Geographical Distribution of Clavibacter michiganensis subsp michiganensis in Serbia

During 2006 and 2007, an extensive survey for the canker pathogen was conducted in the major tomato growing districts in Serbia (Leskovac, Lebane, Padinska Skela, Sabac, Trstenik, Ub, Stara Pazova, Cacak) in order to estimate the infested area and disease incidence. Sixty bacterial strains were isolated from the diseased leaves, stems, fruits and seeds with dilution plating on the nonselective (NA, NBY) and semiselective media (D(2)ANX, mSCM and mCNS). The investigated strains were identified as C. michiganensis subsp. michiganensis based on biochemical characteristics, hypersensitive response in four-o'clock plant leaves and pathogenicity test on tomato seedlings. Amplification of DNA fragments of 614 bp in the first PCR protocol and DNA fragments of 270 bp in the second, confirmed that the investigated strains belonged to C. michiganensis subsp. michiganensis. The first wilt and canker symptoms were recorded in greenhouses in southern Serbia, in June 2006 on tomato cvs. 'Belle' and 'Magnus'. Further survey of greenhouse and field grown tomatoes in 2006 and 2007 resulted in additional findings of the disease in three other tomato growing regions in greenhouses on tomato cvs. 'Delfine' and 'Trogir' and in one region on the field grown tomato cv. 'Hector'. Disease incidence in greenhouses ranged from 2 to 50% while it reached 100% in the field, resulting in heavy losses. However, in spite of the fact that the results of these investigations showed the geographical distribution of C. michiganensis subsp. michiganensis in Serbia, further monitoring of this pathogen in tomato crops is neccesary considering its quarantine status.