Abstract
The present study examined the effect on quality caused by esca in both grape clusters and wines. In the
last year (2000) of an eight-year survey of esca foliar symptoms, the vines of two cv. Trebbiano d’Abruzzo vineyards
fell at the moment of grape clusters sampling, into 3 groups: 1. vines with esca symptoms; 2. vines that happened to
be asymptomatic but that were known to be diseased because they had show leaf symptoms in at least one other
survey year and 3. healthy vines. In a third vineyard, in the same growing area, grape clusters were sampled from
vines with trunk renewal that had been restored and from unrenewed vines that had never shown esca leaf symptoms
and were consequently presumed to be healthy. Preliminary results on grape clusters in the first two vineyards
showed differences in composition between symptomatic vines on the one hand, and asymptomatic/diseased vines
and healthy vines on the other, with symptomatic vines having lower levels of reducing sugars and a higher nitrogen
concentration. As a result the alcohol content of wines from symptomatic vines was about 1% v:v lower than that of
wines from the other two groups of vines. Grape clusters and wines from diseased/asymptomatic vines and healthy
vines did not differ in the compositional parameters used in the test except for total polyphenols which gave contrasting
data among the first two vineyards. In grape clusters and wines from the third vineyard the preliminary results
likewise revealed no difference between vines with trunk renewal and unrenewed healthy vines. This finding would
seem to corroborate the practice of trunk renewal as a means of restoring both vines and the quality of grape clusters.
Research is continuing to evaluate the reliability of these results.
