The Collaborative International Dictionary of English v.0.48:

Mildew \Mil"dew\, v. t. [imp. & p. p. Mildewed; p. pr. & vb.
   n. Mildewing.]
   To taint with mildew; as, mildewed clothing.
   [1913 Webster]

         He . . . mildews the white wheat.        --Shak.
   [1913 Webster]