Phytophthora pseudosyringae

Name and publication

Phytophthora pseudosyringae Jung & Delatour (2003)

Jung T, Nechwatal J, Cooke DE, Hartmann G, Blaschke M, Osswald WF, Duncan JM, and Delatour C. 2003. Phytophthora pseudosyringae sp. nov., a new species causing root and collar rot of deciduous tree species in Europe. Mycological Research 107: 772–789.

Correponding author:


from Jung et al. (2003)




refers to morphological and physiological similarities to Phytophthora syringae that have led to misidentifications in the past


Type: GERMANY, isolated from rhizosphere of Quercus robur in Bavaria, Gerolzhofen, during November 1997 by T. Jung, IFB-GeroR7

Ex-type: CBS 111772 and IFB-PSEU 6 (living cultures)

Sequences for ex-type in original manuscript: ITSrDNA: AY230190 (PSEU 6)

Ex-type in other collections

CBS 111772 = P10437 (WOC/WPC), PD 07 03486595, CPHST BL 51G (Abad), 30A8 (Yang)

Molecular identification

Voucher sequences for barcoding genes (ITS rDNA and COI) of the ex-type (see Molecular protocols page)

Phytophthora pseudosyringae isolate CPHST BL 51G (= P10437 WPC) = ITS rDNA MG865574, COI MH136966

Sequences for ex-type in other sources
Position in ITS phylogenetic tree

Clade 3a

Morphological identification

adapted from Jung et al. (2003)

Colonies and cardinal temperatures

Colony morphology on PDA, V8A, MEA with rosette chrysanthemum pattern. Minimum growth temperature 5°C, optimum 20°C, and maximum 25°C.

Conditions for growth and sporulation

Hyphal swellings formed in soil water extract. Oogonia readily produced in culture media. 

Asexual phase

Sporangia semipapillate; persistent but sometimes caducous with short and medium pedicels (2–20 µm); limoniform, ellipsoid, ovoid, obpyriform, or irregular shapes (20–95 L x 18–45 W µm) and sometimes with elongated necks and with constrictions; no internal proliferation is observed, sporangia originated individual or in simple sympodial and clustered sporangiophores. Hyphal swellings globose, subglobose, elongate formed in catenulated arrangement. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia smooth-walled; spherical to slightly globose (20–37 µm diam) sometimes with tapered bases; antheridia paragynous, spherical, club-shaped, or irregular shape, sometimes showing digitate projections and knotted hyphae; oospores plerotic, aplerotic, and slightly aplerotic (17–31 µm diam).

Most typical characters

Phytophthora pseudosyringae is characterized by the presence of sporangia semipapillate, persistent but sometimes caducous with short and medium pedicels, and the shape of the hyphal swellings.

Additional specimen(s) evaluated

Phytophthora pseudosyringae ex-type CPHST BL 51G, duplicate of P10437 (World Phytophthora Collection) 

Hosts and distribution

Distribution: Europe, North America, South America (Chile)
Substrate: soil, roots; also fruits when inoculated
Disease note: root and collar rot; a moderately aggressive pathogen of various Quercus spp. (Jung et al. 2003); also causing a fruit rot of apple and leaf rot of Ilex aquifolium when inoculated
Host: Quercus spp., Fagus sylvatica, Alnus glutinosa, and other hardwood species

Retrieved February 01, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

Fact sheet author

Z. Gloria Abad, Ph.D., USDA-APHIS-PPQ-S&T Beltsville Laboratory, United States of America