EFFECT OF TIME OF SOWING ON DISEASE INCIDENCE OF OKRA YELLOW VEIN MOSAIC VIRUS (OYVMV) AND ITS MANAGEMENT THROUGH SELECTED INSECTICIDES AND LIGHT REFLECTING COLORED MULCHES

Abstract

A field experiment was conducted at the central farm of Sher-e-Bangla Agricultural University, Dhaka-1207, during March to August, 2018. The aim of the study was to investigate the time sowing effect on disease incidence of Okra Yellow Vein Mosaic Virus (OYVMV) in selected okra variety, and to evaluate the effect of light reflecting colored mulches and only one time spraying with selected insecticides to control the insect vector whitefly (Bemisia tabaci). The experiment was carried out in three blocks layouted with RCBD comprising three different sowing times and eight treatments viz. T (control/no spray), T 1 (1 time spray with imitaf), T 2 (1 time spray with protect), T (1 time spray with tiddo plus), T 4 (1 time spray with terbine), T (light reflecting silver color mulch),T 6 (light reflecting red color mulch) and T 7 5 (light reflecting black color mulch) with three replications. The mulches were used before sowing and insecticides were sprayed at 30 DAS. It was observed that among the sowing time, the lowest disease incidence (22.56 %) was found in first sowing (15 th March) and the highest disease incidence (59.00%) was recorded in third sowing (15 th April) at 80 DAS. Among the light reflecting colored mulches, the lowest disease incidence (11.48%) was recorded in the plots which mulched with red color mulch (T ). Among the insecticides, the lowest disease incidence (30.17%) was recorded in plots that was sprayed with terbine (one time).Yield and yield contributing characters, morphological and physiological features of okra plant that changes due to disease infection which cause damages in okra production and reduce the fruit quality as well as market value was also the part of this study. Yield and yield contributing characters showed significant variance among the three different sowing times and selected treatments. The highest yield per plant (0.73 kg) and plot (3.88 kg) was obtained in first sowing. Among the light reflecting mulches, the highest yield per plant (0.92 kg) and plot (4.85 kg) was obtained in the plots that covered with red colored mulch (T 6 6 ). Among the selected insecticides, the highest yield per plant (0.82 kg) and plot (3.18 kg) was obtained in the plots that sprayed with terbine (one time). Among different light reflecting colored mulches and insecticides, the highest plant height (95.86 cm and 95.35 cm) was found in red color mulched plots (T ) and in the plots that was sprayed with terbine (one time) respectively. In the relationship study, it was noticed that the yield and plant height was showed negative relationship with disease incidence. However, considering the all measuring parameters, maintaining sowing time with combining the treatments; spraying with terbine (one time) and used red color mulch may be recommended as good management approaches that will give higher okra production and lower disease incidence of Okra Yellow Vein Mosaic Virus (OYVMV).