Phytophthora capsici

Name and publication

Phytophthora capsici Leonian (1922)

Leonian LH. 1922. Stem and fruit blight of pepper caused by Phytophthora capsici species nov. Phytopathology 12: 401–408.


from Leonian (1922)




Phytophthora parasitica var. capsici (Leonian) Sarej., Annales de l'Institut Phytopathologique Benaki 2: 44 (1936) [MB353070]
= Phytophthora hydrophila Curzi, Riv. Patol. veg.: 1 (1927) [MB267501]


Type: UNITED STATES OF AMERICA, parasitic on stems and fruit of chile pepper (Capsicum annuum), State College, New Mexico. L. H. Leonian 1919

Ex-type: CBS 128.23 (deposited by Leonian in 1923) (A2 Type)

Ex-type in other collections

CBS 128.23P3605 (WPC), P1091 (WPC), ATCC 52771 A2, IMI 40502, CPHST BL 33 (Abad)

NOTE: IMI 40502 The Netherlands?? 

Molecular identification

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

Phytophthora capsici isolate CPHST BL 33G (= P1091 WPC) = ITS rDNA MG865467, COI MH136863

Selected specimen

Phytophthora capsici isolate CPHST BL 136 (= P1314 WPC) = ITS rDNA MG865468, COI MH136864

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

Clade 2b

Morphological identification

Colonies and cardinal temperatures

Colonies in V8-A, PDA, and MEA with no distinct pattern to light chrysanthemum pattern. Minimum temperature for growth is 6°C, optimum is 27°C, and maximum 33°C.

Asexual phase

Sporangia are papillate and semipapillate, occasionally with two or three apices; caducous with short, medium, and long pedicels (3 to 138 µm); subglobose, ovoid, obovoid, ellipsoid, fusiform, pyriform, to distorted shapes sometimes with tapered bases (9–41 x 12–47 µm). Sporangiophores unbranched, irregularly branched, and occasionally simple sympodial. Hyphal swellings are occasionally produced by some isolates in aqueous cultures and are globose, subglobose, produced individually or catenulate. Chlamydospores absent.

Sexual phase

Heterothallic. Oogonia are spherical or subspherical, smooth-walled, and hyaline to brown (22–40 µm diam); antheridia are amphigynous; oospores are aplerotic and plerotic (19–32 µm diam).

Most typical characters

Phytophthora capsici is characterized by its production of caducous, short, medium, and long pedicel sporangia which are subglobose to ellipsoid, and the absence of chlamydospores. It differs from closely related Phytophthora tropicalis which produces caducous, long pedicel, elongated-narrow sporangia with a tapering base, and chlamydospores frequently produced.

Specimen(s) evaluated

Phytophthora capsici ex-type CPHST BL 33 (A2) duplicate of P1091 (World Phytophthora Collection), a duplicate of ATCC 52771 (= ex-type CBS 128.23)

Additional isolates with 100% alignment in ITS rDNA with ex-type CPHST BL 33

CPHST BL 136 (A1) duplicate of P1314 (World Phytophthora Collection) from green bell pepper (Capsicum annuum) in California, USA

P223 (A2) from former NCSU - Plant Pathogen Identification Laboratory, Director Gloria Abad, collected from "chile jalapeño" (Capsicum annum) in Guatemala

Hosts and distribution

Distribution: cosmopolitan; tropical specimens may be Phytophthora tropicalis
Substrate: roots, fruits, stems, seedlings, pods, cotton bolls
Disease note: fruit, stem, and root rot; also seedling damping-off, leaf wilt
Hosts: Phytophthora capsici sensu lato infects 51 genera in 28 families, including Capsicum annuum (peppers), Solanum lycopersicum (tomato), and other Solanaceae. Aragaki & Uchida (2001) refers to isolates from non-Capsicum hosts to P. tropicalis, including isolates from Macadamia spp., Theobroma cacao (cacao), and other tropical crop species.

Retrieved January 29, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

Bowers JH, Martin FN, Tooley PW, and Luz ED. 2007. Genetic and morphological diversity of temperate and tropical isolates of Phytophthora capsici. Phytopathology 97: 492-503.

Fact sheet author

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