Studies on seasonal incidence, varietal screening and eco-friendly management of insect pest complex of pigeonpea at Pantnagar, Uttarakhand
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Date
2022-09
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G. B. Pant University of Agriculture and Technology, Pantnagar
Abstract
The present study was carried out on the seasonal incidence, varietal screening of local genotypes/varieties of pigeon pea and evaluation of biorational formulations against major insect pest complex of Pigeon pea under field conditions during the kharif crop seasons 2019-20 and 2020-21 at the Norman Borlaug Crop Research Centre of G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand. The seasonal incidence of total number of nineteen insects was observed attacking the pigeon pea crop during both the kharif crop seasons. Among them, leaf beetle, leaf folder, looper larvae and cow bugs were found the most significant threats when the plants were still in their vegetative stage. Leaf beetle (1.66 beetles/plant) was recorded during 34 MSW whereas leaf folder (5.10 leaf folds/plant) was attained during 41 MSW with the least population of semiloopers (0.48 larvae/plant) during 33 MSW. Cow bug (1.47 bugs/plant) during 35 MSW. Spotted pod borer, gram pod borer and pod bug, Clavigralla gibbosa were observed during the reproductive stage and contributed in crop's losses. The mean population of spotted pod borer (26.70 webs/plant) was observed during 39 MSW, gram pod borer during 46 MSW (8.51 larvae/plant) and commencement of pod bugs (9.20 /plant) was recorded during 46MSW. Under varietal trial, on the basis of significantly less insect pest population, pod damage, seed damage and high grain yield, out of 29 elite genotypes/varieties of pigeonpea, 05 i.e. PA659, PA663, PA669, PA421 and PA674 were found the least susceptible to pod borers . As the mean Maruca webs /plants were least in genotype PA659(12.45), PA663(11.90), PA669(10.20), PA421(8.42) and PA674(12.27). The overall mean of H. armigera larvae/plant was less in genotypes PA659, PA663, PA669, PA421 and PA674 with 1.70,1.75,2.35,1.45 and1.72, respectively. The overall number of mean pod bugs/plant were recorded the least in 5.17,4.80,3.90,4.73 and 4.55 genotypes PA659,PA663, PA669,PA421 and PA674, respectively. The least cumulative mean pod damage with least PRR values was recorded in PA659 (24.66)(PRR-3), PA421(29.17)(PRR-4), PA674(29.96)(PRR-4)and PA670(31.26) )(PRR-4) and the least per cent seed damage was recorded in PA666(12.55), PA659(14.30) and PA421 (16.50) with the maximum grain yield was obtained in genotypes PA659 (767kg/ha) followed by PA666(659kg/ha) and PA421(622kg/ha). A total number of two sprays were carried out during the field experiments to study the efficacy of biorationals against spotted pod borer, gram pod borer and their associated natural enemies. Among the biorationals applied, Azadirachtin 1500 ppm @ 5 ml/ l was found very effective to minimize the web-counts of spotted pod borer and larval population of H. armigera and resulted in the minimum cumulative per cent pod damage (25.50) with the highest grain yield (1110 kg/ha).However, in case of insecticide application, Chlorantraniliprole 18.5 SC 30g a.i/ha resulted in the lowest mean per cent pod damage (21.00) with grain yield of (1190 kg/ha). All of the tested biorationals were found safe for natural enemies in comparison to chemical treatment. The highest cost benefit ratio of 9.70 and 5.00 were calculated for Bt var kurastaki and Azadirachtin 1500 ppm @ 5 ml/l, respectively. Therefore, on the basis of the findings obtained under the field studies, it can be concluded that resistant varieties along with eco- friendly biorational sprays can easily be incorporated in IPM program for pod borer complex on pigeonpea.