Pongamia oil soap for the management of major pests of chilli (Capsicum annum L.)
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Date
2020
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Department of Agricultural Entomology, College of Agriculture, Padannakkad
Abstract
The efficacy of the pongamia oil soap was tested at different concentrations in controlling the major pests of chilli, viz., whitefly, aphid (Aphis gossypii Glover) and mite (Polyphagotarsonemus latus Banks) under the project entitled ‘Pongamia oil soap for the management of major pests of chilli (Capsicum annuum L.)’.
Laboratory bioassay was conducted to evaluate the effective repellency and oviposition repellency of pongamia oil soap against the adults of solanum whitefly, Aleurothrixus trachoides Back. Net house study of whitefly was performed in the Department of Agricultural Entomology, College of Agriculture, Padannakkad. Treated and control plants were randomly placed in a net house and whiteflies were released on the next day morning. There were seven treatments (T1: Pongamia oil soap 3%; T2: Pongamia oil soap 2%; T3: Pongamia oil soap 1%; T4: Pongamia oil soap 0.6%; T5: Soap solution 0.5%; T6: Water spray; T7: Control) with three replications. Number of adult whiteflies settled and eggs laid on the leaves in the treated and control plants were counted on the 1st, 3rd, 5th and 7th day after release and the repellence was computed. Statistical design CRD was used for the assessment of data obtained.
Effective repellence and oviposition repellence of pongamia oil soap against the whitefly were directly proportional to concentration and indirectly proportional to time. The plants treated with pongamia oil soap effectively repelled the whitefly from settling over the treated surface. The 3% pongamia oil soap was found superior with 86.10% repellence one day after the release of whiteflies and it was followed by the 2% pongamia oil soap. All the concentrations of pongamia oil soap showed 100% repellence on the first day after the release and prevented egg laying. Pongamia oil soap (3%) was highly effective with 72.24 % oviposition repellence even after 7 days of spray.
Field study was carried out at Instructional farm II of College of Agriculture, Padnnakkad at Karuvacheri during November 2019 to May 2020. The variety used was Vellayani Athulya. The statistical design followed was RBD with eight treatments and
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three replications. The following are the treatments applied - T1: Standard check – Spiromesifen 22.9 SC @ 96 g a. i. / ha; T2: Pongamia oil soap 3%; T3: Pongamia oil soap 2%; T4: Pongamia oil soap 1%; T5: Pongamia oil soap 0.6%; T6: Neem oil soap 0.6%; T7: Soap solution 0.5%; T8: Control. The treatments were applied three times in the field at 2, 3 and 5 months after transplanting. Major sucking pests (whitefly, aphid and mite) and the natural enemies (spiders, coccinellids and predatory mites) were counted in the field study. Observations were made one day prior and 1, 3, 5, 7 and 14 days after treatment for the pests and natural enemies. Damage symptoms like leaf curling and malformed fruits were counted 7 and 14 days after the treatments.
Spiromesifen was found effective against the sucking pests of chilli and showed persistent action in the field, whereas pongamia oil soap reported an immediate control over the pests but its effectiveness declined with time and concentration. Among the botanicals, 3% pongamia oil soap was found effective against whitefly, aphid and mite and was followed by the 2% per cent pongamia oil soap. Pongamia oil soap proved its effectiveness against these pests up to seven days after the treatment and the effect declined by 14 days after the spray. The soap solution (0.5%) always reported high population of pests compared to other treatments indicating that soap has no role in the effect of pongamia oil soap. Pongamia oil soap was found safe to spiders and coccinellids. But it reduced the population of predatory mites in the field. Leaf curl index and per cent fruit malformation recorded the minimum value in standard check and pongamia oil soap (3%) sprayed plots. This shows that these treatments are the highly effective against mites. Thrips infestation was negligible in the field and thus it was not recorded.
Maximum fruit length was recorded from the standard check followed by pongamia oil soap 3 per cent treated plot. Standard check and pongamia oil soap 3 per cent exhibited higher fruit yield and marketable yield. Standard check recorded the highest BC ratio among the treatments. Economics of pongamia oil soap (3%) in terms of BC ratio was also high as compared to other treatments and control. All the concentrations of pongamia oil soap showed slight phytotoxicity when it was applied during extreme summer months. The study shows that pongamia oil soap is effective in protecting chilli crop from sucking pests and can be a component in chilli IPM.
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