- Fruits: grapes
- Sustainable Communities: sustainability measures
Powdery mildew (PM) is a common disease affecting grapevines, particularly in the northeastern region of the United States. The most common fungicide for control of this disease, elemental sulfur (S-0), is preferred due to its low cost, efficacy, and environmental sustainability. However, S-0 has been shown to result in hydrogen sulfide (H2S) “rotten egg” aroma formation during winemaking, and my recent work has shown that this formation can continue in the wine bottle. These consequences discourage the use of S-0 against PM and grape growers instead rely on less environmentally and economically sustainable PM fungicides close to harvest. Current recommendations for sulfur spray limits at harvest are based upon the amount of S-0 necessary for increasing H2S production during fermentation. However, a more useful limit would be based on the amount of residue necessary to form H2S during storage, as this is more challenging to remove from wine. The objective of my research is to define appropriate limits for sulfur spray residues that avoid formation of H2S during storage. The outcome of this work will be to allow both winemakers and grape-growers to define appropriate limits for the use of sulfur sprays for PM control, and minimize the use of less sustainable alternative fungicides. Additionally, this work will identify the intermediate, wine-soluble compounds formed from S-0 that are responsible for re-emergence of H2S. This will lead to development of prophylactic treatment for wines produced from grapes with excess sulfur residues, which will incentivize the use of S-0 in place of other PM controls.
Project objectives from proposal:
- Define new limits for use of S-0 fungicides based upon H2S during storage instead of H2S formed during fermentation.
- Identify the wine-soluble precursor compounds responsible for H2S formation during storage.