Phytophthora sansomeana

Name and publication

Phytophthora sansomeana Hansen & Reeser (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)




The name commemorates Dr Eva Sansome, whose astute cytological observations established the diploid nature of Phytophthora and other oomycetes.


Type: UNITED STATES OF AMERICA, collected from soybean in Indiana by Reeser, isolate OSU 1819B holotype in Herbarium OSC (dried culture)

Ex-type: ATCC MYA-4455

Sequences for ex-type in original manuscript: OSU 1819B = ITS rDNA EU925375

Ex-type in other collections

MYA-4455 (= 1819B) = P8051 (WOC/WPC), CPHST BL 55 (Abad), CBS 117693, 47H3 (Hong)

Molecular identification

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

Phytophthora sansomeana isolate CPHST BL 55 (= P8051 WPC) = ITS rDNA MG865585, COI MH136977

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

Clade 8a

Morphological identification

adapted from Hansen et al. (2009)

Colonies and cardinal temperatures

Colony after 7 days of growth on potato dextrose agar, malt extract agar with slight chrysanthemum pattern, and in V8 agar with no distinct pattern. Minimum growth temperature 3°C, optimum 24–30°C, and maximum 33°C.

Conditions for growth and sporulation

Sporangia form in water; hyphal swellings are sometimes observed in old water cultures.

Asexual phase

Sporangia nonpapillate, persistent; ovoid, obpyriform, ellipsoid, obovoid (30–53 L x 19–40 W µm) some with distorted shapes and some with tapered bases; presenting internal proliferation, produced on long, unbranched or loosely sympodial sporangiophores. Hyphal swellings globose, subglobose, with radiating hyphae produced on clusters or catenulated. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia smooth-walled, globose (25–52 µm diam); antheridia small (6–24 L x 9–16 W µm) predominately amphigynous and sometimes with digitate projections; oospores globose (23–44µm diam) plerotic, aplerotic, or slightly aplerotic.

Additional specimen(s) evaluated

Phytophthora sansomeana ex-type CPHST BL 55, duplicate of P8051 (World Phytophthora Collection), which is a duplicate of ex-type ATCC MYA-4455

Hosts and distribution

Distribution: North America (USA), Asia (China)
Substrate: roots, collar
Disease note: root rot
Host: Glycine max (Fabaceae), various other hosts

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

Additional info:

Additional references and links

Fact sheet author

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