INCIDENCE AND MANAGEMENT OF SOME MAJOR INSECT PESTS OF OKRA

Abstract

The present experiment was conducted at the laboratory of Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka during the period from April to August, 2012 to evaluate the efficacy of synthetic insecticides and botanical product against okra shoot and fruit borer and white fly. The treatments were comprised of seven synthetic chemical insecticides one botanical product and one untreated control and these were T1 =Spraying of Actara 25WG @1g/L of water at 7 days interval; T2 = Spraying of Neem oil @ 3ml/L of water at 7 days interval; T3 = Spraying of Decis 2.5 EC @1ml/L of water at 7 days interval; T4 = Spraying of Shorbicron 450 EC @ 2ml/L of water at 7 days interval; T5 = Spraying of Suntap 50 WP @1.2g/L of water at 7 days interval; T6 = Spraying of Ripcord 10 EC @1.5ml/L of water at 7 days interval; T7 = Marshal100 EC @1.5ml/L of water at 7 days interval; T8= Quinalphos @ 2ml/L of water at 7 days interval and T8 = Untreated Control. The experiment was laid out in single factor Randomized Complete Block Design (RCBD) with three replications. The data were recorded on shoot infestation; fruit infestation by number and weight at early, mid and late fruiting stages; plant and yield related attributes as well as yield of okra and also on the incidence of white fly. Among eight treatments, Ripcord 10EC reduced the highest percent of shoot infestation (59.68%) over control at fruiting stage followed by Actara 25WG (52.85%), whereas Neem oil showed the least performance (11.51%). In case of plant infestation, Ripcord 10EC reduced the highest percent of plant infestation (27.41%), whereas Neem oil showed the least performance (4.15%). In case of fruit infestation by number and fruit infestation by weight, Ripcord 10EC reduced the highest percent of fruit infestation 45.30% and 45.49% respectively over control at different stages, followed by Actara 25WG 35.34% and 31.61% respectively, whereas Neem oil showed the least performance (10.91% and 4.91% respectively). In term of incidence of whitefly and leaf infestation by Okra Yellow Vein Clearing Mosaic Virus, Ripcord 10EC reduced the highest percent (45.29% and 31.22% respectively), whereas Neem oil showed the least performance (8.50% and 3.33% respectively). Considering plant and yield related attributes, Ripcord 10EC increased the highest percent of plant height (77.33%), fruit length of healthy & infested fruits were 67.37% and 87.73%, girth of healthy & infected fruits were 35.03% and 85.20% respectively, over control followed by Actara 25 WG, Suntap 50 WP, Marshal 100 EC, Quinalphos, Decis 2.5 EC and Shorbicron 450 EC, where Neem oil showed the least performance. Similarly the highest fruit yield (13.77 ton/ha) was also achieved by Ripcord 10EC with the increase of 242.51% yield over control than Actara 25 WG and other tested insecticides, whereas Neem oil showed the least performance (6.340 ton/ha) with the lowest percent yield increase (57.76%). Okra yield was increased due to increases of fruit length, girth and plant height; on the other hand fruit yield was decreased due to increase of fruit infestation by number and weight occurs to OSFB. Thus Ripcord 10EC could be considered as an effective tool against okra shoot and fruit borer.