Integrated approach to TYLCD management in Sardinia (Italy).

In Sardinia (Italy) Tomato yellow leaf curl disease (TYLCD) re-emerged in 2003, after a period of decline, producing severe yield losses in protected tomato crops. This epidemic outbreak highlighted the inadequacy of the approach to TYLCD management based chiefly on the chemical control of its vector, the whitefly Bemisia tabaci, and the use of 40-mesh nets for greenhouse screening. To evaluate the reliability of alternative practices for implementation within IP&DM programmes, in 2007 and 2008 we carried out two field experiments on greenhouse tomato crops planted in summer. In both trials we tested the use of UV-reflective mulches (UVRM) or floating row covers (NWRC), against an uncovered control on clear mulch. Furthermore, we assessed the effectiveness of acibenzolar-S-methyl, a SAR elicitor, as subplot factor in a split plot design. In 2007 because of the low incidence of the disease it was not possible to assess differences among the treatments. However a significant increase in plant growth, and production was observed in UVRM plots. By contrast, in 2008 the study crop was seriously affected by TYLCD. In the plots not treated with acibenzolar-S-methyl, the disease progression was initially slowed down in NWRC and, to a lesser extent, in UVRM plots compared to control plots but, during the second month of the cropping period, the differences among treatments became statistically not significant. In the plots treated with acibenzolar-S-methyl the dynamics of TYLCD infection during the first five weeks exhibited the same trend as in the untreated plots. Thereafter, the combination of UVRM and, to a lesser extent, of NWRC with the SAR elicitor resulted in a reduction of disease incidence with respect to the control. In conclusion, all the control measures tested in the present work showed the potential for TYLCD management in greenhouse tomatoes. However, the most promising results were achieved using UV-reflective mulch and non-woven row cover in combination with acibenzolar-S-methyl. In view of its positive impact on plant growth and yield in summer planted tomato crops, as well as on TYLCD infection, the use of UV-reflective mulch warrants further investigation.