| peronospora | (n) genus of destructive downy mildews, Syn. genus Peronospora |
| peronosporaceae | (n) parasitic fungi: downy mildews, Syn. family Peronosporaceae |
| peronosporales | (n) order of chiefly parasitic lower fungi: Albuginaceae and Peronosporaceae and Pythiaceae, Syn. order Peronosporales |
| blue mold fungus | (n) fungus causing a serious disease in tobacco plants characterized by bluish-grey mildew on undersides of leaves, Syn. Peronospora tabacina |
| onion mildew | (n) fungus causing a downy mildew on onions, Syn. Peronospora destructor |
| tobacco mildew | (n) fungus causing a downy mildew on growing tobacco, Syn. Peronospora hyoscyami |
| Peronospora | prop. n. A genus of destructive downy mildews. |
| Peronosporaceae | prop. n. A natural family of parasitic fungi; the downy mildews. |
| Peronosporales | prop. n. An order of chiefly parasitic lower fungi, including the |