Botrytis goes by another name: Noble Rot. We should get it out of the way that Botrytis Cinerea is a rot that does infect the grapes. Sounds terrible but it is a wonderous rot that winemakers crave for. Botrytis will suck out the water content of the grapes and leave only the sugars left. Not only this but they will also contribute flavours that are found in the resulting wines as dried apricots, candied lemon, orange marmalade, baking spices, raisins and cinnamon.
Botrytis will only infect grapes that have been covered in a layer of mist in the morning, followed by sunshine in the afternoon, repeated over and over. The more repetition of this process the more likely Botrytis will infect and spread throughout the grape bunches. This is fantastic for winemakers that want to produce a sweet wine, not so much for those that don’t and get stuck with it. Botrytis generally won’t occur on the grape bunches until later on into the harvest so the fair majority of grapes will have already been picked not making that so much of an issue.
Botrytis is behind the leading sweet wines in the world. The famed wines of Sauternes in France, Tokaji in Hungary and the Beerenauslese and Trockenbeerenauslese of Germany and Austria. Most sweet wines produced across the new world of wine will be made in this style as well. There are fantastic examples of Botrytis wines produced across the USA, Australia, South Africa and New Zealand.