Phytophthora sojae (to be redescribed 2022)

Name and publication

Phytophthora sojae Kaufm. & Gerd. (1958)

Kaufmann MJ and Gerdemann JW. 1958. Root and stem rot of soybean caused by Phytophthora sojae n. sp. Phytopathology 48: 201–208.





from Kaufmann and Gerdemann (1958)

Type: UNITED STATES OF AMERICA, collected from roots and stems of soybean (Glycine max) in Illinois, Ohio, North Carolina, Missouri, and Indiana, USA, and in Ontario, Canada. The type is represented by a culture isolated from a diseased soybean stem from a field near Blackstone, Illinois in 1955. Material of the type has been placed in the Herbarium of the University of Illinois, Urbana.

Ex-type: LOST

Well-authenticated specimens selected by Gloria Abad: 
Selected specimen #1: CPHST BL 180 = P3248 (WPC) from UNITED STATES OF AMERICA, Glycine max, Illinois
Selected specimen #2: CPHST BL 56G = P3114 (WPC) from UNITED STATES OF AMERICA, Glycine max, Wisconsin

Selected specimen in other collections

P3248 (WOC/WPC) = CBS 382.61, ATCC 16706, IMI 82069, N10, Phyt-B, Gerdemann (Chamberlain), CPHST BL 180 (Abad)

Molecular identification

Voucher sequences for barcoding genes (ITS rDNA and COI) of selected specimens (see Molecular protocols page)

Phytophthora sojae isolate CPHST BL 180 (= P3248 WPC) = ITS rDNA MG865587, COI MH136979

Phytophthora sojae isolate CPHST BL 56G (= P3114 WPC) = ITS rDNA MG865588, COI MH136980

Sequences for selected specimen(s) in other sources
Position in ITS phylogenetic tree

Clade 7b

Morphological identification

Colonies and cardinal temperatures

Colony after 7 days of growth on potato dextrose agar and malt extract agar is very small, and on V8A grows well and with no defined pattern. Minimum growth temperature 10°C, optimum 22–30°C, and maximum 33°C.

Asexual phase

Sporangia nonpapillate; ovoid, ellipsoid, obpyriform, obovoid (43–101 L x 24–55 W µm) with tapered base, originated in simple sympodial and undifferentiated sporangiophores, sometimes showing internal and external proliferation. Hyphal swellings intercalary, spherical to irregular in shape. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia spherical to subspherical (24–45 x 23–41 µm), some with distorted shapes, some with tapered base, some with tangled or knotted hyphae around the antheridium; antheridia predominantly paragynous (9–18 L x 8–16 W µm), frequently with a single long spine or digitate projection; oospores plerotic, aplerotic, and slightly aplerotic (18–39 µm diam).

Specimen(s) evaluated

Phytophthora sojae CPHST BL 180, duplicate of P3248 (World Phytophthora Collection)

Phytophthora sojae CPHST BL 56G, P3114 (World Phytophthora Collection) Wisconsin, soybean (Glycine max) (Maxwell #115)

Hosts and distribution

Distribution: Australia, North America (Canada, USA); also reported from South America (Brazil, Chile), Asia (Korea, China) and New Zealand
Substrate: roots, stems
Disease note: root and stem rot of soybeans; seedling wilt, seedling blight of lupines
Host: Glycine max (soybeans), Lupinus spp. (lupine) (Fabaceae); also reported from six other genera in five families

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

Quarantine status

Phytophthora sojae is listed in the U.S. Regulated Plant Pest Table (last modified Nov. 15, 2017).

Additional references and links

Fact sheet author

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