Effect of Insecticides on Plant Characters and Yield of Rapeseed in Relation to Mustard Aphid, Liphaphis erysimi Kalt.

Reduction in mustard aphid, Lipaphis erysimi Kalt. population on rapeseed during 1988 season was possibly due to higher environmental temperature of 30° C compared to 21° C in the 1989 season. Crop maturity was also found to play a significant role on aphid populations. Number of aphids ranged from 70 to 96/shoot in plots treated with endosulfan and phosalone compared to 41 aphids in those treated with monocrotophos 15 days after treatment (DAT). Infested plants produced smaller pods, lesser number of pods/plant, fewer seeds/pod, lower 1000 seed weight, and lower germlnabillty compared to the healthy plants. First spray at flowering followed by second at 20 days interval controlled the aphids. Highest yield of rapeseed was recorded in plots treated with monocrotophos followed by those treated with phosalone, and endosulfan.