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Nowadays, Tomato spotted wilt virus (TSWV) is one of the most limiting factors for tomato culture in Spain. Some breeding programs have been recently developed to obtain cultivars with resistance to TSWV. The evaluation of six lines of processing tomato obtained from one of these breeding programs and carrying the Sw-5 gene that confers resistance to TSWV, has shown that all these lines have both agronomic (yield, vigor, etc.) and quality characters better or similar to those of control cultivars. The lines tested here could be very useful in regions where TSWV is an endemic disease and to get hybrids that would express heterosis and more stability in different environmental conditions.

Seedlings of three tomato (Lycopersicon esculentum Mill.) cultivars [`RDD', carrier of the Sw5 gene, which confers resistance to tomato spotted wilt virus (TSWV); `Pitihué', tolerant to the virus; and the susceptible cultivar Rutgers] were placed at the four- to five-leaf stage in cages containing a population of viruliferous thrips (Frankliniella occidentalis Perg.), and remained there for 0, 7, or 15 days. Plants were subsequently transplanted either into the open field or in tunnels protected with a mesh of 14 × 10 threads/cm. Systemic symptoms and number of dead plants were recorded and enzymelinked immunosorbent assays (ELISA) were performed. `Rutgers' exhibited severe systemic symptoms regardless of treatment and a high number of plants died. The level of infected plants remained low when protective measures were applied to seedlings of `Pitihué' and acceptable yields were obtained. In open air cultivation, where seedling infection was severe, <20% of `RDD' plants became infected and high yields were obtained; protected cultivation did not reduce yield. Although the percentage of infected plants was higher when cultivated under mesh, the yield of all three cultivars was greater than in the open field. The environment created under mesh stimulated growth, neutralizing the effect of the infection.

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