Viticultural and oenological strategies to prevent quality losses due to Botrytis cinerea

The loss of quality and economic damage caused by the infestation of grapes with Botrytis cinerea, the pathogen that causes grey rot, extends across the entire wine production value chain. Botrytis-associated problems include the appearance of musty off-flavors, poor filterability, high color up to brown coloration and, in the worst case, the total loss of the harvest or vintage. The occurrence of Botrytis infections is highly dependent on the weather and is therefore subject to strong vintage fluctuations. Due to the increasing occurrence of extreme weather events and favored by climate change, more aggressive Botrytis cinerea strainsare now also occurring more frequently. Common strategies against Botrytis infections to date have been the use of fungicides and viticultural measures such as defoliation of the vines. The costs for botryticide applications are high at 220 €/ha and the labor costs for defoliation are also considerable. If timed incorrectly, such measures can also cause sunburn damage, which results in further economic losses.

The aim of the research project is to largely eliminate the quality losses caused by Botrytis cinerea infections of grapes, which result from color changes, the development of undesirable fungal notes and the loss of varietal aroma. For this purpose, a molecular biological diagnostic method for Botrytis cinerea strains from the vineyard is to be developed and established, with which they can be classified into low-, medium- and high-activity classes based on their laccase secretion. The effectiveness of oenological treatment methods, such as the use of activated carbon, tannins and flash pasteurization, will be evaluated in a differentiated manner for these three classes and validated in practice. Based on the results obtained and chemical and sensory analyses of the wines produced, recommendations for the wine industry will be drawn up.

The cooperation project with the Institute of Viticulture and Enology (Dr. Pascal-Wegmann-Herr) and the University of Bonn (project management Dr. Fabian Weber) is funded by the German Federal Ministry of Economics and Climate Protection via AiF (Forschungskreis der Ernährungsindustrie e.V. (FEI)) Project number: AiF 21630 N