Bioefficacy and Persistent Toxicity of some Biopesticides and Insecticides against Cutworm, Agrotis ipsilon Hufner on Spring Potato

Field experiments were conducted during spring 2002–2003 to compare the bioefficacy and persistence toxicity/activity of biopesticides and organic manures with insecticides against cutworm, Agrotis ipsilon Hufner on potato. Studies revealed that the basal application gave significantly less incidence of A. ipsilon as compared to foliar treatments. Among basal application, chlorpyriphos (@ 400 g ai ha−1) proved highly effective in reducing tuber damage followed by organic manures Vikas (@ 450 kg ha−1) and Vipul (@ 450 kg ha−1) at both the locattons. Among foliar treatments, synthetic pyrethroids γ-cyhalothrin (@12.5 g ai ha−1) and cypermethrin (@ 75 g ai ha−1)) gave significantly better control than the rest of the foliar treatments. The biopesticides (microbial) B. thuringiensis (@ 3.96 x 107 IU ha−1), B. bassiana (@ 4.5 x 1012 cfu ha−1), neem derivative Achook t@ 3.38 g ai ha−1 azadirachtin) and B. bassiana in combination with cypermethrin were statistically superior over untreated check in suppressing A. ipsilon damage but were less effective than synthetic insecticides and organic manures. The persistence toxicity/activity studies indicated that cypermethrin had the highest persistent toxicity (1001.8, PT = 14 days) followed by γ-cyhalothrin (958.2), cypermethrin + B. bassiana (728.0), B. thuringiensis (696.9), B. bassiana (318.9) and Achook (250.8).