Bacterial canker is the most important bacterial disease of tomato. The causal organism is Clavibacter michiganensis subsp. michiganensis (Cmm) and this bacterium can be intro-duced by contaminated seeds. For the detection of Cmm, toma-to seeds are first soaked in buffer. Then a stomacher is used for the release of bacteria from the seeds. After the concentra-tion of the bacteria, dilution plating on two semi-selective media is performed. SCM medium is such a semi-selective media. Actually, there are several modifications in use con-cerning the used carbon source, LiCl and the addition of antibi-otics. This medium is used in combination with D2ANX medi-um (D5128). After dilution plating suspected isolates are trans-ferred to YDC. Finally the identity of suspected isolates is determined by a pathogenicity test or PCR. The colonies of Clavibacter michiganensis subsp. michiganensis on SCM are small, light to dark grey, glistening, fluidal and often irregularly shaped. For detailed information about Duchefa’s Phytopathological media have a look at our specialized brochure about this topic. Brochure can be found at the “Brochure section” at the home page of this website.