Noble rot is a good form of a grey fungus, Botrytis cinerea, affecting wine grapes. For this to happen, grapes must be in warm and humid conditions, usually around 20 °C (68 °F) and above 80% humidity. If the weather stays wet, the rot starts to ruin the wine by stopping the fermentation process and changing the taste, aroma, and appearance of the final wine. Grapes usually become infected with cinerea when they are ripe. If they are then exposed to drier conditions and become partially raisined, this form of infection is known as noble rot. Grapes picked at a specific point can make fine and concentrated sweet wine. Wines produced by this method are known as botrytized wines.
