Efficacy of seed treatment and foliar application of against soybean stem fly Melanagromyza sojae

A field experiment on the effectiveness of seed treatment and foliar application of insecticides against soybean stem fly Melanagromyza sojae (Zehntner) was carried out at the All India Coordinated Research Project (AICRP) on Soybean, Gandhi Krishi Vignan Kendra (GKVK), Bengaluru, Karnataka during kharif 2017. The seeds treated with thiamethoxam 30FS @ 10 ml/kg seed and foliar application of thiamethoxam 25WG 0.40 g/l at 30 days after germination (DAG) were found effective. It was on par with seeds treated with imidacloprid 48FS @ 1.25 ml/kg seed and foliar application of imidacloprid 17.8SL @ 0.50 ml/l at 30 DAG. The plots treated with these gave higher grain yield of 1794.48 and 1678.89 kg/ha, respectively. Higher net gain of 1: 4.22 was obtained from the seeds treated with thiamethaxom 30FS @ 10 ml/kg seed and foliar application of thiamethoxam 25WG 0.40 g/l at 30 DAG; and it proved to be highly cost effective. The foliar application of chlorantraniliprole 18.5SC @ 0.30 ml/l at 10 and 30 DAG was equally effective compared to thiamethoxam and recorded the C: B ratio of 1: 3.94. The plots treated with quinalphos 25EC @ 2 ml/l at 10 and 30 DAG led to the least stem tunneling of (26.73%) and the low grain yield of 1177.78 kg/ha.