Pongamia oil soap for the management of major pests of brinjal (Solanum melongena L.)
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Date
2020
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Department of Agriculture, College of Agiculture, Padannakkad
Abstract
Brinjal is highly nutritious and most demanding vegetable in India as it can be grown throughout the year. The crop is prone to various pest incidence which is considered to be the major yield limiting factor. The un-scientific, irrational and over use of chemical insecticides in vegetables crops lead to many negative sequences. Hence the present research work ‘Pongamia oil soap for the management of major pests of brinjal (Solanum melongena L.)’ was undertaken during 2019-20 with the aim of evaluating the potential of a new product pongamia oil soap at four different concentrations on major brinjal pests viz., fruit and shoot borer (FSB), leafhopper, hadda beetle, aphids, red spider mites and brinjal whiteflies. The influence on natural enemies was also recorded. Laboratory experiment on evaluation of pongamia oil soap was carried out at Department of Agricultural Entomology, College of Agriculture, Padannakkad during 2019-20 for the antifeedant and growth retardation property against Epilachna grubs (Epilachna dodecastigma). Fourth instar grubs and first instar grubs were used to study the feeding deterrence index (FDI) and growth retardation index (GI and RGI) with seven treatments: Pongamia oil soap @ 3% (T1), Pongamia oil soap @ 2% (T2), Pongamia oil soap @ 1% (T3), Pongamia oil soap @ 0.6% (T4), Soap solution @ 0.5% (T5), Water spray (T6) and Control (T7) under Completely Randomised Design (CRD) with three replications. Hundred per cent antifeedant activity on fourth instar grubs of Epilachna was observed under pongamia oil soap 3 per cent treatment. Maximum growth retardation property also observed by 3% pongamia oil soap (RGI of 0.00) which caused death of grubs at first instar itself among the different treatments. It was followed by pongamia oil soap 2%, 1%, 0.6% with 94.35, 92.07 and 90.48% FDI and 0.08, 0.16 and 0.32 RGI respectively. Field evaluation of pongamia oil soap was carried out at Instructional farm II, Karuvachery, CoA, Padannakkad under Randomised Block Design (RBD) with eight treatments and three replications on Surya variety. The treatments imposed in field study were: Chlorantraniliprole 18.5 SC @ 3 mL/10L (Spray I and III) & Thiamethoxam 25 WG @ 2g/10L (Spray II) (T1); Pongamia oil soap @ 3% (T2); Pongamia oil soap @ 2% (T3); Pongamia oil soap @ 1% (T4); Pongamia oil soap @ 0.6% (T5); Neem oil soap @ 0.6% (T6); Soap solution @ 0.5% (T7) and Control (T8). Observations for the damage symptoms caused by FSB and hadda beetles were made at 1 DBT, 7 and 14 DAT. For the sucking insect and mite pests, count was made on 1 DBT, 1, 3, 5, 7 and 14 DAT. Totally three sprays were given during rabi season 2019-20. Fruit infestation caused by fruit and shoot borer was effectively reduced by pongamia oil soap @ 3% and @ 2% during all the three sprays. Minimum fruit damage was observed on seventh day after spray (12.94% on 7 days after third spray) by 3% pongamia oil soap followed by chlorantraniliprole. The efficacy of chlorantraniliprole was persisted up to 14 DAS while efficacy of pongamia soap reduced gradually. The leafhopper incidence was effectively controlled by the application of pongamia oil soap @ 3% during first and second spray. Maximum reduction in leafhopper population was recorded by thiamethoxam followed by pongamia oil soap (3%, 2%, 1% and 0.6%) and neem oil soap. Among botanicals, pongamia oil soap @ 3% was the most effective treatment against hadda beetle incidence followed by chlorantraniliprole and thiamethoxam. Maximum efficacy by pongamia oil soap was observed on 7DAS and it was reduced on 14 DAS. Neem oil soap and pongamia oil soap at 0.6% were statistically on par with each other except during first spray. Aphid colonies were significantly reduced in 3% pongamia oil soap followed by thiamethoxam, 2%, 1% and 0.6% pongamia oil soap. Maximum population reduction was recorded on one day after treatment. Pongamia oil soap @ 3% was the superior treatment against red spider mites which was immediately followed by pongamia oil soap @ 2%, 1% and 0.6%. Pongamia oil soap 3% was equally effective as thiamethoxam in reducing the population density of whiteflies then the lower doses tested and neem oil soap @ 0.6%. Effectiveness of the pongamia oil soap was reduced with time and lower concentrations. Soap solution @ 0.5% didn’t affect any pest incidence. Spider population recorded maximum in pongamia oil soap @ 0.6% treated plants over control while pongamia oil soap was statistically at par with control in coccinellids, syrphids and lacewings count at all the concentrations. Hemipteran predators and hymenopteran parasitoids count recorded highest in control plot and all other treatments found to be at par with control except thiamethoxam. Pongamia oil soap (3, 2, 1 and 0.6%) was at par with control in predatory mite population. Average fruit length was high in pongamia oil soap @ 3% treated plants (8.53 cm) followed by standard check (8.49 cm), pongamia oil soap @ 2%, 1% and 0.6% and neem oil soap @ 0.6%. Standard check recorded highest fresh and marketable yield over control followed by pongamia oil soap @ 3%. Benefit Cost ratio was also high in standard check followed by 3% pongamia oil soap as compared to control plot showing its potential to be a good biopesticide and IPM component in brinjal cultivation.
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175068