POPULATION DYNAMICS AND MANAGEMENT OF GROUNDNUT DEFOLIATORS, 2748
Loading...
Files
Date
2018-09
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
JAU, JUNAGADH
Abstract
An investigation was carried out on population dynamics and management of
groundnut defoliators during the kharif season of the year 2017 at College of Agriculture,
Junagadh Agricultural University, Junagadh.
Studies on population dynamics of the groundnut defoliator revealed that the
incidence of H. armigera commenced from the 4
th week of July indicating 0.12
larvae/plant, which gradually increased and attained a first peak of 1.53 larvae/plant
during the 3rd week of August. Later on, it started to decline slightly. But during 1st week
of September, the pest population increased and formed second peak of 1.73 larvae/plant
and then continuously decreased with 0.16 larvae/plant in the 2nd week of October and
then disappeared. Population of H. armigera exhibited a non significant positive
correlation with morning relative humidity, evening relative humidity, mean relative
humidity and minimum temperature, significant negative correlation with maximum
temperature and mean temperature. Whereas, pest population showed a non significant
negative correlation with maximum temperature, mean temperature, wind speed, mean
bright sun shine hours, evaporation rate, rainfall and rainy days.
The incidence of S. litura commenced from the 4
th week of July indicating 0.24
larvae/plant, which gradually increased and attained a first peak of 1.78 larvae/plant
during the 3rd week of August. Later on, it started to decline slightly. But during 1st week
of September, the pest population increased and formed second peak of 1.35 larvae/plant
and then continuously decreased with 0.26 larvae/plant in the 2nd week of October and
then disappeared. Population of leaf eating caterpillar exhibited a non significant positive
correlation with morning relative humidity, evening relative humidity, mean relative humidity and minimum temperature. Whereas, pest population showed a non significant
negative correlation with maximum temperature, mean temperature, wind speed, mean
bright sun shine hours, evaporation rate, rainfall and rainy days.
Significantly the highest pod (2410 kg/ha) and fodder (4473 kg/ha) yield as well
as CBR of 1:15.52 was obtained in the plot treated with insecticides. The avoidable yield
loss due to groundnut defoliators was recorded to the tune of 42.12 per cent in pod and
41.25 per cent in fodder in untreated plot. The data on per cent in yield increase in
protected plots revealed that 72.76 per cent in pod and 70.21 per cent in fodder yield was
increased over unprotected plot.
Spinosad 0.01 per cent and quinalphos 0.05 per cent were found most effective in
reducing the larval population of H. armigera and S. litura. Among the bio-pesticides, the
B. bassiana 0.007 per cent and Bacillus thuringiensis 1.1 kg/ha were found most
effective. Whereas, the treatments of L. lecanii 0.007 per cent, M. anisopliae 0.007 per
cent, azadirechtin 0.000375 per cent, panchagavya 3 per cent and pongamia oil 1 per cent
were found less effective for control of both pests.
Considering the pod yield, the treatment with spinosad 0.01 per cent gave the
highest pod yield of 2500 kg/ha and found at par with quinalphos 0.05 per cent which
recorded 2430 kg/ha pod yield. In case of fodder yield, treatment with spinosad 0.01 per
cent gave the highest fodder yield of 4687 kg/ha and was found statistically at par with
quinalphos 0.05 per cent (4618 kg/ha). The highest per cent increase in pod (63.71 per
cent) and fodder (73.65 per cent) yield of groundnut over control was recorded in the
treatment of spinosad 0.01 per cent.
Considering the economics of these insecticides, quinalphos 0.05 per cent gave
the highest cost benefit ratio (1:22.69) followed by B. bassiana 0.007 per cent (1:13.05)
and spinosad 0.01 per cent (1:10.77) may be need for the control of defoliators in
groundnut.