EFFECTIVENESS OF SOME BOTANICALS IN CONTROLLING MAJOR LEPIDOPTERAN INSECT PESTS OF SUMMER CABBAGE

Abstract

An experiment was conducted in the experimental field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the period from May, 2018 to September, 2018 to evaluate some botanicals applied against major insect pests of summer cabbage. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications .Seven treatments, viz., T 1 (Mahogany seed kernel extract @ 3.0 ml/L of water at 7 days interval); T 2 (Tobacco leaf extract @ 3.0 ml/L of water at 7 days interval); T 3 (Garlic extract @ 3.0 ml/L of water at 7 days interval); T 4 (Neem leaf extract @ 3.0 ml/L of water at 7 days interval); T 5 (Neem seed kernel extract @ 3.0 ml/L of water at 7 days interval); T 6

(Neem oil @ 3.0 ml/L of water at 7 days interval) and T 7 (untreated control) were used. Among the management practices, the lowest mean infestation of cabbage leaf by semi-looper (4.79 leaves/5 plants), tobacco caterpillar (6.25 leaves/5 plants) and diamond back moth larvae 4.39 leaves/5 plants) was found in T 6 that reduced highest leaf infestation over control (59.40%, 61.73% and 68.03% respectively); whereas the highest infestation by semi-looper (11.80 leaves/5 plants), tobacco caterpillar (16.33 leaves/5 plants) and diamond back moth larvae (13.73 leaves/5 plants) was found in T 7. The lowest mean incidence of semi-looper (5.47 larvae/5 plants), tobacco caterpillar (9.17 larvae/5 plants) and diamondback moth (3.30 larvae/5 plants) was found in T 6 that reduced highest incidence over control (65.09%, 49.97% and 66.57% respectively); whereas the highest values of all these parameters were recorded from untreated control treatment (T 7 ).The lowest cabbage head infestation(13.00%) was recorded in T 6 , that gave the highest yield of cabbage (36.50 tha -1 ) followed by T 4 (31.83 tha -1 ). From the study it was found that there is a strong negative relationship between leaf infestation intensity and single head weight and between leaf infestation intensity and yield (tha ) of cabbage. Moreover, a strong negative relationship was observed between percent head infestation and weight of individual head at harvest.