The spatiotemporal spread of esca disease in a Cabernet Sauvignon vineyard: a statistical analysis of field data

The occurrence and spread of plants showing esca symptoms were assessed in a vineyard located on the plains of a northern Italian wine-growing region. Esca disease symptoms were assessed over 16 consecutive years, beginning one year after planting. The number of plants with symptoms was recorded over time, considering both vines with foliar symptoms in the year of assessment (manifest esca) and vines with foliar symptoms in previous years (hidden esca). The sum of manifest and hidden esca was indicated as cumulative esca. The first symptoms of esca appeared in the sixth year of cultivation, with the incidence of manifest esca increasing to approximately 3% nine years after planting. The number of cumulative plants with symptoms increased exponentially in the final period of observation. The aim of this work was to investigate the spatiotemporal spread of esca infection throughout the vineyard and to assess the distribution pattern of plants with symptoms using Bayesian spatiotemporal models. The research results seem to support a higher probability of infection along rows rather than among adjacent rows. This observation may have implications for the technical management of the vineyard.