From 1998 to 2001 three vineyards in the three areas Arganda, San Martin de Valdeiglesias and
Navalcarnero, included in the vine-growing region “Wines of Madrid”, were surveyed for esca incidence and spatial
distribution of infected vines. Individual vines were recorded as “diseased” when they showed esca symptoms, both in
summer surveys (symptoms on leaves, weak growth, short branches growth) and in winter surveys (necrosis of trunk
and main branches). Data recorded over several years in the same vineyard and data from different vineyards in the
same year were compared in order to study disease spread and possible primary sources of infection. Our results
showed that: i) esca foliar symptoms were discontinuous from year to year; ii) the distribution of infected vines in the
vineyard was random and, iii) the disease was not spread between adjacent vines