SEASONAL ABUNDANCE, VARIETAL SCREENING AND MANAGEMENT OF WHITEFLY, Bemisia tabaci (Gennadius) INFESTING KHARIF OKRA, 2804
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Date
2019-06
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JAU, JUNAGADH
Abstract
Investigations on seasonal abundance, varietal screening and management of
whitefly, Bemisia tabaci (Gennadius) infesting kharif okra were carried out under
field condition during 2018 at Instructional Farm, College of Agriculture, Junagadh
Agricultural University, Junagadh. For the management of whitefly, ten different
varieties /genotypes were screened, different combinations of potash fertilizer and
foliar application of insecticides were evaluated against the pest.
The incidence of whitefly, B. tabaci was commenced from first week of
August and continued till first week of October having a single peak (7.52 whitefly
/leaf) during last week of September in okra crop. Whitefly population had significant
positive relation with maximum temperature (r= 0.613*) and bright sunshine hours
(0.802*). While, it had significant negative correlation with minimum temperature (-
0.700*), wind speed (-0.674*), morning relative humidity (-0.705*) and evening
relative humidity (-0.733*). While, it had non significant negative correlation with
rainfall (-0.377).
The lowest whitefly incidence was recorded in HRB-108-2 (1.65 whitefly
/leaf) and JOL-11-12 (1.94) genotypes of okra and was categorized as resistant (R).
While, the highest whitefly population was recorded in Pusa Sawani (5.09) variety
and it was categorized as susceptible (S). Absract
Based on both the sprays and pooled over period over sprays, whitefly can be
effectively managed by application of potash fertilizer dose @ 80 kg/ha followed by
spray application of acetamiprid 20 SP @ 0.006%. Interaction of potash fertilizer and
insecticidal spray was found effective in treatment of potash fertilizer @ 80 kg/ha +
acetamiprid 20 SP @ 0.006% followed by potash fertilizer @ 80 kg/ha + triazophos
40 EC @ 0.04% and potash fertilizer @ 80 kg/ha + diafenthiuron 50 WP @ 0.05%.
Whereas, potash fertilizer @ 60 kg/ha + acetamiprid 20 SP @ 0.006%, potash
fertilizer @ 60 kg/ha + triazophos 40 EC @ 0.04% and potash fertilizer @ 60 kg/ha +
diafenthiuron 50 WP @ 0.05% were found mediocre in their effectiveness. Potash
fertilizer @ 50 kg/ha + acetamiprid 20 SP @ 0.006%, potash fertilizer @ 50 kg/ha +
triazophos 40 EC @ 0.04%, potash fertilizer @ 50 kg/ha + diafenthiuron 50 WP @
0.05%, potash fertilizer @ 80 kg/ha + control and potash fertilizer @ 60 kg/ha +
control were found less effective.
The highest fruit yield (13106 kg/ha) was harvested in the plots treated with
potash fertilizer @ 80 kg/ha + acetamiprid 20 SP @ 0.006% followed by potash
fertilizer @ 80 kg/ha + triazophos 40 EC @ 0.04% (12782) and potash fertilizer @ 80
kg/ha + diafenthiuron 50 WP @ 0.05% (12088). As far as the per cent increase of
yield over control concerned, maximum yield was received with spray application of
potash fertilizer @ 80 kg/ha + acetamiprid 20 SP @ 0.006% (67.40%) followed by
potash fertilizer @ 80 kg/ha + triazophos 40 EC @ 0.04% (63.26%) and potash
fertilizer @ 80 kg/ha + diafenthiuron 50 WP @ 0.05% (54.40%).
The highest Incremental Cost Benefit Ratio (ICBR) was obtained from the
plots treated with potash fertilizer @ 80 kg/ha + acetamiprid 20 SP @ 0.006%
(1:27.66). While, in overall effectiveness of combinations, potash fertilizer @ 80
kg/ha + acetamiprid 20 SP @ 0.006% found most effective (first rank) followed by
potash fertilizer @ 80 kg/ha + triazophos 40 EC @ 0.04% > potash fertilizer @ 80
kg/ha + diafenthiuron 50 WP @ 0.05% > potash fertilizer @ 60 kg/ha + acetamiprid
20 SP @ 0.006% > potash fertilizer @ 60 kg/ha + triazophos 40 EC @ 0.04% >
potash fertilizer @ 60 kg/ha + diafenthiuron 50 WP @ 0.05% > potash fertilizer @ 50
kg/ha + acetamiprid 20 SP @ 0.006% > potash fertilizer @ 50 kg/ha + triazophos 40
EC @ 0.04% > potash fertilizer @ 50 kg/ha + diafenthiuron 50 WP @ 0.05% >
potash fertilizer @ 80 kg/ha + control > potash fertilizer @ 60 kg/ha + control and
potash fertilizer @ 50 kg/ha + control against B. tabaci in okra crop.