mil·dew 
(mĭld′, -dy′)
(mĭld′, -dy′)n.
1.
a. Any of various fungi or oomycetes that form a superficial, usually whitish growth on plants and various organic materials.
b. A plant disease caused by such organisms.
2. A superficial coating or discoloration of organic materials, such as cloth, paper, or leather, caused by fungi, especially under damp conditions.
tr. & intr.v. mil·dewed, mil·dew·ing, mil·dews
To affect or become affected with mildew.
[Middle English mildeu, from Old English mildēaw, honeydew, nectar; see melit- in the Appendix of Indo-European roots.]
mildew′y adj.