ECO-FRIENDLY MANAGEMENT OF PESTS OF OKRA THROUGH ORGANIC MANURES AND BIO-PESTICIDES
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Date
2011-04
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Abstract
Investigations were carried out on “eco-friendly management of pests of okra through organic manures and bio-pesticides” at Instructional Farm, College of Agriculture, Junagadh Agricultural University, Junagadh during Summer 2009 and 2010. During the study, jassid [Amrasca biguttula biguttula (Ishida)], whitefly [Bemisia tabaci (Gennadius)] and shoot and fruit borer [Earias vittella (Fabricius)] were found the major insect pests and mite, Tetranychus urticae (Koch) was the non-insect pest infesting the okra crop. Among the biological control agents, the coccinellids [Coccinella septempunctata Linnaeus, Harmonia axyridis (Pallas) and Cheilomenes sexmaculata (Fabricius)], green lacewing [Chrysoperla carnea (Stephens)] and spider [Tegenaria agrestis (Walckenaer)] formed the major group.
ABSTRACT
Studies on eco-friendly management of pests of okra through organic manures revealed that maximum (75%) requirement of the nitrogen by the crop applied through the neem cake combined with the inorganic fertilizers recorded the minimum population of jassid, whitefly and mite as well as also the minimum yellow vein mosaic disease intensity, fruit infestation on number and weight basis. While, farm yard manure (FYM) recorded the maximum population of natural enemies. Maximum yield of healthy okra fruits was recorded in the treatment where 75 per cent of the recommended dose of nitrogen was applied through neem cake. Considering the effect of organic manures on morphological characters of okra, the treatment where 50 per cent of the required nitrogen was applied through poultry manure and remaining through inorganic form recorded the maximum plant height, number of leaves per plant, number of flowers per plant, number of fruits per plant and fruit length (cm). The studies on relationship between pest population and morphological characters of okra revealed that plant height, number of leaves per plant and fruit length exhibited the positive correlation with the population of jassid, whitefly, mite and natural enemies and the yellow vein mosaic disease intensity. While, number of flowers per plant and number of fruits per plant showed negative correlation with population of jassid, whitefly and mite. All the morphological characters showed a negative correlation with the per cent fruit infestation on both the number and weight basis.
Bio-efficacy of bio-pesticides against of pests of okra revealed that endosulfan 0.07 per cent, neem seed kernel extract (NSKE) 5 per cent and neemazal 0.005 per cent were found most effective against the okra jassid, whitefly, mite with minimum
yellow vein mosaic disease intensity and minimum fruit infestation of both number and weight basis. All these treatments were found safer to the natural enemies. The bio-pesticides, Beauveria bassiana @ 2.0 kg/ha, Verticillium lecanii @ 2.5 kg/ha and Metarrhizium anisoplae @ 2.5 kg/ha proved the next effective group against the pests with increased mortality and safer to natural enemies. Significantly the maximum yield of healthy okra fruits was recorded in the treatment of spinosad 0.01 per cent. On the basis of overall rank values, the descending order of insecticides was spinosad 0.01 per cent, endosulfan 0.07 per cent, neemazal 0.005 per cent, NSKE 5 per cent, emamectin benzoate @ 5 g/10 litre, cartap hydrochloride 0.1 per cent, Bacillus thuringiensis @ 2.0 kg/ha, B. bassiana @ 2.0 kg/ha, V. lecanii @ 2.5 kg/ha and M. anisoplae @ 2.5 kg/ha. Considering the cost benefit ratio of these insecticides, neemazal 0.005 per cent gave the highest cost benefit ratio. The descending order of different treatments regarding the cost benefit ratio may be neemazal 0.005 per cent, endosulfan 0.07 per cent, NSKE 5 per cent, B. bassiana @ 2.0 kg/ha, spinosad 0.01 per cent, V. lecanii @ 2.5 kg/ha, cartap hydrochloride 0.1 per cent, M. anisoplae @ 2.5 kg/ha, B.t. @ 2.0 kg/ha and emamectin benzoate @ 5 g/ 10 litre. Looking to the effectiveness and economics of different organic manures and bio-pesticides applied for the control of major pests of okra, nitrogen requirement of the crop applied through the organic manures followed by two sprays of endosulfan 0.07 per cent or neemazal 0.005 per cent or NSKE 5 per cent proved to be the most effective eco-friendly management strategies against the major pests of okra.