one rotten apple spoils the whole barrel
1the rotten apple injures its neighbour — The proverb is also found in a number of variant forms, some of which are illustrated below. Cf. L. pomum compunctum cito corrumpit sibi junctum, a rotten apple quickly infects its neighbour. 1340 Ayenbite of Inwit (EETS) 205 A roted eppel amang… …
