Phytophthora pseudosyringae
Scientific classification
Domain:	Eukaryota
Clade:	Diaphoretickes
Clade:	SAR
Clade:	Stramenopiles
Phylum:	Oomycota
Order:	Peronosporales
Family:	Peronosporaceae
Genus:	Phytophthora
Species:	P. pseudosyringae
Binomial name
Phytophthora pseudosyringae T. Jung and T.I. Burgess, 2009

Phytophthora pseudosyringae is a semi-papillate homothallic soil-borne plant pathogen causing root and collar rot of broadleaf tree species in Europe.^[1] It is associated with necrotic fine roots and stem necroses of Fagus sylvatica and Alnus glutinosa, and isolates are moderately aggressive to fine roots of oaks and beech (Nothofagus^[2]), highly aggressive to holly leaves and apple fruits, and slightly pathogenic to alder bark. It belongs to the class of oomycetes and is often described as a ‘fungal-like’ organism since they form a heterotrophic mycelium as the ‘true fungi’, but in contrast, their cell wall lacks chitin and is composed only of cellulose and glucans.^{[citation needed]}

Its name derives from Greek Phytophthora φυτόν (phytón), “plant” and φθορά (phthorá), “destruction”; “the plant-destroyer” and plurivora and from Latin (pluri = many, -vora = feeding).^{[citation needed]}