Ripening Dynamics of Divico, a Fungal Disease-Resistant Grape Variety

Climate change and the reduced use of plant-protection products are posing new challenges for viticulture. For the first time, this study provides detailed knowledge on the ripening of Divico and shows that stable quality characteristics can be obtained under varying climatic conditions.

Divico, the most widely cultivated fungal disease-resistant red grape variety in Switzerland, shows resistance to downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator) and grey mould (Botrytis cinerea). Despite the growing importance of this variety, data on the evolution of the grapes over the course of ripening have heretofore been scant.  Consequently, the ripening of Divico was studied, with Pinot noir serving as the basis of comparison for accumulation of sugars and evolution of acidity. In addition, the monitoring of phenolic maturity in Divico revealed similarities with one of its parent varieties, Gamaret.  

Monitoring ripeness over several years in Swiss vineyards

Researchers monitored Divico and Pinot noir over four vintages in Agroscope’s experimental vineyards in Pully and Leytron. Grape samples were taken on a regular basis from veraison up to harvest. Analyses focused on sugar content, acid content and pH.  The ripening curves of the two grape varieties were then compared using statistical models. For Divico, the Total Polyphenol Index (TPI) as well as the anthocyanin concentration were also measured.

Minimal increase in sugars at the end of ripening

Divico achieved ripeness with lower sugar levels than Pinot noir and exhibited a distinct sugar plateau towards the end of ripening, after which sugar concentration remained largely stable. In practice, this could help avoid excessively high alcohol levels. The study also showed that the effect of vintage on timing of ripening was stronger than the effect of crop site.

Stable acidity and pH despite varying climates

One of the main findings concerns the stability of Divico’s acid composition, which allows a relatively constant pH value to be maintained at ripeness. At the end of ripening, pH values were approximately 3.3 at Leytron and 3.1 at Pully, regardless of the vintage. This stability suggests that Divico is capable of producing wines with a certain acidity, even under varying climatic conditions.

High anthocyanin content imparts an intense colour to Divico

Divico berries attained very high concentrations of anthocyanins, the pigments responsible for the red colour of the grapes. Researchers observed a distinct accumulation peak of these compounds over the course of ripening, similar to that observed for Gamaret, one of its parent varieties. In hot, dry years, this maximum was reached earlier. These high pigment levels explain Divico’s potential for producing intensely coloured red wines, and in the future could serve as an indicator for determining the optimal harvest date.