EVALUATION OF SOME INSECTICIDES AGAINST OKRA SHOOT AND FRUIT BORER EARIAS VITTELLAFAB.

Abstract

The study was conducted in the experimental field of Sher-e-Bangla Agricultural University, Dhaka during the period from April to August, 2011 to evaluate of some promising chemical insecticides applied against okra shoot and fruit borer (Earias vittella Fab.). The treatments of the experiment were composed of five promising insecticides along with one botanical insecticide and one untreated control viz. T1 = Neem oil @ 4 ml/L of water sprayed at 7 days interval, T2= Caught 10 EC @ 1ml/L of water sprayed at 7 days interval, T3 = Suntap 50 SP @ 1.2g/L of water sprayed at 7 days interval, T4 = Marshal 20 EC@ 2ml/L of water sprayed at 7 days interval, T5 = Dursban 20 EC @ 1ml/L of water sprayed at 7 days interval, T6 = Diazinon 60 EC@ 1ml/Lof water sprayed at 7 days interval, T7= Untreated control. The experiment was laid out in Randomized Complete Block Design (RCBD) with four replications. The data were recorded on shoot infestation at vegetative and fruiting stages; fruit infestation at early, mid and late fruiting stage; plant and yield related attributes as well as yield of okra. Among six treatments, Diazinon 60EC reduced the highest percent of shoot infestation (79% & 86.29%) over control at vegetative and fruiting stage, respectively followed by neem oil (79.68% & 78.06%, respectively), whereas Marshal 20 EC showed the least performance (63.85% & 63.85%, respectively). In case of fruit infestation, Diazinon 60EC reduced the highest percent of fruit infestation by number (84.48%, 86.27% & 89.06%) and weight (79.91%, 82.09% & 83.58%) over control at early, mid and late fruiting stages, respectively followed by neem oil and than other treatments, whereas Marshal 20 EC showed the least performance. Considering plant and yield related attributes, Diazinon 60EC increased the highest percent of plant height (53.35%), number of branch per plant (64.70%), fruit length (43.28%) and girth (9.76%), number of fruit per plant (46.42%) and single fruit weight (41.64%) over control followed by neem oil, Caught 10 EC, Suntap 50 SP, Dursban 20 EC and Marshal 20 EC, where Marshal 20 EC showed the least performance. Similarly, the highest fruit yield (15.44 ton/ha) was also achieved by Diazinon 60 EC with the increase of 14.88% yield over control than neem oil and other insecticides, whereas Marshal 20 EC showed the least performance (13.53 ton/ha) with the lowest percent of yield increase (0.67%). The yield of okra was negative correlated with shoot (r = 0.3813) and fruit (r = 0.3895) infestation, but positively correlated with the yield attributes such as number of branch per plant (r = 0.9192) and length of fruits (r = 0.7612). Considering the economic returns, Diazinon 60EC gave the highest benefit cost ratio (6.90) than Dursban 20EC (5.80), neem oil (4.30) and others, where the lowest BCR (1.28) was achieved by Marshal 20EC. Though neem oil gave third highest BCR (4.30), but produced second highest yield (14.44 ton/ha). Thus neem oil was considered as an economically viable as well as human health hazards free tool effective against okra shoot and borer control.