Botrytis cinerea
Botrytis cinerea is a fungal pathogen affecting grapevines, best known for its dual role in viticulture as both a destructive agent of grey rot and a beneficial agent in the form of noble rot (French: pourriture noble), which is essential for the production of many of the world’s most celebrated sweet wines.[1]
Background
Botrytis cinerea is a necrotrophic fungus that infects over 200 plant species, including grapes. Its impact on viticulture has been documented since antiquity, with evidence suggesting its role in early sweet wine traditions.[2] The fungus thrives in humid conditions, with infection typically beginning in damaged or overripe grapes.
Grey Rot
Under damp or uncontrolled conditions, Botrytis develops as grey rot, rapidly spreading through bunches and destroying fruit quality.[3] The infection causes browning, off-flavours, and reduced yields, making it one of the most feared grapevine diseases. Vineyard practices such as canopy management, well-timed fungicide use, and careful harvest decisions are critical to prevention.
Noble Rot
When specific climatic conditions occur—typically morning humidity followed by warm, dry afternoons—the fungus dehydrates grapes slowly, concentrating sugars, acids, and flavour precursors. This phenomenon, called noble rot, is fundamental to wines such as Sauternes, Tokaji, Trockenbeerenauslese, and certain Austrian sweet wines.[4] Noble rot alters grape chemistry by increasing glycerol and flavour complexity while reducing acidity, giving the resulting wines their unique texture and aromatic profile.[5]
Role in Winemaking
The influence of Botrytis on winemaking depends entirely on whether conditions favour grey rot or noble rot. Winemakers working with botrytised grapes face challenges including reduced juice yield, long fermentations due to high sugar concentrations, and the need for meticulous grape selection.[6] Despite these difficulties, the wines produced are among the most long-lived and highly valued in the world.
See also
References
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015.
- ↑ McGovern, Ancient Wine: The Search for the Origins of Viniculture, Princeton University Press, 2003.
- ↑ Jackson, Wine Science: Principles and Applications, Academic Press, 2020.
- ↑ OIV, “Botrytis cinerea and noble rot”, oiv.int.
- ↑ Ribéreau-Gayon, Dubourdieu, Donèche & Lonvaud, Handbook of Enology, Wiley, 2006.
- ↑ Robinson (ed.), The Oxford Companion to Wine, 2015.