1 A very common disease of fruit caused by fungi of the genus Sclerotinia (usually S. fructigena). Fruits susceptible to it include apples, pears, cherries, plums, etc. Initially, soft brown patches appear on the fruit, often at a site of injury, and these gradually spread until the whole fruit is affected. Fungal conidia are produced from small, pale-coloured, cottony patches which typically appear on the rotting fruit.
2 A type of timber decay in which the wood turns a reddish-brown colour and becomes cracked and eventually crumbly in texture. Fungi that cause brown rots are usually unable to break down the lignin component of wood.