The Secret Power of Noble Rot

Early morning mists in Sauternes are key to the development of noble rot Let us now praise noble rot.

My colleague Toby Morrhall, currently doing a brilliant job securing our Burgundies and the cream of South American wine for The Society, once told me that the greatest wine of all was Sauternes. He has a point.

What an achievement to make glorious nectar, capable of living 50 to 100 years, from grapes that look rotten on the vine. Though many claim the discovery from Schloss Johannisberg to Tokay to Yquem, nobody knows who first discovered the secret power of noble rot. The story usually involves an absent landlord returning late to authorise his vineyard workers to pick. When all looked lost, they were told to pick anyway and found they made fabulous sweet wine.

Rot on grapes comes in several guises. We shun grey mould that spoils the fruit and sick rot that turns wine into vinegar. Noble rot, however, botrytis cinerea/pourriture noble/Edelfaule/muffa nobile concentrates all the good elements of the grape like sugar and fruit acidity while removing over half the grape’s water content.

The skin of the grapes must be undamaged and ideal conditions occur in a temperate climate in which humidity associated with early morning mists followed by warm, sunny afternoons favours development of the fungus. The different temperature of rivers, Garonne and Ciron in Sauternes and the Tisza and Bodrog in Tokay encourage these mists. Dry hot conditions may ‘raisin’ the grapes but do not allow the fungus to develop.

Botrytis cinerea spreads unpredicatably and sometimes rapidly, so you need to send your skilled pickers into the vineyard several times, sometimes over an extended period to harvest. Because of the water loss and caprices of the weather, yields can be ridiculously small, often less than a fifth or even less of normal production. One vine may produce only one glass of wine. It is precious and worth savouring.


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