Spatial Distribution of Esca Symptomatic Plants in Dão Vineyards (Centre Portugal) and Isolation of Associated Fungi

Abstract

During three years, from 2002 to 2004, a vineyard was surveyed for esca incidence and spatial distribution of deceased/symptomatic vines. Individual plants were recorded as diseased when characteristic esca symptoms were visible in summer surveys or in winter surveys. Some of the symptomatic vines were uprooted every year and fungi most commonly isolated from those plants were listed. Two dimensional maps referring the presence/absence of diseased plants were drawn every year and a cumulative map was obtained on the last year of the survey. Based on the former map, spatial distribution of esca symptomatic plants was analysed in order to confirm the null hypothesis of randomness on the disease spread. Our results showed that: i) internal lesions of uprooted vines were classifiable in two main categories, according to the observed decays; ii) with the exception of Eutypa lata, fungi commonly associated with esca were present in the uprooted vines; iii) the number of esca symptomatic plants increased every year of the survey; iv) esca foliar symptoms were discontinuous from year to year and v) the distribution of infected vines on the plot was random.