Applied Soil Ecology 49 (2011) 215–223 Contents lists available at ScienceDirect Applied Soil Ecology journa l h o me page: www.elsevier.com/locate/apsoil Combining Pseudomonas, Bacillus and Trichoderma strains with organic amendments and micronutrient to enhance suppression of collar and root rot disease in physic nut P. Latha a , T. Anand a,∗ , V. Prakasam a , E.I. Jonathan b , M. Paramathma c , R. Samiyappan a a Department of Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore 641003, India b Department of Plant Nematology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore 641003, India c Tamil Nadu Agricultural University, Coimbatore 641003, India a r t i c l e i n f o Article history: Received 24 June 2010 Received in revised form 31 March 2011 Accepted 7 May 2011 Keywords: Bacillus subtilis Micronutrients Organic amendments Physic nut Pseudomonas fluorescens Trichoderma viride a b s t r a c t The fungal and bacterial biocontrol agents were tested individually and in combinations with oil cakes, organic manures and micronutrients for their efficacy against collar and root rot pathogen, Lasiodiplodia theobromae under in vitro, glasshouse and field conditions. Among the fungal (Trichoderma) and bacterial (Pseudomonas and Bacillus) antagonists screened against L. theobromae under in vitro conditions, Tricho- derma viride (Tv1), Pseudomonas fluorescens (Pf1) and Bacillus subtilis (Bs16) isolates exhibited maximum inhibition compared to other isolates. Among the oil cakes, organic manures and micronutrients tested in vitro against the pathogen, neem cake, farmyard manure (FYM) and zinc sulphate were most effective in reducing the growth of the pathogen. The compatibility studies revealed the isolate of T. viride (Tv1), P. fluorescens (Pf1) and B. subtilis (Bs16) were compatible with other and also with neem cake and zinc sulphate. Of the biocontrol agents tested individually as well as in mixtures with neem cake, FYM and zinc sulphate against L. theobromae, combination of Pf1 + Tv1 + Bs16 + neem cake + FYM + zinc sulphate showed maximum inhibition in mycelial growth of the pathogen. In glasshouse and field experiments also, the mixture of Pf1 + Tv1 + Bs16 + neem cake + FYM + zinc sulphate was found to be superior in reducing the collar and root rot disease incidence compared to other treatments. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Physic nut (Jatropha curcas L.,) is an important commercial bio- diesel plant species and is being advocated for development of waste land and dry land. It is one of the prospective oil yielding plants with vast industrial potential in the scene of energy crisis. The bio-diesel is non-toxic, biodegradable, increase the engine life with an advantage of safety in handling and storage. The oil is also useful for illumination without smoke, manufacturing lubricants, soaps, candle, resins, polish, paint, hair oil, liquefied petroleum gas (LPG) and furnace oil (Venkatesh and Lakshmipathaiah, 2008). Among the several constraints in physic nut cultivation, diseases play a major role in yield reduction and it is affected by many fun- gal and viral diseases. Among the fungal diseases, collar and root rot caused by Lasiodiplodia theobromae (Pat.) Griffon & Maubl (Syn: Botryodiplodia theobromae (Pat.) is an economically important soil borne disease (Prakasam, 2005). ∗ Corresponding author. E-mail address: barathiana@yahoo.com (T. Anand). Control of collar and root rot disease has been almost exclusively based on the application of chemical pesticides. Several effective fungicides have been recommended for use against this pathogen, but they are not considered to be long-term solutions, due to concerns of expense, exposure risks, health and environmental haz- ards, residue persistence and development of tolerance. There is a vital need for alternative methods of control for collar and root rot. So far, effective and ecologically sound management practices have not been developed for this disease. Therefore, one of the objectives of the current study was to develop a biological control strategy for this disease that is durable and is an alternative to agrochemicals. Several antagonistic organisms have been successfully used as biocontrol agents for controlling soil borne pathogens (Deacon, 1991). In most of the research, to date, biocontrol agents are applied singly to combat the growth of the pathogens. Although the potential benefits of a single biocontrol agent application has been demonstrated in many studies, it may also partially account for the reported inconsistent performance because a single biocontrol agent is not likely to be active in all kinds of soil environment and all agricultural ecosystems (Raupach and Kloepper, 1998). These have resulted in inadequate colonization, limited tolerance to changes in environmental conditions and fluctuations in production of 0929-1393/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.apsoil.2011.05.003