Studies on defoliators and stemfly pests of soybean and their management
Loading...
Date
2013
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
UAS Dharwad
Abstract
Investigations were carried out on different insect pests of soybean at ARS,
Bailhongal and MARS, UAS, Dharwad, Karnataka during kharif, 2010-11 and 2011-12.
Survey was under taken in four districts of northern Karnataka viz., Dharwad,
Belgaum, Haveri and Bagalkot during kharif 2010 and 2011. Among districts surveyed,
Belgaum and Bagalkot were identified as hot spots for stem fly while Dharwad and Belgaum
were identified as hot spots for defoliators by recording higher incidence. The surveillance in
fixed plot study indicated the highest incidence of Melanagromyza sojae during 36th and 37th
Meteorological Standard Week (10.10 and 15.00%, respectively). The population of
Spodoptera litura ranged from 2.50-3.45 larvae/meter row length, Thysanoplusia orchalcea
fom 1.05-1.82 l/mrl and Spilarctia oblique from 1.30-2.15 l/mrl and activity of natural
enemies observed on 15 days after sowing.
Correlation studies between insect pests and weather parameters revealed that, rainfall
had negative correlation (r = 0.55) and maximum temperature (r = 0.71) had positive
correlation with S. litura and M. sojae.
Seed dressing with thiamethoxam 70 WS @ 3.0 g/kg seed + foliar spray of
thiamethoxam 25 WG @ 0.5 g/l at 20 days after sowing proved its superiority over other
treatments in managing stem fly by recording high seed yield of 25.64 and 24.42 q/ha during
2010 and 2011, respectively. Among the insecticide, flubendiamide 480 SC 0.2 ml/l was
found to be the most effective in managing leaf eating caterpillars by recording highest seed
yield of 23.95 q/ha. The simulation studies revealed that 25 per cent defoliation at 20 DAG
did not significantly affect the seed yield while at 60 days after germination it was
significantly educed the seed yield.
Among the genotypes screened for two years PS-1466 and PK-1042 were found
resistant to stem fly and high yielding. While JS-335 and Dsb-11 susceptible to high yielding
and defoliation as per max-min and min-max method.