Botritis is a fungus which affects grapes of the species Vitis vinifera, the European wine grape. It infects the grape clusters and inserts its hyphae into the grapes themselves. In large amounts, it will dehydrate the grapes completely and make them worthless. In small amounts, it can actually strengthen the flavor of the grapes by increasing their sugar content, making for better wine. There has been little to no success with either introducing or removing this fungus in the vineyard, although sometimes it can be added to grapes after they are already picked.

since this fungus can be beneficial, it is sometimes known as noble rot.