Detection of Clavibacter michiganensis subsp. michiganensis in symptomless tomato transplants

Clavibacter michiganensis subsp. michiganensis, the cause of bacterial canker, was isolated from symptomless tomato (Lycopersicon esculentum) seedlings that were surface-disinfested with 100% ethanol, sectioned, and pressed onto the surface of a semiselective medium (mCNS). In greenhouse tests, movement of bacteria down stems was variable 1-3 days after inoculation of the apical end of the stem, but by 7 days, C. m, michiganensis was isolated from sections at least 10 cm below the inoculation site of all plants. However, symptoms were not observed for 17 days (...)