EFFECTIVENESS OF SOME INSECTICIDES FOR CONTROLLING ONION THRIPS (Thrips tabaci Lindeman) IN ONION

Abstract

The experiment was conducted at the Farm of Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, Bangladesh to study the effectiveness of some insecticides for controlling thrips during the period from November 2014 to March 2015. The experiment consists of the following management practices: T1: Actara 25 WG @ 0.2g/L of water ; T2: Nitro 505 EC @ 2ml/L of water; T3: Admire 200SL @ 0.5ml/L of water; T4: Neem Oil @ 4ml/L of water; T5: Malathion 57EC @ 2ml/L of water; T6: Tapnor 40 EC @ 2ml/L of water and T7: Untreated control. All the treatments were applied at 7 days intervals. The plants treated with T1 treated plot of onion (Actara 25 WG @ 0.2g/L of water), resulted significantly the lowest percentage of infested leaf compared to those of other treatments during vegetative stage, bulb formation stage and bulb filling stage. The tallest plant (41.26 cm) was recorded from T1 treatment (Actara 25 WG @ 0.2g/L of water), while the shortest plant was found from control (29.30 cm). Significantly the highest yield was obtained in plant under the treatment T1. The treatments T2 (Nitro 505 EC @ 2ml/L of water) and T3 (Admire 200SL @ 0.5ml/L of water) also gave more or less similar result as treatment T1. The yield contributing characters have found the highest in T1 treatment for girth of bulb, weight of individual bulb and yield per hectare. The highest benefit cost ratio (4.64) was also found in T1 may be due to the minimum infestation and cost compared to the other treatments.