Population dynamics of cotton bollworms and management of Earias spp. on Gossypium arboreum L.
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Date
2023-01
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Chaudhary Charan Singh Haryana Agricultural University hisar
Abstract
Field experiments on population dynamics of cotton bollworms and management of Earias spp. on Gossypium arboreum L. were conducted at CCS Haryana Agricultural University, Hisar (Haryana) during kharif, 2020. Data on trap catches indicated that first peak activity of Earias spp., Helicoverpa armigera and Pectinophora gossypiella was recorded in 29th Standard Meteorological Week (SMW) whereas highest peak of all bollworms was found in 41st SMW. Square damage (8.47%) and green boll damage (30.43%) were recorded maximum in 30th and 43rd SMWs, respectively. Weather parameters also affected the population and infestation of bollworm complex. Adult catches of P. gossypiella showed a significant negative correlation with minimum temperature and a highly significant negative correlation with relative humidity (evening). Minimum temperature and relative humidity (evening) showed a highly significant negative correlation with green boll infestation. Also, morning relative humidity had a significant negative correlation with green boll damage. Out of 20 genotypes of desi cotton, the minimum mean square damage due to Earias spp. was recorded on genotype FDK 124 (0.75%) followed by HD 541 (0.79%) and HD 558 (0.92%) whereas minimum mean boll damage due to Earias spp. was recorded on genotype HD 550 (5.56%) followed by AAH-1 (6.22%) and HD 535 (6.63%). Maximum yield (27.98 q/ha) was recorded in genotype HD 550 and HD 535 followed by 27.57 q/ha in HD 541 and AAH-1 and 27.16 q/ha in HD 545. All the insecticides were found significantly superior to untreated control in suppressing the incidence of Earias spp. Combination product of chlorantraniliprole 9.30% + lambda-cyhalothrin 4.60% ZC @ 250 ml ha-1 was found most effective against Earias spp. with lowest larval population (5.00 and 2.89 larvae/50 green bolls) and green boll damage (8.00 and 4.44%) after first and second spray, respectively. It was followed by spinosad 45.00% SC @ 220 ml ha-1 (5.33 & 3.56 larvae/50 green bolls; 8.44 & 5.11% green boll damage) and chlorantraniliprole 18.50% SC @ 150 ml ha-1 (5.67 & 3.44 larvae/50 green bolls; 8.44 & 5.11% green boll damage) after first and second spray, respectively. All the insecticides suppressed the natural enemy population at 3 days after both sprays over untreated control however, non-significant differences were observed after 7 days of first and 14 days of each spray. Among insecticides, spinosad 45.00% SC @ 220 ml/ha treated plots had maximum natural enemy population of 1.24 and 1.09 natural enemies/plant after first and second spray, respectively. Also, spinosad 45.00% SC resulted in maximum incremental yield (7.09 q/ha) followed by chlorantraniliprole 9.30% + lambda-cyhalothrin 4.60% ZC (6.63 q/ha), chlorantraniliprole 18.50% SC (6.51 q/ha) and flubendiamide 39.35% SC (6.06 q/ha). However, maximum Incremental Cost Benefit Ratio (ICBR) was obtained with emamectin benzoate 5% SG @ 220 g/ha (1: 6.12) followed by chlorantraniliprole 9.30% + lambda-cyhalothrin 4.60% ZC (1:4.99), chlorantraniliprole 18.50% SC (1:4.35) and indoxacarb 14.5% SC @ 500 ml/ha (1:3.35).