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Poster: Epidemiology: Pathogen Dispersal


Spatial dynamics of a begomovirus disease in processing tomato in central Brazil
A. BERGAMIN FILHO (1), A. Bergamin Filho (1) (1) University of Sao Paulo, Brazil

The begomovirus disease is one of the most important viral diseases in the tomato crop in Brazil. The objective of this work was to study the spatial aggregation of begomovirus disease in two central-pivot irrigated areas for processing tomatoes in central Brazil. A total of 24 plots (15x15 plants) was weekly evaluated by visual inspection for identification of begomovirus symptomatic plants (BSP). The spatial distribution of the disease was analyzed by: binominal index of dispersion, Taylor’s power law, and ordinary run. Tomato severe rugose virus was the predominant begomovirus species in tomato. It was also detected in a few non-tomato plants. The apatial pattern of sumptomatic plants was slightly aggregated. A relevant difference was observed between plots located at the center (PC) and at the edge (PE) of the pivots. The distribution of BSP in PC was more aggregated than in PE. It is most likely that at PE the primary spread is the major component of virus epidemics in the field. These results suggest that the distribution of BSP in PC and PE is ruled out by at least three different dissemination mechanisms: a random (primary spread), and two aggregation components, a real secondary spread, and a “false” secondary spread. However, it is clear that the primary spread is the most important component in begomovirus epidemics. Hence, management of begomovirus diseases focusing only on the target fields is certainly not enough for an efficient control.