Peronospora violacea

Peronospora violacea is a floricolous downy mildew which infects plants in the Caprifoliaceae. It has been reported from hosts in the genera Dipsacus, Knautia, Lomelosia, Scabiosa, and Succisa.^[1]

Peronospora violacea
A flowerhead of Succisa pratensis infected by Peronospora violacea.
Scientific classification
Domain:	Eukaryota
Clade:	Sar
Clade:	Stramenopiles
Clade:	Pseudofungi
Class:	Oomycetes
Order:	Peronosporales
Family:	Peronosporaceae
Genus:	Peronospora
Species:	P. violacea
Binomial name
Peronospora violacea Berkeley, 1860

It produces conidiophores on the petals and styles of the host, oospores inside the petal and style tissue, and suppresses the development of the anthers. Infection is systemic, with hyphae produced in the xylem of the host rhizomes and stems.^[2]

In infected plants of Succisa pratensis the flowers have longer, pinker petals on which the conidophores are produced.^[3] However, other authors report that on the same host it causes the host corollas to be brownish and dead-looking.^[4]

Gallery

• 
  Conidiophores of Peronospora violacea on a petal of Succisa pratensis, viewed under the microscope (focus stacked image).
• 
  Flowerheads of Succisa pratensis, infected (right) and uninfected (left) with Peronospora violacea.
• 
  A flowerhead of Knautia arvensis infected with Peronospora violacea.
• 
  Conidiophores of Peronospora violacea on a petal of Knautia arvensis.