EFFECTIVENESS OF SOME COMMONLY USED BOTANICALS IN MANAGING TOBACCO CATERPILLAR, SPODOPTERA LITURA (FAB.) ON CABBAGE

Abstract

The experiment was conducted in the field of Sher-e-Bangla Agricultural University farm, Sher-e-Bangla Nagar, Dhaka, Bangladesh during the period from November 2013 to February 2014 to study the effectiveness of commonly used botanicals in managing tobacco caterpillar, Spodoptera litura (Fab.) on cabbage. The experiment comprised six treatments and one untreated control. Six treatment were: T1: Neem oil @ 6 ml/L of water, T2: Neem oil @ 5 ml/L of water, T3: Neem oil @ 4 ml/L of water, T4: Mehgoni seed kernel @ 200 mg/L of water, T5: Neem leaf extract @ 200 mg/L of water, T6: Neem seed kernel extract @ 200 mg/L of water and an untreated control. Treatments were applied at 7 days intervals starting from the first initiation of the pest attack. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. It was revealed that the highest number of healthy head per plot (24.33) was recorded in T1, while the lowest number (18.67) was found in untreated control plot. The highest number of infested heads/plot (6.33) was recorded untreated control plot, while the lowest (0.67%) was found in T1 treatment. The highest percentage of infestation (33.90%) was attained in untreated control plot, whereas the lowest percentage (2.75%) was in T1 treatment. The highest percentage (91.88%) of cabbage head infestation reduction over control was found in T1, whereas the lowest value (49.25%) from T4 treatment. The lowest number of bores/leaf (1.33) was recorded in T1, while the highest number of bores (25.67) was recorded in untreated control plot. The lowest number of larvae/head (0.33) was recorded in T1, while the highest number (6.33) was found in untreated control plot. The maximum thickness of head (13.28 cm) was recorded in T1, while the minimum thickness (10.56 cm) was found in untreated control plot. The maximum diameter of head (11.34 cm), the highest gross yield per plant (2.02 kg), and The highest marketable yield per hectare (65.56 ton) was recorded in T1 treated plot, while the minimum diameter (9.34 cm), the lowest gross yield per plant (1.52 kg) and the highest marketable yield per hectare (65.56 ton) observed in untreated control plot. The highest benefit cost ratio (3.52) was estimated for T1 and the lowest (1.86) in T4 treatment. From the findings it is revealed that spraying of Neem oil @ 6 ml/L of water at 7 days interval (T1) was more effective among the commonly used botanical for reduction of cabbage plant infestation by tobacco caterpillar.