ECO-FRIENDLY MANAGEMENT OF MAJOR INSECT PESTS OF CABBAGE

Abstract

An experiment was conducted in the experimental field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the period from October, 2014 to March, 2015 to evaluate some management practices applied against major insect pestsof cabbage. The experiment was laid out in Randomized Complete Block Design replicated with three times. The management practices were six botanicals, two synthetic insecticides and one untreated control. Those were T1 (spraying of Neem leaf extract @ 3.0 ml/L of water at 7 days interval); T2 (Neem seed kernel extract @ 3.0 ml/L of water at 7 days interval); T3 (Neem oil @ 3.0 ml/L of water at 7 days interval); T4 (Garlic extract @ 3.0 ml/L of water at 7 days interval); T5 (Thuza leaf extract @ 3.0 ml/L of water at 7 days interval); T6 (Sevin 85 WP @ 2.0 g/L of water at 7 days interval); T7 (Admire 200 SL @ 1.0 ml/L of water at 7 days interval); T8 (Phytoclean @ 3.0 ml/L of water at 7 days interval) and T9 (untreated control). Among the management practices, the lowest mean infestation of cabbage leaf by semi-looper (2.0 leaves/5 plants), cabbage caterpillar (1.95 leaves/5 plants) and diamond back moth larvae (1.5 leaves/5 plants) was found in T7 that reduce highest leaf infestation over control (85.72%, 86.02% and 89.66%, respectively); whereas the highest infestation by semi-looper (14.01 leaves/5 plants), cabbage caterpillar (13.93 leaves/5 plants) and diamond back moth larvae (14.21 leaves/5 plants) was found in T9. Among the botanicals the lowest infestation of cabbage leaf by semilooper (3.76 leaves/5 plants), cabbage caterpillar (3.33 leaves/5 plants) and diamond back moth (2.12 leaves/5 plants) was found in T3. No cutworm infestation (0.0) was recorded at 3 days after transplanting (DAT) of cabbage seedlings and the cutworm infestation was initiated at 5 DAT. The maximum infestation (2.0 to 3.0 infested seedlings/plot) was recorded at 7 DAT, and then infestation declined gradually with the increase of time. But no infestation was recorded at 13 DAT. The lowest cabbage head infestation was recorded (6.08%) in T7, that gave the highest yield of cabbage (19.96 t/ha) followed by T3 (19.71 t/ha). The cutworm infestation on cabbage seedlings was ranged from 47.62 to 57.14% in the field, where the highest infestation was recorded in T5, which statistically similar with all other treatments. On the contrary, the lowest cutworm infestation (47.62%) was recorded in T2 and T6. Therefore, that management practice particularly for cutworm should be applied between 3 to 13 DAT of cabbage seedlings in the field. Considering the number of beneficial arthropods, the highest mean incidence of ants (4.53 ants/plot/inspection) was recorded in T3 but the lowest in T7 (1.73 ants/plot/inspection). The highest incidence of spiders was recorded in T9 (4.53 spiders/plot/inspection) and the lowest in T7 (1.47 spiders/plot/inspection). The highest incidence of lady bird beetles (4.75 beetles/plot/inspection) was recorded in T3 and the lowest in T7 (1.00 beetles/plot/inspection); i.e. the highest reduction of infestation was achieved by the application of Admire 200 SL treatment (T7), but it also reduced highest level beneficial arthropod population than botanical based treatments.