Biological control of Clavibacter michiganensis subsp. sepedonicus
Studies have been carried out in Canada in order to evaluate antagonistic bacteria for suppression of Clavibacter michiganensis subsp. sepedonicus (EPPO A2 quarantine pest). Several bacterial strains (88 strains) with a potential for biological control have been isolated from the surface of potato tubers and selected on the basis of in vitro antibiosis to C. m. sepedonicus. These strains have then been tested in the glasshouse on micropropagated plantlets of potato, inoculated with C. m. sepedonicus. As a result, 8 strains consistently prevented infection of potato plantlets. Three strains which showed a high potential for biological control were respectively identified as a saprophytic enteric bacterium, an Arthrobacter sp. and a soil coryneform bacterium. These three strains have been tested in a field trial on small plots by inoculating (cutting with a contaminated knife) seed potato tubers with C. m. sepedonicus and antagonists. During the growing season, potato plants were then inspected for ring rot symptoms and samples were tested by ELISA. Results obtained are encouraging as the relative number of ring rot-free progeny tubers was generally greater when antagonistic bacteria were present. However, the authors pointed out that further studies are needed, in order to better identify these antagonistic bacteria and to test whether low incidence infections can be controlled in large-scale field experiments.
Sources
Gamard, P.; De Boer, S.H. (1995) Evaluation of antagonistic bacteria for suppression of bacterial ring rot of potato.
European Journal of Plant Pathology, 101 (5), 519-525.