Grape growers need to control the powdery mildew to produce high-quality wine, without resorting to overkill, but how much powdery mildew is too much?

Mere traces of powdery mildew were found to raise havoc with wine quality. It`s not the small amount of mildew that is the problem, but the spoilage microbes that tag along. They compete with desirable yeasts during fermentation to produce terrible flavors in the finished wine (cow manure, anyone?).

Cornell plant pathologists, entomologists, and enologists collaborated in a 6-year project to untangle just how this occurs, and how to avoid it. Traces of mildew start the problem, and they somehow make the affected grape s more attractive to fruit-feeding insects. The insects injure the berries, and then the rotters arrive. The end result is contamination of the fermentation process, and lousy wine. The trace mildew infections occur about 3 weeks after bloom. Pinpointing this time has allowed them to be efficiently controlled, thereby preserving crop health, and insuring the wine will be of the best possible quality.

Consumers will remember a single bottle of contaminated wine long after they have forgotten several excellent vintages produced by the same winery. If this is their first experience with a particular winery, it is also likely to be their last. Better grapes means better wines, fewer complaints, more repeat sales, and an enhanced reputation for New York Wines.

• Other USDA (e.g., Water Quality, Special Grants, NRI)
• New York Wine and Grape Foundation

• Robert C. Seem
• Wayne F. Wilcox
• Megan M. Kennelly
• Andrea Ficke
• Thomas Henick-Kling
• Lorenza Conterno