An outbreak of bacterial cancer was observed in tomato fields in the main tomato growing area of Apulia and Basilicata regions, respectively in the campaigns of Foggia and Matera province, in 2010 summer, starting 20-30 days from transplant. Symptoms of systemic wilt of the plant, necrosis of the leaf margin and upward curling of the leaf edges, dark streaks on stems and stem cankers, spots with raised brown centers and external marbling on fruits surrounded by an opaque white halo were observed in open field in the period following to blooming. The disease reached, in some instances, above all at the beginning of ripening, a 100% incidence, with the complete loss of the crop. Detection assays for Clavibacter michiganensis subsp. michiganensis were performed in order to ascertain the etiologic agent, in any case of symptom observation. The diagnostic procedure comprised isolation from infected tissue, presumptive diagnosis with a rapid test, identification of presumptive isolates and determination of pathogenicity. All symptomatic plants resulted infected with the bacterium under investigation. They belonged always to the same cultivar of tomato, 'Uno Rosso', and to the same seed batch. This led us to believe that bacterial infection was associated with tomato seed. The suspected tomato seed batch 'Uno Rosso' was analyzed using the method for the detection of C. michiganensis subsp. michiganensis on tomato seed (International Seed Federation), working on a slight modification because the seeds under investigation were pills. The result was that the seeds were positive to C. michiganensis subsp. michiganensis. About 40 millions of these tomato pills (100 kg tomato seeds) were distributed, with imaginable consequences on plant health of the industrial tomato crops. This event allowed us to reflect on how important is the use of health seed for the preservation of our agro-systems.
