Evaluation of petroleum spray oil against turnip aphid, Lipaphis erysimi (Kaltenbach) infesting oilseed brassica

Petroleum spray oil was evaluated against turnip aphid, Lipaphis erysimi (Kaltenbach) on Brassica juncea cv. PBR 210 at Punjab Agricultural University, Ludhiana during 2009–10 and 2010–11 crop seasons. Different treatments of petroleum spray oil included: 0.50, 0.75, 1.00, 1.25, 1.50 and 1.75% along with dimethoate 30 EC @ 1 lt ha−1 and untreated control. All the treatments resulted in significant reduction in the aphid population after 3 days of spray except petroleum spray oil (0.5%) and remained effective for up-to 10 days. Though, the chemical insecticide dimethoate was the most effective, petroleum spray oil @ 1.75% was statistically at par with it with 82.2–86.9% reduction in the aphid population and consistently remained effective for up to 10 days after application. Further, petroleum spray oil at either of the concentrations did not result in any toxic effect on Coccinella septempunctata and honey bees. The seed yield in the case of petroleum spray oil at all the concentrations, except at 0.5%, was statistically at par with the chemical insecticide dimethoate (1 lt ha−1) in 2009–10, however, in 2010–11, the yield differences were non-significant due to low aphid population. Keeping in view its efficacy, petroleum spray oil has the potential to be used as an alternative to chemical insecticides for the management of turnip aphid.