Gravi epifizie di ceppi Sw-5 resistance-breaking di Tomato spotted wilt virus su pomodoro in Puglia

In 2015, canning tomato plants grown in open fields in the Province of Foggia (Apulia, southern Italy) showed severe symptoms of necrosis on stems and fruits making them unmarketable already by the end of June-mid of July. Disease incidence ranged between 80 and 100% of plants. Infection of a Sw-5 resistance-breaking strain of Tomato spotted wilt virus (TSWV-RB) was detected consistently in all symptomatic samples collected from different fields by means of molecular hybridization with a Digoxigeninlabelled DNA probe. No other viruses common in Italian tomato crops were detected. Virus was characterized as Sw-5 resistance-breaking on the basis of MaeI restriction pattern of RT-PCR amplicons obtained from NSM gene and mechanical inoculation onto the Messapico and Faino tomato varieties that are resistant to the common strains of TSWV. In a field fruits of some plants showed chocolate spotlike symptom but also in this case only TSWV was detected. Thus the etiology of the epiphytotic could be attributed to a Sw-5 resistance-breaking of TSWV. Basic information on the eco-epidemiology of TSWV is provided together with possibilities of control by prevention.