Analysis of spatial spread of two Begomoviruses, TYLCV and TYLCSV, in tomato hydroponics in Calabria region, Italy.

Tomato yellow leaf curl Sardinia virus (TYLCSV), one of the whitefly-transmitted Begomoviruses, is a worldwide and spreading threat for cultured tomatoes. It was first reported in Calabria Region in 1991, but apparently it was an occasional outbreak, and Bemisia tabaci was not detected. Later, during the 2003-2004 winter season, a serious epidemic was observed in protected tomato crops in Castrovillari, Cosenza Province. Tomato yellow leaf curl virus (TYLCV) was first described in Sicily in 2003 and only recently in continental Italy, during 2004. The present study was performed in a group of greenhouses where several tomato crops are grown hydroponically. The tomato yellow leaf curl disease spread within each greenhouse was investigated weekly, monitoring the appearance of key symptoms (yellowing, leaf curling and stunting) during the period from September (time of crop planting in greenhouse) to January. DAS-ELISA, performed using a broad-spectrum reagent combination (distributed by Bioreba AG), confirmed the presence of TYLCSV and/or TYLCV in symptomatic plants. In order to discriminate between the two Begomoviruses, PCR/RFLP analysis was performed on infected plants. In order to evaluate the presence of the virus vector in the greenhouse, whitefly B. tabaci chromotropic traps were used. The results of the spatial spread of the disease within the greenhouses are reported.