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.
5
0
6
6
Description:
A Thesis
Submitted to the Faculty of Agriculture,
Sher-e-Bangla Agricultural University,
Dhaka, in partial fulfillment
of the requirements
for the degree
of
MASTER OF SCIENCE
IN
PLANT PATHOLOGY
SEMESTER: JANUARY-JUNE, 2017
