(1824) Peronospora farinosa is a species name that has been widely applied to downy mildew on leaves of wild and cultivated Amaranthaceae: Amaranthus, Atriplex, Bassia, Beta, Chenopodium, Halimione, Salsola, Spinacia, etc.

In the past, some of the species on important crop plants have been given names as formae speciales,[1] notably f.sp.

However, phylogentic reconstructions have revealed that these "forms" of Peronospora on different genera and their subdivisions, are distinct species,[2] most of which already have previously published scientific names[3] (see Index Fungorum).

[5] Downy mildew has more direct importance on spinach (Spinacia oleracea),[4] since it affects the harvested part (leaves).

If rotating crops and removing individual infected plants fails, fungicide treatments are effective, and resistant cultivars are available.