blue mould
noun
Also called: green mould any fungus of the genus Penicillium that forms a bluish mass on decaying food, leather, etc
any fungal disease of fruit trees characterized by necrosis and a bluish growth on the affected tissue: mostly caused by Penicillium species
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Examples from the Web for blue mould
Historical Examples of blue mould
They kept him in a dark place, like a cheese, until he had the full Tellson flavour and blue-mould upon him.
A Tale of Two CitiesCharles Dickens