, respectively. Next in order of plant damage level, it was recorded that Carbofuran 3G followed by Thiamethoxam 25WG and Chlorpyrifos 10G were found moderately effective treatments during both years, consecutively. Emamectin benzoate 5SG @12.5g a.i./ha treated plot was found least effective with 14.14 and 12.63% plant damage but significantly superior over control and maximum plant damage of 20.20 and 19.19% was noticed from untreated plot during the year 2019 and 2020, respectively (Tables 2 & 3).
Plant damage level on 60th day after application
At the 60th days after insecticide application, all the treatments maintained their efficacy and significance in comparison to the control. The plot treated with Fipronil 40% + Imidacloprid 40% WG provided the best result and recorded lowest cumulative plant damage of 4.04 and 5.05% followed by Clothianidin 50WDG with 5.05 and 5.56% of plant damage during both consecutive years of study. Chlorantraniliprole 0.4GR @ 100g a.i./ha was found next effective treatment with 7.07 and 7.58% cumulative plant damage followed by Imidacloprid 70WG (7.58 and 8.08) and Fipronil 0.3G (8.08 and 8.59%) was found to be moderately effective and these treatments were found at par with each other during year 2019 and 2020, respectively. The plot treated with Emamectin benzoate 5SG was found maximum cumulative plant damage level with 15.66 and 15.15% followed by Chlorpyrifos 10G, Thiamethoxam 25WG and Carbofuran 3G during two consecutive year of study and these all treatments were found significantly superior over control. The highest cumulative plant damage i.e., 23.23% and 23.74 was recorded in control plot during the year 2019 and 2020 cropping season, respectively (Tables 2 & 3).
Plant damage level on 80th day after application
Data recorded on 80th day after application indicates that the minimum cumulative plant damage 5.56 and 6.06% was recorded in the plot treated with Fipronil 40% + Imidacloprid 40% WG @300g a.i./ha and it was found best among all the treatments followed by next effective treatment was Clothianidin 50WDG @120g a.i./ha (6.06 and 7.07%) and Chlorantraniliprole 0.4GR @ 100g a.i./ha (8.08 and 8.59%) and the treatment Clothianidin 50WDG @ 120g a.i./ha was statistically at par with best treatment i.e. Fipronil 40% + Imidacloprid 40% WG @300g a.i./ha but significantly superior from rest of treatment during the year 2019 and 2020, respectively. Next in order the cumulative plant damage 8.59 and 9.09% was recorded in the plot treated with Imidacloprid 70WG followed by Fipronil 0.3G and Carbofuran 3G during both consecutive year of study. Next succeeding treatments which were also effective over the control i.e., Thiamethoxam 25WG @80g a.i./ha recorded 13.13 and 12.63% cumulative plant damage followed by Chlorpyrifos 10G (15.15 and 14.14%) and Emamectin benzoate 5SG (17.17 and 15.66%) during both the year. The highest cumulative plant damage was recorded from untreated control (26.26 and 26.77%) during the year 2019 and 2020, respectively (Tables 2 & 3).
Percent reduction over control
The result revealed that Fipronil 40% + Imidacloprid 40% WG @300g a.i./ha had the maximum plant damage reduction over control of 81.95 and 80.58% and found to be the best treatment followed by Clothianidin 50WDG @120g a.i./ha (78.95 and 77.68%), Chlorantraniliprole 0.4GR @100g a.i./ha (69.92 and 70.43%) during both the years of study. Next in order, the treatment was found moderately effective and recorded 67.67 and 68.26% reduction with the treatment of Imidacloprid 70WG @ 300g a.i./ha followed by Fipronil 0.3G @ 50g a.i./ha (65.41 and 66.08%) and Carbofuran 3G @ 750g a.i./ha (54.89 and 58.83%) during both the year consecutively. The lowest reduction over control was recorded in the treatment of Emamectin benzoate 5SG @ 12.5g a.i./ha (30.07 and 39.27%) followed by Chlorpyrifos 10G @ 300g a.i./ha (39.10 and 45.78%) and Thiamethoxam 25WG @ 80g a.i./ha (47.37 and 52.31%) during the year 2019 and 2020, respectively and these treatments was found significantly superior over control (Table 2 & 3).
Yield assessment
All insecticidal treatments increased soybean yield compared to control during the 2019 and 2020 cropping seasons. Fipronil 40% + Imidacloprid 40% WG @ 300g a.i./ha produced the highest yield of 23.33 and 24.44 q/ha during two years of study and it was found significantly superior over the rest of the treatments (Table 2 & 3).
Clothianidin 50WDG @120g a.i./ha was second most effective treatment which recorded with the yield of 20.56 and 21.30 q/ha followed by Chlorantraniliprole 0.4 GR @ 100g a.i./ha (19.81 and 20.37 q/ha), Imidacloprid 70 WG @ 300g a.i./ha (19.44 and 19.63 q/ha) during both year of study. Next in order, yield recorded in plot treated with Fipronil 0.3G @ 50G a.i./ha with 17.04 and 18.52 q/ha followed by Carbofuran 3G @ 750g a.i./ha 16.78 and 17.59 q/ha during both consecutive years of study. The lowest yield was recorded in the treatment of Emamectin benzoate 5SG @ 12.5g a.i./ha with 13.33 and 15.19 q/ha followed by Chlorpyrifos 10G @ 300g a.i./ha (13.89 and 15.37 q/ha) and Thiamethoxam 25WG @ 80g a.i./ha (15.56 and 16.48) during both years of study consecutively. Minimum yield of 10.56 and 11.58 q/ha was recorded with the untreated control during 2019 and 2020, respectively (Table 2 & 3).
The cost benefit ratio of different treatments has been calculated for 2019 and 2020 and presented in the Table 4 and 5 respectively. Based on the field trials, the highest Cost: Benefit ratio (1:6.86 and 1:6.75) was found in Fipronil 40% + Imidacloprid 40% WG @ applied 300g a.i./ha treatment and the lowest Cost: Benefit ratio was recorded in the plot treated with Emamectin benzoate 5SG @ 12.5g a.i./ha with 1:2.14 and 1:2.79 during in the year of 2019 and 2020, respectively (Table 2 & 3).