Evaluation of different insecticides against mustard aphid, Lipaphis erysimi Kalt. on mustard crop

Field studies were conducted to determine the efficacy of different insecticides against mustard aphid, Lipaphis erysimi Kalt. on mustard crop at the Oilseed Section Agricultural Research Institute, Tandojam. The seeds of Toria Selection variety were sown in a completely randomized block design with four replicates. Each replicate comprised of six sub-plots for respective insecticide including control. Each sub- plot had 8 lines of Toria plants of 6 meters length spaced at 30 cm. The recommended doses of Thiodan 35EC, Sumicidin 20EC, Nuvacron 40SCW, Dimecron 100EC and Advantage 20EC were sprayed twice at fortnight intervals. First spray was applied 40 days after germination of Toria- plants. The solutions of the insecticides were sprayed on v/v basis in water and sprayed with the help of hand operated knapsack sprayer. The first 6 lines of plants in the sub-plots for respective insecticides were sprayed where as one line on each side was kept as buffer. The pre-treatment observation on counts of mustard aphid was recorded 1, 2, 3, 7, 14 days of each spray. The help of Henderson and Tilton formula calculated the reduction percentages and the percentages in the population of mustard Aphis was calculated. The data thus obtained was subjected to statistical analysis. The results on the reduction percentage in the population of mustard aphis after different time intervals of each spray showed that all the insecticides under trail had higher initial killing effect on the pest. Although the toxicity and effectiveness of all insecticides decreased as the time after spray elapsed. Among all the insecticides Dimecron 100EC and Thiodan 35EC were comparatively more effective and persistent than rest of the insecticides such as Nuvacron 40SCW, Advantage 20EC and Sumicidin 20EC in both sprays. It could be inferred that Dimecron 100EC and Thiodan 35EC can be effectively sprayed on mustard to control of mustard aphid when in epidemic.