There is a small amount of information dealing with tomato yield and quality losses due to infection by viral species of the bipartite Begomovirus complex occurring in South America. A trial was carried out in order to determine the impact of an early Begomovirus infection on yield and quality parameters using a susceptible processing cultivar. Plants were inoculated for four days under controlled conditions using viruliferous whiteflies (Bemisia tabaci biotype B) 18 days after sowing. Control (non-inoculated) plants were kept in an isolated greenhouse without the presence of the vector. Seedlings of control and inoculated plants were transplanted to the field in the same day. A randomized block design with four replications (10 plants per plot) was used. Sequence analysis of a segment from the viral DNA-A component indicated that the inoculum employed in the present trial was an isolate distinct yet genetically related to Tomato chlorotic mottle virus (one species of the Brazilian Begomovirus complex). A significant yield difference of about 60% was observed between control and infected plants (109.0 t/ha vs. 48.2 t/ha, respectively). The major difference was observed in the number of fruits per plant (an average of 66 fruits on control plants versus 38 fruits on early inoculated plants). No significant difference was observed for average fruit weight and total amount of soluble solids. These results indicate that some simple and useful management strategies such as isolation of seedling production areas and selection of adequate transplanting time could minimize yield losses due to Begomovirus infection. In addition, the results reinforce the epidemiological importance of avoiding precocious plant exposure to potentially viruliferous whiteflies, especially when working with highly susceptible tomato genotypes.
Lycopersicon esculentum; Bemisia tabaci biotype B; whitefly; geminivirus
