Efficacy of four phosphate-mobilizing bacteria applied with an animal bone charcoal formulation in controlling Pythium aphanidermatum and Fusarium oxysporum f.sp. radicis lycopersici in tomato Joeke Postma a,⇑ , Francesca Clematis a,b , Els H. Nijhuis a , Edward Someus c a Plant Research International, P.O. Box 69, 6700 AB Wageningen, The Netherlands b University of Turin, Centre of Competence for the Innovation in the Agro-Environmental Sector, Grugliasco, Italy c Terra Humana Ltd., Széchenyi u. 59, H-1222 Budapest, Hungary highlights  Biological control of Pythium aphanidermatum and Fusarium oxysporum in tomato.  Bacteria with the capacity to mobilise phosphate were able to control plant diseases.  Animal bone char can function as a novel carrier for biocontrol agents.  Pseudomonas chlororaphis has high root colonizing capacity. graphical abstract article info Article history: Received 14 December 2012 Accepted 8 July 2013 Available online 19 July 2013 Keywords: Pseudomonas Bacillus Paenibacillus Streptomyces Biological control Root colonization Soil-borne diseases abstract Four taxonomically different bacteria, with the ability to mobilize phosphate (P) and to colonize animal bone charcoal (ABC), were tested for their capacity to control plant pathogens. Tests were performed in the greenhouse with young tomato plants in (potting) soil and in rockwool. Plants were infested with Pyth- ium aphanidermatum and Fusarium oxysporum f.sp. radicis-lycopersici (FORL) causing respectively damping off and crown and root rot. ABC is a porous, phosphorous containing waste product from the food industry, and was used as carrier to introduce the bacteria into the growing media. Scanning electron microscopy (SEM) pictures showed the intensive colonization of the bacteria in the interior of ABC. Of the four tested strains, Pseudomonas chlororaphis 4.4.1 was most effective in controlling the diseases. It controlled P. aphanidermatum and FORL in tomato in each of the tests. The strain appeared to be a very good root col- onizer, since 1–8% of the cultural bacterial population on the tomato roots or in rhizosphere soil consisted of the introduced strain. Population densities of P. chlororaphis 4.4.1 were 0.5–5  10 7 CFU g 1 root or rhi- zosphere soil. Peanibacillus polymyxa 12.4.1 and Streptomyces pseudovenezuelae 13.4.2 significantly con- trolled P. aphanidermatum in two tests in potting soil, whereas Bacillus pumilus 4.4.2 was not effective. FORL could be controlled by B. pumilus 4.4.2 and S. pseudovenezuelae 13.4.2 in only part of the tests, whereas P. polymyxa 12.4.1 was not effective. ABC is a novel carrier for delivery of biocontrol bacteria into soil or substrate and combines biocontrol with recycling a phosphorous-rich waste product. Ó 2013 Elsevier Inc. All rights reserved. 1. Introduction The continuing growth of the world population and increasing pressure on all resources used for agricultural production demand action to improve sustainability in agriculture. Chemical inputs should be replaced by other strategies to avoid harmful emissions and residues. Synthetic pesticides can be successfully reduced by the application of biological control agents. Increasing numbers of products have been developed in recent years (Glare et al., 2012). Nevertheless, the biopesticide market is still a small portion 1049-9644/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.biocontrol.2013.07.002 ⇑ Corresponding author. E-mail address: joeke.postma@wur.nl (J. Postma). Biological Control 67 (2013) 284–291 Contents lists available at ScienceDirect Biological Control journal homepage: www.elsevier.com/locate/ybcon