Good news - Esca has no effect on wine quality

hat can you do with grapes from vines affected by Esca? Should they be cut before the harvest or can they be incorporated into the crop? Should they be used for a winery’s first, second or third wine? To get some answers to these questions, twelve properties on Bordeaux’s Left Bank made their most contaminated blocks available to Vitinnov and Bordeaux Sciences Agro for 10 years.

“We did small-batch winemaking on five plots over two vintages,” said Coralie Dewasme, an engineer at Bordeaux Sciences Agro, on 28 January. The researchers discarded green, pink and shrivelled grapes. First they confirmed that grapes from vines showing Esca symptoms ripen slower. “We also saw an impact on phenolic ripeness, with a slight drop in anthocyanin levels, but no difference in total tannins”, added Dewasme.

Experts tasted the wines the year after the harvest, then two and six years after the harvest. “They often judged the wines from the affected vines to have less colour and less length on the palate”. However, the occurrence or not of Esca had no impact on the overall assessment of the wines. “In some flights, the wines from the diseased vines were even rated the highest”, commented Dewasme.

Although this is good news, Esca nevertheless has an impact on crop size. “Our evaluations on 8 blocks over 5 vintages showed an overall 35% decrease in yield on affected vines compared to healthy vines”, said Dewasme. Yields even fell by 55% when the vines showed symptoms for the second year running.