In Franconia, the northern part of Bavaria in Germany, climate change, visible in earlier bud break, advanced flowering and earlier grape maturity, leads to a decrease of traditionally cultivated early ripening aromatic white wine varieties as Mueller-Thurgau (30 % of the wine growing area) and Bacchus (12 %). With the predicted rise of temperature in all European wine regions the conditions for white wine grape varieties will decline and the grapes themselves will lose a part of their aromatic and fruity expression. Variety change towards the cultivation of later ripening white wine varieties is a very expensive and long-term process, and must be accompanied by special marketing efforts.
In the “cool climate” region Franconia, adapted methods are required for the longer use of traditionally grown aromatic early ripening varieties. Studies about maturity management of the early ripening variety Mueller-Thurgau show first results. Cordon pruning compared with traditional spur pruned training system, leads in dependence of botrytis infection to a maturity delay of 4 up to 6 days. The new natural growth training system, also called “minimal pruning”, results in a maturity delay of 8 up to 12 days in the same varieties.
Later grape harvest times economize energy for must cooling and fermentation control. Lower night temperatures can better conserve the fresh and fruity flavours of these aromatic grapes. The consequences of maturity retardation effects on must and wine quality will be studied.
Authors: Arnold Schwab, Ulrike Maaß
Bavarian State Institute for Viticulture and Horticulture, An der Steige 15, D-97332 Veitshöchheim
Keywords: Climate change, Franconia, earlier harvest time, variety change, canopy management