Vol. 11, Special Issue 7 (2022)

Author(s):
Rabindra Prasad, Nakkala Divakar Reddy, Ashish Narayan, T Alam, GS Giri and PP Singh

Abstract:
A study was conducted to know the field efficacy of botanical insecticides against sweet potato weevil. The experiment was laid during September, 2019 at research farm of Dholi, Bihar in randomized block design with 03 replications and 10 treatments. The sweet potato variety “Cross-4” is used as a susceptible test variety for sweet potato weevil. Experimental evidence has shown that the sweet potato weevil has a damage potential upto 50% in Bihar and 90% at National level. The sweet potato weevil is considered to be the single most destructive pest of sweet potato. Plants containing active insecticidal phytochemicals are gaining attention because of their broad spectrum insecticidal activity, safety, biodegradability and integrated crop management approaches as they are probable candidates for alternatives to chemical and synthetic insecticides. Treatments comprised of foliar application of botanical insecticides viz., Vine treatment with chlorpyriphos @ 1lit/ha, neem oil @ 2% aqueous, Yam bean seed extract @ 5% aqueous, Karanj oil (@ 2% aqueous, Tobacco decoction @5% aqueous and combination of vine treatment with chlorpyriphos 20 EC @ 1lit/ha along with application of Neem oil @ 2%, Yam bean seed extract @ 5%, Karanj oil @ 2% and Tobacco decoction @ 5% aqueous solution. Results indicated that minimum per cent of weevil infestation was recorded in vine treatment with chlorpyriphos 20 EC @1lit/ha along with spraying of neem oil @ 2%), followed by vine treatment with chlorpyriphos 20 EC @1lit/ha along with spraying of karanj oil @ 2% in terms of reducing vine infestation, tuber infestation and also offered protection to tubers in storage up to one month after harvesting, while the lowest efficacy and marketable tuber yield (t/ha) is recorded in treatment with chlorpyriphos 20 EC @ 1lit/ha., when applied alone. However, all the treatments were superior over untreated control. On the basis of benefit-cost ratio spraying of neem oil @ 2% having B:C ratio of 1:14.1 proved to be more economical as compared to other treatments.