Vol. 11, Special Issue 5 (2022)

Author(s):
Rajavel DS, B Usha Rani and P Logeshkumar

Abstract:
Field experiments were conducted in two locations to evaluate the efficacy of certain insecticides against Onion Thrips (Thrips tabaci). Imidacloprid, Fipronil, Spinosad, Chlorfenapyr, Profenofos, dimethoate (Standard Check) and untreated check were the seven treatments. Two rounds of treatment sprays were given at fortnight intervals and pre and post treatment counts were recorded on 3, 7 and 14 Days after treatment (DAT). Natural enemy (spider) population and yield data were also recorded. In the first experiment, Spinosad @ 1ml/lit recorded mean thrips population of 3.19/ plant followed by Imidacloprid @ 1 ml/ lit (4.97/ plant). The standard check recorded 9.67 thrips per plant and in untreated check the mean population was 31.33. In the second experiment also the same trend was observed. Spinosad @ 1ml/lit was the best treatment (2.56 thrips/ plant) followed by imidacloprid (3.31 thrips / plant). Both the treatments were on par. Highest population of 22.0 thrips / plant was recorded in untreated check. The impact of newer insecticides on spider population in field condition revealed that Spinosad and Imidacloprid treatments recorded higher spider population (7.17 and 6.50 in I experiment, 9.17 and 8.50 in II experiment). The lowest spider population was recorded in standard check dimethoate 2.0 ml/ lit. Highest yields (18.1 t/ha, 18.4 t/ ha) and higher benefit cost ratio (2.94, 2.98) were obtained in spinosed treatment and this was followed by imidacloprid@ 1 ml/ lit.