Impact of agronomic practices on incidence of different insect pests and their management in high density planting of cotton
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Date
2014-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
AGRICULTURAL ENTOMOLOGY DEPT., N.M. COLLEGE OF AGRICULTURE, NAVSARI AGRICULTURAL UNIVERSITY, NAVSARI
Abstract
Investigations on “Impact of agronomic practices on
incidence of different insect pests and their management in high density
planting of cotton” were carried out at the Main Cotton Research Station,
Surat
during
Kharif
2013-14.
Eighteen treatment
combinations
comprising three spacings viz., 120x45 (S1), 60x15 (S2) and 45x15 cm
(S3), two genotypes i.e. GSHV-01/1338 and GBHV-164 and three levels
of nitrogen viz., 100, 125 and 150 per cent of recommended nitrogen
(RDN) were evaluated with ETL based interventions in factorial
randomized block design with three replications.
Among the three spacings, closer spacings (45x15 and 60x15
cm) attracted more aphid, thrips, leafhopper, whitefly and mealy bug
under study as compared to recommended spacing (120x45 cm). Further,
the closer spacing of 45x15 cm recorded significantly higher population
of thrips, leafhopper and mealy bug than closer spacing of 60x15 cm
whereas the population of aphid and whitefly did not differ significantly
between the closer spacing of 60x15 and 45x15 cm. Closer spacings
(45x15 and 60x15 cm) attracted more natural enemies as compared to
wider spacing (120x45 cm). Further, closer spacing of 45x15 cm recorded
significantly higher population of lady bird beetle and spiders than closer
spacing of 60x15 cm whereas the parasitism of mealy bug by A.
bambawalei did not differ significantly between the closer spacings of
60x15 and 45x15 cm. With respect to Chrysoperla population, there was
no significant difference in population at different spacings. With respect
to bollworms, closer spacings (45x15 and 60x15 cm) concerned more
larval populations of bollworms except American bollworm (ABW) as
compared to wider spacing (120x45 cm). Further, the closer spacing of
45x15 cm recorded significantly higher population of spotted bollworm
(SBW) than closer spacing of 60x15 cm whereas the population of pink
bollworm (PBW) did not differ significantly between the closer spacing
of 60x15 and 45x15 cm. Damage to square and green bolls by bollworms
were not affected at different spacings whereas damage to open and
locule at harvest found significantly high at closer spacings. However,
locule damage did not differ significantly between the closer spacing of
60x15 and 45x15 cm. The closer spacing of 45x15 cm recorded higher
seed cotton yield than closer spacing of 60x15 cm and both were found
superior than the recommended spacing (120x45 cm). The average spray
was 6.0 and 5.5 in closer spacings of 45x15 cm and 60x15 cm as against
5.0 in normal spacings of 120 x45 cm. and 5.0 against insect pests at ETL
populations. The maximum net return (Rs. 51170.1/ha) and benefit cost
ratio (2.36) was realized in closer spacing of 45x15 cm followed by other
closer spacing of 60x15 cm with net return of Rs.45415.5 per hectare and
BCR of 2.24 as against minimum net return of Rs.35895.3 per hectare
and BCR of 2.19 in normal spacing (120x45 cm).
Aphid, thrips and mealy bug was found significantly high on
GBHV-164 than GSHV-01/1338, whereas, leafhopper and whitefly
population were not influenced by genotypes. As regards to natural
enemies, mean population of lady bird beetle and spiders and parasitism
of mealy bug by A. bambawalei was found significantly high on GBHV-
164 than GSHV-01/1338 whereas population of Chrysoperla was not
affected. In case of bollworms, mean population of SBW was found
significantly high on GBHV-164 than GSHV-01/1338 whereas American
bollworm and pink Bollworm population statistically did not differ.
Damage to fruiting bodies is concerned; open boll damage was
significantly high on GBHV-164 than GSHV-01/1338, whereas, square
and green boll damage by American bollworm and spotted bollworm as
well as locule damage at harvest were not affected by genotypes. There
was no variation in seed cotton yield of GSHV-01/1338 and GBHV-164.
