Efficacy of various insecticidal spray schedules against insect pests of soybean

Abstract

Two sprays were given in the soybean, of which first spray was given against whiteflies, semilooper and girdle beetle at 35 days after germination (DAG) and second spray was given at 55 DAG against gram pod borer and tobacco caterpillar. The significant maximum reduction in white fly population was recorded in case of thiamethoxam 25 WG at 3 and 5 days after spray (DAS) during the years 2012 and 2013, respectively. It was followed by imidacloprid 200 SL, while the significant highest reduction in the larval population of semilooper and girdle beetle was recorded in case of profenophos 50 EC at 3 and 5 (DAS) during the years 2012 and 2013, respectively. It was followed by triazophos 40 EC and dimethoate 30 EC against semilooper and girdle beetle, respectively. In the second spray, indoxacarb 14.5 EC @ 345 ml/ha caused significantly maximum reduction of gram pod borer and tobacco caterpillar larvae at 3 and 5 DAS during the years 2012 and 2013, respectively. Similar trends were also observed at 7 DAS during both the years. The insecticidal spray schedule comprising first spray of triazophos 40 EC @ 1.25 l/ha at 35 DAG followed by second spray of flubendiamide 480 SC @ 100 ml/ha at 55 DAG provided the highest mean seed yield of 1925 kg/ha. The maximum net profit of Rs. 15, 008/ha was obtained in case of spray schedule comprising first spray of triazophos 40 EC @ 1.25 l/ha at 35 DAG followed by second spray of flubendiamide 480 SC @ 100 g/ha at 55 DAG with the maximum cost: benefit ratio of 1: 8.52. The minimum net profit of Rs. 3, 698/ha was obtained in first spray of monocrotophos 36 SL followed by second spray of triazophos 40 EC with the minimum cost: benefit ratio of 1: 3.32.