Tomato production under mesh reduces crop loss to tomato spotted wilt virus in some cultivars

Seedlings of three tomato (Lycopersicon esculentum Mill.) cultivars ['RDD', carrier of the Sw5 gene, which confers resistance to tomato spotted wilt v irus (TSWV); 'Pitihue', 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 x 10 t hreads/cm, Systemic symptoms and number of dead plants were recorded and en zymelinked immunosorbent assays (ELISA) were performed,'Rutgers' exhibited severe systemic symptoms regardless of treatment and a high number of plant s died. The level of infected plants remained low when protective measures were applied to seedlings of 'Pitihue' 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 cultivati on did not reduce yield. Although the percentage of infected plants was hig her when cultivated under mesh, the yield of all three cultivars was greate r than in the open field, The environment created under mesh stimulated gro wth, neutralizing the effect of the infection.