Mildew: /ˈmɪldjuː/ a very small white fungus that grows on walls, plants, food, etc. in warm wet conditions. Moho.
Batch: a number of people or things that are dealt with as a group. Hornada, tanda, lote, pila, montón, grupo. E.g. Each summer a new batch of students tries to find work. He worked his way through the batch of letters on his desk. We deliver the goods in batches.