Integrated management of TYLCV/TYLCSV on greenhouse hydroponic tomatoes in Southern Italy

Tomato yellow leaf curl (TYLC) caused by Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl Sardinia virus (TYLCSV), vectored by the whitefly Bemisia tabaci, is a major disease of tomato in Sardinia and Sicily, and is becoming a serious threat in Southern Italy too. TYLCSV was first reported in Calabria region in 1991, but apparently it was an occasional outbreak, and B. tabaci was not detected. Later, during the 2003-2004 winter, a serious epidemic was observed in protected tomato crops in Castrovillari, Cosenza province. TYLCV was first described in Sicily in 2003 and during 2004 in continental Italy. Both viruses were detected in winter 2005-2006 on the Basilicata Ionic coast, in the Metapontum area, both in protected and in open field tomato crops. Experiments were conducted in Calabria Region, Southern Italy, under controlled conditions in a group of greenhouses where several tomato crops were grown hydroponically to determine the separate and integrated effects of UV-reflective mulch (UVRM), Acibenzolar-S-methyl (Actigard) and the two insecticides Imidacloprid (ADMIRE 2F) and Thiamethoxam (ACTARA 25WG). Highly UV-reflective mulch covered plots were treated with Actigard and insecticides, both alone or in combination. TYLC disease incidence was determined from late August 2005 to late January 2006. The highly UVRM alone was effective in reducing disease incidence of about 28.6% at the end of October, and of 31.7% at the end of January. However, Actigard with UVRM significantly reduced TYLC disease incidence to 70% and 48.5%, in 2 months and 5 months after the first treatment, respectively. The insecticides with UVRM, resulted in a moderate reduction of disease incidence (22.5%) at the end of October. At the end of January a reduction in disease incidence due to insecticide applications was not significant. The use of Actigard combined with the insecticides on UVRM reduced the disease incidence (63.4% with Admire and 56.1% with Actara) at the end of January. Actigard alone or with insecticides on UVRM was effective in reducing disease incidences. Highly UVRM and Actigard were effective in reducing the primary spread of TYLCV/TYLCSV in greenhouse hydroponic tomatoes. Comparative analysis of their effects at different periods post-treatment suggests that multiple applications of Actigard may be necessary to reduce progress of this disease.