Noble rot fungus (Botrytis cinerea) growing on grapes. Under the right conditions this mould is beneficial to the wine-making process. It causes the grapes to shrivel, which concentrates and intensifies their sugars and flavour. It also keeps the acid levels in the fruit high, preventing the resulting wine from being too sweet. These are Muscadelle grapes that will be used to make the dessert wine Montbazillac.