STUDIES ON SEASONAL INCIDENCE, AVOIDABLE YIELD LOSS AND MANAGEMENT OF SUCKING PESTS IN BLACKGRAM (Vigna mungo (Linn.) Hepper.)
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Date
2018
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PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
The present investigation entitled “Studies on seasonal incidence, avoidable
yield loss and management of sucking pests in blackgram (Vigna mungo (Linn.)
Hepper.)” was conducted during rabi 2017-18 at students farm, College of Agriculture,
Rajendranagar, Hyderabad.
The results on seasonal incidence of sucking pests of blackgram indicated that
the population of sucking pests in rabi blackgram were started from 2nd week after
sowing and their population were high during the vegetative stages and reached its peak
during the reproductive stage and later declined. The correlation studies between
leafhoppers and weather parameters revealed that the maximum temperature, rainfall
and evening relative humidity showed non significant positive correlation with the
leafhopper population, whereas minimum temperature, rainy days and sunshine hours
showed non significant negative correlation, while morning relative humidity and
evaporation showed significantly positive correlation whereas wind speed showed
significantly negative correlation.
Correlation between whiteflies and weather parameters revealed that the
maximum temperature, morning relative humidity and sunshine hours showed
significantly positive correlation with the whitefly population, whereas evaporation
showed significantly negative correlation, whereas minimum temperature and rainy
days showed non significant negative correlation, while evening relative humidity,
rainfall and wind speed showed non significant positive correlation with the whitefly
population. The correlation between thrips and weather parameters revealed that the
maximum temperature and minimum temperature showed non significant positive
correlation with the thrips population, whereas morning relative humidity, rainfall and
rainy days showed non significant negative correlation, while evening relative humidity
and sunshine hours showed significantly negative correlation whereas wind speed
showed significantly positive correlation.
Multiple linear regressions equations developed for the sucking insect pests in
blackgram with one week lag weather parameters during rabi 2017-18 revealed that all
the weather parameters collectively influenced the sucking pest population in the range
between 92 to 95 per cent.
Estimation of avoidable yield losses due to sucking pests in blackgram during
rabi 2017-18 revealed that the avoidable reduction in plant height, number of branches
per plant, pods per plant, number of seeds per pod due to insecticides application was
19.14, 19.78, 20.70 and 17.80 per cent respectively and a significantly higher yield was
obtained in protected plots i.e. 1028 kg ha-1
, while, comparitively low yield i.e. 759 kg
ha-1 was recorded from unprotected plots. The yield increased in protected plots over
unprotected was 269 kg ha-1
i.e. 35.44 per cent. The avoidable yield loss was 26.16 per
cent by spraying of insecticides i.e. monocrotophos 36 SC and fipronil 5% SC at ten
days intervals against sucking pests viz.,whiteflies, thrips, aphids and leafhoppers in
blackgram.
Among all the insecticides tested imidacloprid WS 70 at 5 g kg-1 was found to
be the most effective treatment which was followed by thiamethoxam 25 WG at
3 g kg-1
, imidacloprid 17.8 SL at 10 ml kg-1
, acetamiprid 20 SP at 15 g kg-1
, carbosulfan
25 EC at 30 ml kg-1
and dimethoate 20 EC at 5 ml kg-1
against leafhopper and thrips
population in rabi blackgram.
Thiamethoxam 25 WG at 3 g kg-1 was found to be the most effective against
whiteflies which was followed by imidacloprid 70 WS at 10 ml kg-1
, acetamiprid 20 SP
at 15 g kg-1
and imidacloprid 17.8 SL. The least effective insecticides were carbosulfan
25 EC at 30 ml kg-1
and dimethoate 20 EC at 5 ml kg-1
but were found to be superior
over the untreated control.
There was no significant difference in the seed treatment with different
insecticides against percent germination, initial and final plant stand except dimethoate
20 EC at 5 ml kg-1
treated plots and untreated control plots which recorded the lowest.
The increase in plant height was found to be in the order of imidacloprid 70 WS at 5 g
kg-1
, thiamethoxam 25 WG at 3 g kg-1
and imidacloprid 17.8 SL at 10 ml kg-1
and they
were on par with each other and these insecticides were followed by carbosulfan 30 EC
at 30 ml kg-1
, acetamiprid 20 SP at 15 g kg-1
and dimethoate 20 EC at 5 ml kg-1 which
were on par with each other and lowest plant height was observed in the untreated
control plots.
Seed treatment with insecticides increased the number of branches per plant in
all the insecticidal treatments and the range was found to be 4.53 and 3.20. The highest
number of branches per plant was seen in plots treated with imidacloprid 70 WS at
5 g kg-1
and least number of branches per plant was found in control plots. The highest
pod yield was recorded in plots treated with imidacloprid WS 70 at 972.00 kg ha-1
followed by thiamethoxam 25 WG at 833.37 kg ha-1
, acetamiprid 20 SP at 805.60 kg
ha-1
, imidacloprid 17.8 SL at 764.27 kg ha-1
, carbosulfan 25 EC at 722.23 kg ha-1
and
dimethoate 20 EC at 652.67 kg ha-1
and the lowest pod yield was recorded in control
plots at 583.33 kg-1
.
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Citation
D10,282