Screening of maize genotypes against stem borers and their management with newer insecticides
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Date
2016
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Acharya N.G. Ranga Agricultural University
Abstract
Studies on the field screening (rabi 2013-14 and rabi 2014-15) of twenty two
maize genotypes including two checks to identify resistant genotypes against the maize
stem borers were conducted. These genotypes were further tested for morphological
and bio chemical plant characters for resistance against stem borers. Survey in Guntur
district for stem borers and its natural enemies in rice fallow maize were conducted.
Studies were also conducted to study the influence of different nitrogen levels on stem
borers and evaluation of certain newer insecticides against stem borers at Agricultural
College farm, Bapatla, Guntur, Andhra Pradesh, India.
Based on the intensity of damage score against stem borers, six genotypes, viz.,
ST X BM 254-1, Dhk 12 X 5321, ST X BM 32, ST X 5422, ST X BM 258-1 and ST X
BM 59-3 were resistant. The genotypes P3596, Dhk 12 X CM 1504, DHM 117, Dhk 12
X CM 142, ST X 5311, ST X 5416, ST X BM 254-3 and Dhk 12 X CM 151 were
moderately resistant. The genotypes ST X BM 59-1and P3396 are intermediate
resistant.
Among the resistant maize genotypes, STX BM 254-1, Dhk 12X 5321, STX
BM 32 and STX BM 258-1 exhibited high level of resistance against the damage
parameters viz., dead hearts, leaf damage, plant infestation, larval population, tassel
damage, cob borers, exit holes and tunnel length.
Among the various plant morphological characters viz., plant height, number of
nodes, trichome density, stem diameter, cob height, seed weight and dry matter showed
significant and negative correlation with the no. of larvae and plant infestation, where
as internodal length has showed significant positive correlation with no. of larvae and
plant infestation. The bio-chemical plant characters viz., nitrogen, carbohydrates and
proteins showed significant and positive correlation, while phenols showed significant
negative correlation with damage parameters caused by stem borers.
Surveys conducted in rice fallow maize during rabi 2013-14 and rabi 2014-15
in Guntur district revealed that only spiders (Agriope spp, Phidippus sp, Oxyopes spp,
Xyticus spp, etc) and coccinellids (Chilonemus sexmaculata, C. septumpunctata and
Cycloneda spp) were recorded among the predators and the highest per cent of dead
hearts were recorded at Kakumanu and Vemuru mandals.
The damage parameters like plant infestation, leaf damage, stem borer larval
population, dead hearts, exit holes and tunnel length were found to be highest with high
nitrogen levels (N6 (210 kg/ha) followed by N5 (180 kg/ha), N4 (150 kg/ha), N3 (120
kg/ha), N2 (90 kg/ha), NI (60 kg/ha) and N0).
Among the insecticides tested, carbofuran, flubendiamide and indoxacarb were
the most effective insecticides against maize stem borers with the highest per cent
reduction of population over untreated control. The grain yield was highest in
flubendiamide treated plots which was on par with carbofuran and indoxacarb. Among
the insecticides tested flubendiamide, spinosad, emamectin benzoate and indoxacarb
were safest and recorded the highest number of natural enemies viz., spiders and
ladybird beetles. The incremental cost benefit ratio was found to be highest with
carbofuran followed by flubendiamide.
Description
D5264
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