blue mold fungus blue·mold·fun·gus uncommon noun 1. fungus causing a serious disease in tobacco plants characterized by bluish-gray mildew on undersides of leaves Synonymsblue mold fungusPeronospora tabacina Related words Broader terms downy mildew Parts Peronospora WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
