''Peronospora arborescens'' is a plant pathogen. It causes downy mildew on leaves of ''

Papaver ''Papaver'' is a genus of 70–100 species of frost-tolerant annual plant, annuals, biennial plant, biennials, and perennial plant, perennials native plant, native to temperateness, temperate and cold regions of Eurasia, Africa and North America ...

'' spp. It has economic importance on ''

Papaver somniferum ''Papaver somniferum'', commonly known as the opium poppy or breadseed poppy, is a species of flowering plant in the family Papaveraceae. It is the species of plant from which both opium and poppy seeds are derived and is also a valuable orname ...

'' grown as an oilseed crop, for example in central and eastern Europe. It is controlled by sanitation,

crop rotation Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the pro ...

, use of clean seed and fungicide sprays of the foliage. There are other species of ''Peronospora'' which occur on ''Papaver'': ''Peronospora argemones'' ( Gäum.), ''Peronospora cristata'' ( Tranzschel), and ''Peronospora papaveris-pilosi'' (Vienn.-Bourg.).

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Further reading