Detection of Clavibacter michiganensis subsp. sepedonicus in daughter tubers of volunteer potato plants

Daughter tubers of volunteer potatoes were tested for their ability to maintain Clavibacter michiganensis subsp. sepedonicus (Cms). In different areas of the CR, volunteer potatoes were searched for in crops grown in rotation with potatoes and where one or two years before Cms had been detected and identified in samples of harvested seed or commercial potatoes using the test scheme in accordance to EC Directive 93/85/EEC. During May and June of 2005 and 2006, emerging or emerged plants of volunteer potatoes were collected at nine locations of Bohemia and transplanted to the experimental field in the Diagnostic Service Laboratory at Šluknov-Kunratice in Northern Bohemia. The daughter tubers of these plants were harvested and stored at 6°C for 1 month and then at 22°C for 3 months for multiplication of Cms cells. Samples of the daughter tubers were divided into 215 partial samples and tested for the occurrence of Cms at five terms which differed in length of storage time. The DAS ELISA test was used to detect Cms in the tuber samples. Cms was detected in eight of the nine potato volunteer tuber samples from different locations. The presence of Cms in positively tested tuber samples was confirmed using a pathogenicity test on eggplants (Solanum melongena). The optimal time for the detection of the pathogen in the harvested daughter tubers was between 4 and 10 weeks of storage at 22°C.