Management of Tobacco Stem Borer, Scrobipalpa heliopa in Virginia Tobacco

A field experiment was conducted for two seasons for management of tobacco stem borer, Scrobipalpa heliopa in Virginia tobacco, Nicotiana tabacum. Rynaxypyr 25 SC @ 0.0075% and flubendiamide 480 SC @ 0.012% were highly effective followed by spinosad 45 SC @ 0.018% in protecting tobacco from stem borer infestation when sprayed in the seed beds ten days before pulling the seedlings and ten days after transplanting (DAT) in the main field. The grade index was also found to be higher with net returns of ` 93,496, ` 91,862 and ` 86,135 and the B:C ratio was 2.09, 2.07 and 2.00, respectively in the plots treated with rynaxypyr, flubendiamide and spinosad. Studies on persistent toxicity of the promising insecticides against tobacco stem borer on tobacco showed that the persistent toxicity index (PTI) was highest (1405.26) for rynaxypyr followed by flubendiamide (1379.16) and spinosad (1302.08). The order of relative persistent toxicity was rynaxypyr > flubendiamide > spinosad > emamectin benzoate > chlorpyrifos.