SCREENING OF SWEET POTATO GENOTYPES AGAINST WEEVIL, Cylas formicarius (Fab.) (BRENTIDAE: COLEOPTERA) AND IT’S MANAGEMENT
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Date
2020
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University of Horticultural Sciences, Bagalkot. (College of Horticulture, Bagalkot).
Abstract
Screening for identification of biophysical and biochemical traits of sweet potato
genotypes which imparts resistance against sweet potato weevil, Cylas formicarius (Fab.)
(Brentidae: Coleoptera) and its management was carried out at Regional Horticultural
Research and Extension Centre, Dharwad, Karnataka during 2019-2020. The results from the
screening for identification of biophysical traits of thirty sweet potato genotypes revealed that
the genotypes, BSP-39, BSP-36, BSP-1 and Shree bhadra were found to be resistant in
recording minimum per cent infestation, highest neck length of vine, minimum infestation
length and lowest mean weevil population. Whereas, BSP-32, BSP-31, BSP-33, BSP-28,
BSP-24, BSP-30, BSP-38, BSP-38, BSP-34 and BSP-23 were recorded as moderately
resistant genotypes. Further, the genotypes, BSP-26, BSP-8 and BSP-15 were found to be
moderately susceptible. Genotypes, BSP-10, BSP-19 and BSP-25 were highly susceptible to
sweet potato weevil. The biochemical traits like reducing sugar, phenol and starch in tubers
which were negatively correlated with level of susceptibility to weevil. Whereas, crude
protein and beta carotene in tubers were significantly positive correlation with per cent tuber
infestation.
Among the different IPM modules for management of sweet potato weevil in the local
sweet potato variety, Shree bhadra, Integrated module comprising of i) Soil application of
neem cake 250 kg ha-1
in last ploughing before ridge and furrow making, ii) Dipping the vine
cuttings in Imidacloprid 17.8 % SL @ 0.5 ml /l for 10 minutes before planting, iii) Earthing
up/ re-ridging the crop @ 30 and 60 DAP, iv) Installation of Synthetic sex pheromone traps
@ one per 100 m2 v) Root zone application of Beauveria bassiana @ 10 g/ kg of FYM @ 45
DAP, vi) Foliar spray of Emamectin Benzoate 5% SG @ 0.2 g/l @ 65 DAP recorded
significantly lower weevil population in vine and tuber, highest male adult weevils trap catch
per week, lowest damaged tubers, highest marketable tuber yield and higher net return with
highest B:C ratio than Bio-intensive module. Whereas, chemi-intensive module and foliar
spay of Malathion 50 % EC @ 2 ml/l were recorded less effective in managing sweet potato
weevil.