Phytophthora rosacearum

Name and publication

Phytophthora rosacearum Hansen & Wilcox (2009)

Hansen EM, Wilcox WF, Reeser PW, and Sutton W. 2009. Phytophthora rosacearum and P. sansomeana, new species segregated from the Phytophthora megasperma "complex". Mycologia 101: 129–135.

Corresponding author:


from Hansen et al. (2009)




derived from Rosaceae, the family of fruit trees most frequently parasitized by this pathogen


Type: UNITED STATES OF AMERICA, from California, collected from apple by John Mircetich as isolate 20-3-9; holotype, OSU52, in Herbarium OSC (dried culture)

Ex-type: ATCC MYA-4456

Sequences for ex-type in original manuscript: isolate 52: ITSrDNA EU925376

Ex-type in other collections

ATCC MYA-4456 = CBS 124696, P3112 (WPC), CPHST BL 53 (Abad), isolate 52, Maxwell #174, P462 Brazier et al 2003, P3112 Forster et al. 2000, 47J1 (Yang)

Molecular identification

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

Phytophthora rosacearum isolate 52 ITS rDNA EU925376

Phytophthora rosacearum isolate CPHST BL 53 (= P3112) COI MH477758

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

Clade 6a

Morphological identification

adapted from Hansen et al. (2009)

Colonies and cardinal temperatures

Colony morphology on PDA, V8, and MEA with non-distinct pattern. Minimum growth temperature 3°C, optimum 27°C, and maximum 33°C.

Conditions for growth and sporulation

Sporangia and hyphal swellings produced on plugs of culture media flooded in soil extract.

Asexual phase

Sporangia nonpapillate; persistent; ovoid, ellipsoid, obturbinate (46–79 L x 26–48 W µm), some constricted and some with tapered base; showing simple and extended internal proliferation; originated in unbranched sporangiophores. Hyphal swellings globose, subglobose, sometimes with radiating hyphae, sometimes catenulate. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia smooth-walled, globose (19–40 µm diam); antheridia paragynous, spherical, ovoid, club-shaped with abundant knotted hyphae; oospores plerotic, aplerotic, and slightly aplerotic (18–33 µm diam). Many aborted oospores and showing thick wall.

Most typical characters

Phytophthora rosacearum is characterized by the sporangia shape and proliferation and the morphological characters of the antheridia

Additional specimen(s) evaluated

Phytophthora rosacearum ex-type CPHST BL 53, duplicate of P3112 World Phytophthora Collection)

Hosts and distribution

Distribution: North America (CA, OH, MD, NY)
Substrate: fruit
Disease note: pathogenic
Host: Malus domestica, Prunus spp. (Rosaceae)

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

Additional info:
Substrate: rhizosphere

Additional references and links

Fact sheet author

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