We examined the effect of the inoculation of Pseudomonas fluorescense FPH9601 on the incidence of several soil-borne diseases of tomato. A lower degree of disease occurrence was observed, compared with seedlings without treatment, when ca 10^6 cells/ml of tomato crown (foot) and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici was inoculated to P. fluorescense FPH9601 treated with seedlings. When the inoculum concentration of the pathogen increased to ca 10^7 cells ml^<-1>, the disease occurred severely in both cases, but the severity was lower in the FPH-treated seedlings. Furthermore, the number of diseased plants decreased by approximately half when F. oxysporum f. sp. lycopersici (race1) was inoculated to FPH-treated seedlings. Similarly, when Verticillium dahliae was inoculated to FPH-treated seedlings, the disease tended to remain milder, confirmiry the suppressive effect. In addition, examination of the plant height of seedlings inoculated with V dahliae revealed that the suppression of growth was approximately 20% in the FPH-treated seedlings, while approximately 40% in the untreated seedlings, respectively, indicating the remarkable suppressive effect on the disease. On the other hand, the suppressive effect induced by FPH inoculation was not observed in the case of Southern blight caused by Sclerotium rolfsii and damping-off caused by Rhizoctonia solani.
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