An average spray was 6.5 on GSHV-01/1338 as against 7.0 on GBHV-
164 for insect pest management. However, higher net return (Rs.
47001.6/ha) with high BCR (2.35) was obtained in GBHV-164 than
GSHV-01/1338 having net return of Rs.41319 per hectare and BCR of
2.19.
Amongst the three levels of nitrogen, high dose of nitrogen
application (125 and 150% RDN) involved more thrips, mealy bug, aphid
and whitefly as compared to recommended level (100% RDN), whereas,
leafhopper was not influenced by high nitrogen application. Thrips and
mealy bug population was responded more to 150 per cent RDN
compared to 125 per cent RDN. Aphid and whitefly were found at similar
level at the higher doses of nitrogen (125 and 150% RDN). The natural
enemies were not affected at different nitrogen applications. Higher
nitrogen application (125 and 150% RDN) concerned more bollworms.
ABW and SBW (larvae) were found significantly high at 150 per cent
RDN; whereas PBW did not differ significantly between the higher doses
of nitrogen (150 and 125% RDN). Increased nitrogen application did not
show any significant impact on bollworm damage to squares and bolls as
well as the open boll and locule damage at harvest. Seed cotton yield was
not influenced by different levels of nitrogen. Average number of spray
was 8.0 in each of 125 and 150 per cent RDN as against 7.5 in 100 per
cent RDN.
Higher net return (Rs. 46571.3/ha) and BCR (2.34) was
obtained under 125 per cent RDN as against net returns of Rs. 43702.7
per hectare and Rs. 42207 per hectare and BCR of 2.23 and 2.24 under
150 and 100 per cent RDN, respectively. Interaction: Spacing x Genotype
x Nitrogen was found non-significant with respect to aphid, thrips,
leafhopper and whitefly except mealy bug. The treatment combination
(S3G2N3) of sowing GBHV-164 at closer spacing of 45x15 cm with high
dose of nitrogen (150% RDN) recorded highest population, whereas,
recommended GSHV-01/1338 at recommended spacing of 120x45 cm
with 100 per cent RDN (S1G1N1) recorded lowest population of mealy
bug. Interaction was found non-significant with respect to populations of
Chrysoperla and spiders and parasitism by A. bambawalei except lady
bird beetle. The treatment combination (S3G2N3) of sowing GBHV-164 at
closer spacing of 45x15 cm with high dose of nitrogen (150% RDN)
recorded highest population whereas recommended GSHV-01/1338 at
recommended spacing of 120x45 cm with 100 per cent RDN (S1G1N1)
recorded lowest population of lady bird beetle. In case of bollworms and
its damage, interaction was found non-significant with respect to ABW,
SBW and PBW populations and square and green boll damage by ABW
and SBW as well as open boll damage and locule damage at harvest.
With respect to seed cotton yield, also, it was found non-significant. The
all treatment combinations with closer spacings required 8 ETL based
interventions as against 5 with normal spacing for insect pest
management.
The
treatment
combinations
of
S3G2N1
recorded
numerically higher seed cotton yield of 2110.3 kg per hectare with higher
net return of Rs. 58115 per hectare and BCR of 2.58 as against minimum
seed cotton yield of 1293.2 kg per hectare having net return of Rs. 28717
per hectare and BCR of 1.97 under treatment combination of S1G1N1.
Higher profitable seed cotton yield was found in the
treatment combination S3G2N1 comprising GBHV-164 sown at closer
spacing (HDPS) of 45x15 cm with 180 kg N per hectare (100% RDN).
Though, the incidence of insect pests remained high in above high density
planting than normal practice, they were effectively managed (based on
ETL) with two additional sprays for sucking pests (each one against
aphid and leafhopper) and one for bollworm (against American
bollworm) under present study.
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