Indigenous plant extracts and entomopathogenic fungus against aphids infesting broccoli

Abstract

Field trials were conducted in a replicated randomized block design at Mondouri, a Horticultural Research Station of Bidhan Chandra Krishi Viswavidyalaya, Nadia, West Bengal during 2008–09 and 2009–10, to assess the efficacy and economics of two indigenous plant products viz. seed extracts of Strychnos nuxvomica (Loganeaceae) and Pachyrrhizus erosus (Papilionaceae), using petroleum ether as solvent and an entomopathogenic fungus, Beauveria bassiana, against the aphids, viz., Lipaphis erysimi (Kalt.) and Myzus persicae (F.) on ‘Grand Sino’ a variety of broccoli. Both the extracts were used at 2.0 ml, 3.0 ml and 4.0 ml/lit of water, while for B. bassiana, these were 2.0 g, 2.5 g and 3.0 g/lit of water. Besides untreated control, emamectin benzoate 5% SG was used at 0.25 g, 0.50 g and 0.75 g/lit of water, for comparison. S. nuxvomica, when used @ 4.0 ml/lit. of water, resulted in 86.82% reduction of aphids with yield of 120.50 q/ha. B. bassiana and P. erosus, both @ 3.0 g/lit. and 4.0 ml/lit. of water were found to produce 84.18% and 83.52% reduction in population and yield of 111.55 q/ha and 104.25 q/ha, respectively. As high as 88.10% reduction in population was achieved with emamectin benzoate @ 0.75 g/lit. of water with yield of 133.77 q/ha. None of the tested products exhibited phytotoxicity for an observation period of 10 days after spraying. Emamectin benzoate @ 0.75 g/lit. of water recorded the highest economic return, giving a B: C ratio of 18.16: 1, followed by 16.70: 1 due to S. nuxvomica @ 4.0 ml/lit. of water, 16.28: 1 due to B. basssiana @ 3.0 g/lit. of water, and 14.34: 1 due to P. erosus @ 4.0 ml/lit. of water.