Blue mold

Blue mold is a downy mildew disease of tobacco that is caused by Peronospora tabacina, a fungus-like protist in the family Peronosporaceae. Blue mold can cause severe damage to susceptible tobacco plants in many parts of the world. Since it is an obligate parasite, it must have living tobacco tissue in order to grow.

Although tobacco remains the primary host for this disease, other hosts including pepper plants and eggplants can also be reservoirs.