BIOLOGY, CROP LOSS ESTIMATION AND VARIETAL SCREENING FOR PIGEONPEA LEAF WEBBER, Grapholita
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Date
2013-06-30
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UNIVERSITY OF AGRICULTURAL SCIENCES RAICHUR
Abstract
Studies undertaken at College of Agriculture, Gulbarga during 2012-13 on biology, crop loss estimation, and varietal screening of pigeonpea leaf webber, Grapholita critica (Meyr.) revealed that female leaf webber laid eggs singly and occasionally in groups on both the surfaces of leaves maximum being laid on the lower surface of leaves near midrib. The freshly laid eggs were flattened, oval, transparent, dull white and round at both ends. The larva had four instars with a mean larval duration of 18.35 days. The total life cycle of male and female was 35.96 and 37.38 days, respectively with a mean fecundity of 55.80 eggs per female. Larvae were also seen damaging pods of pigeonpea, besides folding of leaves.
The incidence of leaf webber was started in one month old crop and continued till the end of vegetative stage, thereafter leaf webber population became sparse. The incidence of leaf webber started in the month of August but the peak infestation of leaf webber was noticed in the September month coinciding with the peak vegetative growth of the crop. The incidence of leaf webber was high in the crop sown at end of June, early July and less in the crop sown at end of July and early August. Only the maximum temperature had shown a significant negative correlation with number of webs.
To estimate the yield loss in pigeonpea (Maruthi variety) differential population of leaf webber viz., 0, 1, 2 4, 6, 8 and 10 were released inside the cages starting from treatment one to treatment seven. The results of crop loss estimation studies revealed that lowest yield (838.33 kg/ha) was recorded in treatment seven followed by treatment six (851.91 kg/ha). The lowest per cent yield loss (0.15 %) observed in treatment two and highest per cent yield loss (5.69 %) recorded in treatment seven.
Fifty three pigeonpea genotypes were screened against leaf webbber, G. critica of which 11 MLT-MD, 18 AICRP and 24 under ICRISAT trials. Based on overall performance TS 3R C4, Asha, RVSA 81, Rajeev lochan, P-703, RVSA 34, RVSA 64, RVKT 260, WRG-181, ICP 13212, WRG 157, WRG 98 and ICPHRL 4979-7 were categorised as promising genotypes against leaf webber.
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