A method for detection of seedborne bacterial diseases in tomato seeds

A method for detection and quantitative estimation of tomato seedborne pathogenic bacteria has been developed. It enables detection in a 7 g tomato seed sample of as few as ten colony-forming units per gram tomato seeds of the following seedborne pathogens of tomato:Pseudomonas syringae pv. tomato,Pseudomonas corrugata, Xanthomonas campestris pv.vesicatoria, andClavibacter michiganense subsp.michiganense. With representative seed samples, the method employs dry grinding, weighing, bacterial extraction and quantitative calculation on selective or semi-selective medium. The efficiency of this method was tested by diluting pathogen-free seed lots with naturally or artificially infested tomato seeds. This procedure enables one to determine the minimal threshold of pathogen which can be detected by this method on media, in comparison with the percentage of diseased seedlings developed from the same seed lots in the growth chamber or in the greenhouse.