Viticultural and enological strategies for the prevention of Botrytis cinerea- induced quality losses

Abstract

Infection of the grapes with Botrytis cinerea has a tremendous impact on the resulting crop yield and quality. Well-known problems that are associated with B. cinerea are specific off-flavors, poor filterability, and brownish color in white wines. The development of a B. cinerea infection strongly depends on weather conditions and is highly variable through different vintages. Typical control measures include defoliation and the use of fungicides, which involves high personnel and material costs. They also involve a great risk, especially since the effectiveness and time point of these treatments are difficult to predict. The frequency and severity of B. cinerea infections in Germany will increase due to climate change-induced alteration of weather conditions and the rise of new pathogen strains. In warmer, drier years, heavy Botrytis infection has already been observed, indicating the development of more aggressive strains. Common practices to deal with the negative effects of Botrytis on wine quality have been demonstrated to be ineffective and need to be reconsidered. To approach this problem, first experiments investigating oenological usage of coal and tannins in Botrytis infested must have been conducted. Sensory analysis and CATA confirmed, that common practices are not sufficient enough to battle Botrytis induced off-flavors. According to our results no clear positive effect of tannin treatment could be observed. To obtain more insight into the diversity of Botrytis strains, a PCR fingerprinting method is going to be established, as well as a qPCR method for biomass detection in to obtain more knowledge about climate based developments of B. cinerea. A method for detecting Botrytis induced aroma compounds like Geosmine and 1- Octen- 3-ol, was optimized by using a new CG-MS method. First results show success in validating different strains as well as detecting different aroma compounds in GC-MS.