Phytophthora tropicalis

Name and publication

Phytophthora tropicalis Aragaki & Uchida (2001)

Aragaki M and Uchida JY. 2001. Morphological distinctions between Phytophthora capsici and P. tropicalis sp. nov. Mycologia 93: 137–145.

Corresponding author:


from Aragaki and Uchida (2001)




Type: UNITED STATES OF AMERICA collected from macadamia raceme (Macadamia integrifolia) inflorescence on Macadamia orchard at Keaau, island of Hawaii by M. Aragaki (isolate H245) on 23 January 1975 (HOLOTYPE, CBS, dried culture of CBS 434.91)

Ex-type: CBS 434.91

Ex-type in other collections

CBS 434.91 = P10329 (WOC/WPC), CPHST BL 58 (Abad), ATCC 76651, ATCC MYA-4218, H245-24 (Aragaki), 35C8 (Yang)

Molecular identification

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

Phytophthora tropicalis isolate CPHST BL 58 (= P10329 WPC) = ITS rDNA MG865596, COI MH136987

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

Clade 2

Morphological identification

Colonies and cardinal temperatures

Colony morphology on PDA and MEA with chrysanthemum shape, on V-8A with no distinctive pattern or light chrysanthemum. Minimum temperature for growth 6°C, optimum 27–30°C, and maximum 33°C.

Conditions for growth and sporulation

Sporangia produced on agar and liquid cultures.

Asexual phase

Sporangia papillate; caducous with long, often curved pedicels: ovoid, oboviod, pyriform, ellipsoidal, or distorted shapes (18–63 µm length x 13–36 µm width), with tapered bases; originated on simple sympodial or umbellate sporangiphores. Hyphal swellings absent. Chlamydospores globose or subglobose (20–33 µm diam.), terminal or intercalary.

Sexual phase

Heterothallic. Oogonia smooth-walled, spherical (27–39 µm diam.); antheridia amphigynous, spherical, short cylindrical, or ovoid (13 x 16 µm diam.), sometimes with digitate projections; oospores plerotic, or slightly aplerotic, spherical (22–36 µm diam.) and thick-walled.

Most typical characters

Phytophthora tropicalis can be differentiated from P. capsici and other species except P. morindae in the production of umbellate sporangiophores and the shape of the caducous sporangia with long pedicels.

Specimen(s) evaluated

Phytophthora tropicalis ex-type CPHST BL 58, duplicate of P10329 (World Phytophthora Collection)

Hosts and distribution

Distribution: Pacific Islands (USA: HI); also reported from North America (USA: VA) and Europe (the Netherlands). This species may have been reported before 2001 as Phytophthora capsici; therefore, the full geographic distribution is unclear.
Substrate: leaves, stems, shoots
Disease note: wilt, dieback, shoot death
Host: 14 genera in 12 families

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