Biological control of tomato bacterial spot by seed microbiolization

Six plant growth promoting rhizobacteria isolates - two Streptomyces (DFs1296 and DFs1315), three Bacillus (DFs1414, DFs1420 and DFs1423) and one Pseudomonas (DFs1421) - were used to microbiolize tomato seeds for the control of bacterial spot caused by Xanthomonas gardneri. Three assays were conducted in a completely randomized design with six replications. In each assay, X. gardneri suspensions (10(8)CFUmL-1) were spray-inoculated on the leaves. In the first and second assays, three and four leaves, respectively, were assessed for disease severity. In the third assay, three leaves per plant were assessed for the number of lesions per leaf, leaf area and dry weight. Results showed that one of the Bacillus sp. isolate (DFs1420) consistently provided the greatest relative reduction (48%) of tomato bacterial spot severity.