Bio-efficacy of synthetic insecticides against onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae)
SH Shweta, N Gangadhar, JB Gopali, MP Basavarajappa and HP Hadimani
The experiment was conducted under field condition at Haveli Farm, University of Horticultural sciences, Bagalkot to evaluate the efficacy of synthetic insecticides against onion thrips during kharif season (2017 - 18). The experiment plot area was replicated thrice and eight treatments with randomised block design. The results revealed that thiamethoxam 25 WG @ 25 g a.i./ha recorded significantly lowest population of thrips after first, second and third spray during the experimental period by recording 4.90 thrips per plant which was at par with imidacloprid 17.8 SL @ 22.25 g a.i./ha with 5.19 thrips per plant indicating the superiority of both the treatments against onion thrips. The next best treatments were, cyazypyr10.26 OD @ 76.95 g a.i./ha, diafenthiuron 50 WP @ 250 g a.i./ha and tolfenpyrad 15 EC @ 150 g a.i./ha with 6.89, 7.29 and 7.56 thrips per plant, respectively. Whereas, lamda cyhalothrin 5 EC @ 12.5 g a.i./ha and chlorfenapyr 10 SC @ 12.5 g a.i./ ha found to be least effective in reducing thrips population with 8.67 and 8.46 thrips/plant. The data on bulb yield indicated that highest bulb yield was registered in thiamethoxam 25 WG @ 25 g a.i./ha and imidacloprid 17.8 SL @ 22.25 g a.i./ha treated plots with 25.39 and 24.67 t per hectare, respectively. Whereas, minimum bulb yield was noticed with lambda cyhalothrin 5 EC @ 12.50 g a.i./ha treated plots (17.94 t/ha).