Screening Varieties for Resistance to Tomato Yellow Leaf Curl Virus

Tomato yellow leaf curl virus (TYLCV) is considered the worst tomato virus worldwide.  The disease is induced by a number of closely related begomoviruses transmitted by the whitefly Bemisia tabaci (Gennadius).  TYLCV infection may result in up to 90% flower abscission and highly reduced yields. Foliar symptoms include shortened internodes and dwarfed leaves, which are cupped, thick and rubbery with chlorotic margins. Management of the whitefly vector and TYLCV rests primarily on insecticides and host-free periods, but insecticide resistance is creating the need for TYLCV resistant varieties as an alternative management tool. A replicated variety trial was conducted in spring 2007 at Immokalee, FL with eight potential TYLCV resistant varieties.  Whitefly and disease pressure was heavy with average 9.9 ± 0.38 (mean ± SE) adult whiteflies per leaf and with most susceptible symptomatic plants for TYLCV. Total marketable yields ranged from 58 to 23.9 t/ha among varieties. The highest yielding TYLCV resistant varieties were ‘HA 3078’ (31.3 and 58.0 t/ha) and ‘3074’ or ‘Inbar’ (27.8 and 56.5 t/ha) as compared with the ‘FL 47’ a susceptible variety that yielded 9.2 and 23.9 t/ha extra-large fruit and total marketable yield respectively.  The firmest fruits were ‘Tygress’ and ‘HA 3075’ (‘Ofri’), but ‘Tygress’ had a low color rating.  There were no differences among ‘FL 8580’, ‘HA 3074’ (‘Inbar’) and ‘3075’ (‘Ofri’) than ‘FL 47’ in total unmarketable fruit. Most unmarketable fruit caused by sunscald and yellow shoulder scar due to the reduced foliage.  Thus, the highest yielded TYLCV varieties were ‘HA 3078’ and ‘3074’ (‘Inbar’) for first harvest extra-large, total extra-large and total marketable yield and the low  amount of unmarketable fruits although performance of ‘HA 3075’ (‘Ofri’) and ‘Tygress’ was also satisfactory.