There is a growing list of grape, must and wine associated yeast that can play an important role in the perceived quality of finished wine. As some wineries rely on resident yeast species to conduct the primary fermentation, more non-Saccharomyces yeast are becoming sporadically problematic. Careful observation and environmental management of these fermentations are necessary in order to prevent unwanted attributes arising. Understanding the ecology of these yeast are a necessary prerequisite in encouraging the beneficial, managing the benign, discouraging the unwanted and eliminating the spoilage growth of winery associated yeast.
See The Diversity of Wine Yeasts for a more indepth discussion of the yeast ecology associated with a wine fermentation.