Population Dynamics and Infestation Index of Cabbage Aphid, Brevicoryne brassicae [Homopetera: Aphididae] in Kashmir Valley

Population of B. brassicae was comparatively lower during Rabi 1999–2000 (5 to 175) as compared to Rabi 1998–99 (7 to 245) on all the four varieties of Cabbage tested. Two population peaks were recorded, one during October, (92 to 188) and (75 to 100) and another peak during June (99 to 245) and (126 to 175) coinciding with the head formation and sprouting stage of cabbage, during 1998–99 and 1999–2000, respectively on all the four varieties tested. However, maximum population was recorded on Uttam and minimum on Pride of India during the two cropping seasons of head and seed crops, respectively.