Seed testing method for Clavibacter michiganensis subsp. michiganensis
A reliable method for the detection of Clavibacter michiganensis subsp. michiganensis (EPPO A2 quarantine pest) has been reported from The Netherlands. The method is based on rapid screening of tomato seed lots by indirect immunofluorescens staining (IF) followed by dilution plating of IF positive seed lots and a further pathogenicity test on tomato seedlings. To extract the bacteria from the seeds, the seeds were either blended with a stomacher or soaked for 24-48 h at 4-6ø C. Dilution platings were carried out on SCN, KTB and modified CNS media and it was found that the SCN medium was in general the more selective medium. The confirmation of suspected colonies with yeast dextrose carbonate medium, IF and a pathogenicity test were extremely reliable (P;0,95). The authors recommended for routine testing of seed lots to screen tomato seedlots after soaking seeds for 24 h at 4-6ø C with IF, followed by plating of IF positive seed lots on modified CNS and SCM after soaking seeds for another 24 h.
Sources
Franken, A.A.J.M.; Kamminga, G.C.; Snijders, W.; Van der Zouwen, P.S.; Birnbaum, Y.E. ;(1993) ;Detection of Clavibacter michiganensis ssp. michiganensis in tomato seeds by immunofluorescence microscopy and dilution plating.
Netherlands Journal of Plant Pathology 99, 125-137.