EVALUATION OF DIFFERENT DOSES OF TWO SELECTED INSECTICIDES FOR CONTROLLING THE INSECT VECTOR (WHITE FLY) OF OKRA YELLOW VEIN MOSAIC VIRUS (OYVMV)

Abstract

A field experiment on okra was conducted at the Field Laboratory, Department of Plant Pathology, Sher-e- Bangla Agricultural University, Dhaka-1207, during March to July, 2016. The aim of the study was to evaluate the performance of two selected insecticides viz. Imitaf and ACmix in different spray schedules (1-6 sprays) against Yellow vein mosaic virus (YVMV) of okra for controlling the insect vectors. The treatments were T

(control/no spray), T 1 (1 spray), T 2 (2 spray), T 3 (3 spray), T 4 (4 spray), T (5 spray) and T (6 spray). The insecticides spraying started from 20 DAS (days after sowing) and continued with 5 days interval. The lowest percent disease incidence was recorded in T 6

(15.98%, 16.71%) at 95 DAS respectively for Imitaf and ACmix. The highest percent disease incidence was found in T (88.21% and 89.27% respectively). In case of morphological features; number of leaves, flowers and fruits per plant was also recorded the highest in T 6 0 (50.00, 29.00, 28.33 for Imitaf and 50.33, 30.00, 30.00 for ACmix) up to last harvesting. In case of yield and yield contributing characters, significant variation was found among the treatments. The highest yield per plant and plot was recorded in T

(6 sprays) treatment in case of both the insecticides application (0.83kg/plant, 15.44 kg/plot for Imitaf and 0.82kg/plant, 15.04 kg/plot for ACmix). The highest plant height was recorded in T in both experiment (129.92 cm and 127.51 cm respectively). In case of physiological features, the highest chlorophyll content was also measured the highest in T 6 6 (57.93 μ mol m -2 s -1 and 56.55 μ mol m -2 s -1 , respectively). Plant height and yield showed the positive relationship with chlorophyll content and percent disease incidence showed negative relationship with chlorophyll content. The yield of okra was decreased with the increase of percent disease incidence. However, considering the fungicidal cost, T 4 (4 sprays) was the best in case of all measuring parameters.

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