Journal of Horticultural Sciences

A. Krishnamoorthy ¹, P. N. Ganga Visalakshi ¹, A. Manoj Kumar ², M. Mani ¹

Affiliations
1 Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore-560 089, IN
2 Department of Crop Physiology, UAS, GKVK, Bangalore- 560 065, IN

Abstract

An in vitro study was conducted to determine the interaction effect of ten pesticides tested at field recommended dose on conidial germination, vegetative growth and sporulation of Lecanicillium lecanii(ZIMM.) ZARE&GAMS. Compatibility of L. lecanii to different pesticides was found to be varied. Conidial germination was 99.3 and 85.7% in Pongamia oil and acephate, whereas, it was totally inhibited by the presence of chlorothalonil, iprodion + carbendazim, carbendazim and thiophanate methyl indicating that these pesticides were highly toxic. Dinocap recorded as moderately toxic while endosulfan, abamectin and ethion were least toxic based to the germination of conidia. So also Iprodion + carbendazim did not and carbendazim allow L. lecanii to put forth mycelium growth in their presence. Thiophanate methyl, Pongamia oil, acephate, endosulfan, ethion and chlorothalonil were observed to be innocuous pesticides registering growth of mycelium upto 2.33, 2.23, 2.23, 2.03, 2.03 and 2.00 cm dia., respectively, from 0.6 cm dia. held in the center of Petri plate on 14^th day after treatment. As far as sporulation is concerned, Pongamia oil alone recorded the maximum yield of 47.2x10⁶ conidia/ml followed by 18x10⁶ conidia/ml, in chlorothalonil as against 20x10⁶ conidia/ml in control, which means that the pongamia oil exhibited synergistic effect on L. lecanii, yielding more conidial spores. Thus, based on in vitro interaction study, pongamia oil alone was found to be safe to the entamopathogenic fungus L. lecanii in nature and iprodion + carbendazim and carbendazim were found to be highly toxic.

Keywords

Botanicals, Pesticides, Lecanicillium lecanii.

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A. Manoj Kumar ¹, Girija Ganesan ²

Affiliations
1 Department of Crop Physiology, University of Agricultural Sciences, G. K. V. K., Bangalore-560 065, Karnataka, IN
2 Division of Plant Pathology, Indian Institute of Horticultural Research, Hesseraghatta Lake Post, Bangalore-560 089, IN

Abstract

Biological control agents, Glomus mosseae IIHR, Bacillus subtilis IIHR-1, Pseudomonas fluorescens IIHR+3, Trichoderma harzianum IIHR P₁ and T. viride IIHR P₂₂ were evaluated against tomato wilt caused by Ralstonia solanacearum in pathogen-infested plots during 2003-2004. Microbial preparations were applied either as transplant ischolar_main dips or ischolar_main dip plus soil drench 30 days after transplanting. Per cent survivability increased with the use of all biological control agents tested. However, G. mosseae treated plants resulted in better survival (25.75 and 28.79% in ischolar_main dip alone and 60 and 66.67% in ischolar_main dip plus drench against untreated control 0 and 1.5% during 2003 and 2004 respectively), compared to the rest of the treatments, suggesting G. mosseae amendment to pathogen-infested soil would result in substantially higher plant survival against the untreated controls.

Keywords

Biocontrol Microorganisms, Bacterial Wilt, Survivability, Ralstonia solanacearum, Tomato.

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