Mildew
a morbid appearance produced on plants by the ravages of parasitical fungi or other cause, or the parasitical fungus itself which produces the morbid appearance. Such fungi are always minute, and sometimes microscopic. Some attack plants internally, and then force their way to the surface. Other mildews are produced by fungi which grow on the surface of plants, as on cabbages, roses, and hops. These fungi, growing on the surface of leaves, fruits, etc., do not establish themselves till the plant on which they grow has become unhealthy from other causes. ab-