After the hot summer, it is not easy for wineries to meet the demand for dry and light white wines. Despite the early start of the harvest, the grapes often have a high sugar content, which easily leads to elevated alcohol levels in the cask. And they contain less acid than in cool years. Some winegrowers therefore rely on historical grape varieties, which often ripen much later than classic varieties such as Riesling or Pinot Gris.
"For us, the Yellow Orleans is the answer to climate change," says the Nierstein winemaker Gina Gehring, looking at the large green-yellow grapes in her vineyard in the Niersteiner Roter Hang, whose wines are characterized by the mineral notes of the reddish shimmering slate. "Last year we really struggled to get it ripe because it was so cold. But this year everything is coming together for the Orleans Yellow."
Significant advantages for later ripening grape varieties
At the Institute for Vine Breeding at the Geisenheim University in the Rheingau, towards the end of the first week of September, 83 degrees Oechsle were measured for the Riesling, which is the measure of the sugar content of the grapes, but only 54 for the Yellow Orleans. In past centuries it was only found in a few places such as the Roter Hang or the Rüdesheimer Berg are given the opportunity to ripen Yellow Orleans with sufficient sunshine and the right slope, explains Institute Director Joachim Schmid. "We've been spoiled by higher temperatures since 1988, but now we're more concerned." Therefore, there are now clear advantages for later-ripening historical grape varieties.
The winemaker Martin Koch in Hahnheim (Mainz-Bingen district) appreciates the Yellow Orleans as a connection to the Cistercian monks who brought this grape variety from France to the Rhine in the Middle Ages. "It is very attractive for us to plant these vines again in the same location as the Cistercians - because of these monks we are also called Abthof", explains the Rhine-Hessian winemaker. It is understandable that the Yellow Orleans was no longer cultivated at a time when temperatures were cooler. "But today that's just an advantage."
In addition to the Yellow Orleans, Heunisch wine is now also being grown and bottled - this was a widespread type of white wine in Central Europe up to the mid-19th century. "But we have also discovered a wealth of other historical grape varieties that are better suited to warmer climates than classic grape varieties," says the vine refiner Ulrich Martin from Gundheim (Alzey-Worms district). One of his favorites is Grüner Adelfränkisch - "this grape variety only really feels at home at 40 degrees". With rising temperatures, the problem with Riesling and Chardonnay is that the acid is disappearing. "Green Adelfränkisch retains its acidity and is a climate winner."
Breeding of new grape varieties is by no means complete
Until 2007, this grape variety, which probably originally came from Moravia and was related to the Traminer, was considered extinct. "It is very important to preserve the genetic resources of historical grape varieties," says scientist Schmid. "We have to store the complete range in some form - preferably in the field", i.e. in commercial cultivation. The care of historical grape varieties alone in scientific facilities offers no guarantee for their continued existence.
From his point of view, the preservation of a gene pool that is as comprehensive as possible makes sense because the breeding of new grape varieties with a view to changing requirements is by no means complete. So far, the focus has been on the Piwis, fungus-resistant grape varieties that are less susceptible to fungal diseases and therefore place fewer demands on plant protection. "But many Piwis are ripe relatively early," says Schmid. "Crossbreeding with historical grape varieties makes perfect sense."
"I love Riesling more than anything," says Gina Gehring. "But of course you have to think about how things will continue in the future." In order to achieve the highest possible quality, she cuts some green grapes from the Yellow Orleans in summer. This also helps the vines to better cope with the drought. She uses the unripe grapes to make verjuice, a sour juice with no additives or preservatives. "We use it like pure lemons," says the 24-year-old young winemaker. In the winery, verjus is valued as a non-alcoholic spritzer, and used in upscale gastronomy for salad dressings. "And you can use verjuice for cocktails - it's super hip in Berlin."