EFFECTIVENESS OF NEEM OIL AND SOME INSECTICIDES IN MANAGING TOBACCO CATERPILLAR, SPODOPTERA LITURA (FAB.) ON CABBAGE

Abstract

An experiment was conducted at Sher-e-Bangla Agricultural University (SAU) farm during November to Februajy, 2007 to evaluate the effectiveness of neem oil and six insecticides for the management of tobacco caterpillar, Spodoptera lilura (Fab.). There were eight treatments comprising neem oil, Dursban 20EC, Marshal 20EC, Ripcord IOEC, Flubendiamide 24WG, Lebaycid 50EC, Actara 25W0 and untreated control. Cabbage variety 'LAURELS-F1 Hybrid' was used in this experiment. The experiment was laid out in Randomized Completely Block Design (RCBD) with 3 replications. Ripcord IOEC applied at seven days interval reduced 91.60, 86.48 and 86.68% infestation of leaf over control at early, middle and harvesting stage of head formation, respectively. Ripcord IOEC and Flubendiamide 24WG provided 89.98% reduction of tobacco caterpillar infestation over control. Neem oil also provided 70.01% reduction of tobacco caterpillar infestation of cabbage head by number over control. Both healthy and total yield were the highest in Ripcord IOEC (70.34 t/ha and 71.12 t/ha, respectively) treated plots. Similar healthy and infested yields were obtained (69.35 VIm and 70.1 It/ha, respectively) in Flubendiamide 24W0 treated plots. Ripcord 10EC and Flubendiamide 24WG provide more than 80% reduction of yield loss over control. Ripcord IOEC reduced 88.39% bores per infested leaves while Flubendiamide reduced 86.05% bores per infested leaf. Both Ripcord IOEC and Flubendiamide 24W0 reduced 92.38% larval population per infested head. There were highly negative correlations between percent leaf infestation and percent head infestation with yield of cabbage. The highest BCR (1.55) was obtained by the application of Ripcord IOEC at sveckly intervals and almost similar 8CR (1.49) was obtained by application of Flubendiamide 24WG.