PM 7/42 (3) Clavibacter michiganensis subsp. michiganensis.
This Standard describes a diagnostic protocol for C. michiganensis subsp. michiganensis, which is now present in all main areas of production of tomato and is quite widely distributed in the EPPO region. The diagnostic procedure for symptomatic plants comprises isolation from infected tissue on non-selective and/or semi-selective media, followed by identification of presumptive isolates including determination of pathogenicity. This procedure includes tests which have been validated (for which available validation data is presented with the description of the relevant test) and tests which are currently in use in some laboratories, but for which full validation data is not yet available. Two different procedures for testing tomato seed are presented. In addition, a detection protocol for screening for symptomless, latently infected tomato plantlets is presented in Appendix 1, although this method has yet to be fully validated. A culture is identified as C. michiganensis subsp. michiganensis when a positive result is obtained for at least two tests based on different characteristics of the pathogen (e.g. combinations of biochemical, serological or molecular tests) or two molecular tests based on different DNA sequence targets in the genome.