Bacterial speck of tomatoes is caused by the bacterium Pseudomonas syringae pv. tomato (Pst). The bacterium can be introduced by the use of Pst-contaminated seeds. Therefore, detection of Pst in seeds of tomato is common. For the detection of Pst, seeds are first soaked in buffer. Then a stomacher is used for the release of bacteria from the seeds. The bacteria are concentrated by centrifugation. Then dilution plating on two semi-selectice media KBZ and KBBC is performed. Suspected colonies are transferred to KB and finally identified by PCR or a pathogenicity assay. Pst forms small, flat and pink-colored colonies on KBZ after ca. 5 days. For detailed information about DuchefaÃâs Phytopathological media have a look at our specialized brochure about this topic. Brochure can be found at the ÃâBrochure sectionÃâ? at the home page of this website.