Phytophthora amaranthi

Name and publication

Phytophthora amaranthi Ann & Ko (2016)

Ann P, Huang J, Tsai J, Ko W. 2016. Morphological, molecular, and pathological characterization of Phytophthora amaranthi sp. nov. from amaranth in Taiwan. J. Phytopathol. 164: 94–101.

Corresponding author:


from Ann et al. (2016)




refers to the genus name of the host


Type: TAIWAN. Collected from Amaranthus tricolor in Yunlin F0027621 (dried culture), deposited at the Fungal Collection, National Museum of Natural Science, Taichung, Taiwan.

Ex-type: Culture CH30042 (from isolate TARI28041) deposited at the Culture Collection and Research Center, Food Industry Research and Development Institute, Hsinchu, Taiwan.

Sequences for ex-type in original manuscript: ITS GU111585

Ex-type in other collections

CH30042 = TARI 28041 = P20892 (WPC) = CPHST BL 174 (Abad)

Molecular identification

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

Phytophthora amaranthi isolate CPHST BL 174 (=TARI 28041) ITS rDNA MG783373, COI MH477739

Sequences of selected specimens

Phytophthora amaranthi isolate CPHST BL 175 (=TARI 27147) = ITS rDNA MG783374, COI MH136993
Phytophthora amaranthi isolate CPHST BL 176 (=TARI 29352) = ITS rDNA MG783375, COI MH136994

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

Clade 2b

Morphological identification

adapted from Ann et al. (2016)

Colonies and cardinal temperatures

Colony morphology after 5 days on V8-A, PDA, and MEA uniform. Minimum growth temperature 8°C, maximum 32°C, and optimum 24°C.

Asexual phase

Sporangia semipapillate, occasionally bipapillate (1.5%); persistent or caducous (20–30%), with short to medium pedicel (up to 12 μl length); spherical, ovoid to obpyriform, 40–70 (av. 52.2 μm long) x 30–50 (av. 38.2 μm wide); originated on simple sympodium or branched sporangiophores. Hyphal swellings absent. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia terminal, smooth-walled, spherical, globose to subglobose, 26–38 (av. 32.8 μm diam.); antheridia amphigynous; oospores aplerotic 20–28.8 (av. 32 μm diam.).

NOTE: Figures in original publication show only semi-papillate sporangia. Description refers to papillate sporangia.

Additional specimen(s) evaluated

Phytophthora amaranthi CPHST-BL #174 (Abad) duplicate of the ex-type CH30042 (from isolate TARI28041) donated by Dr. J. Huang 

Hosts and distribution

Distribution: Asia (Taiwan)
Substrate: leaves, roots, and stems of innoculated plants
Disease note: leaf blight, basal stem rot, and root rot
Hosts: Amaranthus tricolor, A. viridis (Amaranthaceae)

Retrieved January 18, 2018 from U.S. National Fungus Collections Nomenclature Database.

Quarantine status

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

Additional references and links

  • Phytophthora DATABASE: Phytophthora amaranthi
  • Q-bank: Phytophthora amaranthi
  • SMML USDA-ARS: Phytophthora amaranthi
  • EPPO Global Database: Phytophthora amaranthi
  • CABI Invasive Species Compendium: Phytophthora amaranthi
  • EPPO Global Database: Phytophthora amaranthi
  • Encyclopedia of Life (EOL): Phytophthora amaranthi
  • Index Fungorum (IF): Phytophthora amaranthi
  • Plantwise Knowledge Bank: Phytophthora amaranthi

Fact sheet author

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