Phytophthora citricola

Name and publication

Phytophthora citricola Sawada (1927)

Sawada K. 1927. Descriptive catalogue of the Formosan fungi III. Report of the Department of Agriculture, Government Research Institute of Formosa 27: 1–62.





from Sawada (1927)

Type: TAIWAN, Formosa from fruit of Citrus sinensis, collected in 1927 IMI 21173

Ex-type: CBS 221.88

NOTE: Translation from the original manuscript in Japanese into English was provided by Dr. Motoaki Tojo at Osaka Prefecture of Japan (G. Abad 4.7.2018).

Ex-type in other collections

CBS 221.88 = P0716 (WPC), P1689 (WPC), ATCC 60440, NCTC3057, N107 (Gallegly, West Virginia U), CPHST BL 34 (Abad), 33H8 (Yang)

NOTE: Caution should be taken when identifying Phytophthora citricola as there are numerous misidentifications of this species in NCBI. It is recommended that sequences from specimens of the ex-type be used to correctly identify to species level.

Molecular identification

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

Phytophthora citricola isolate CPHST BL 34 (= P0716 WPC) = ITS rDNA MG865475, COI MH136871

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

Clade 2c

Genome sequence

Phytophthora citricola strain ex-type P0716. Accession genome USDA_Pcit_BL34_1.0 reference, BioProject PRJNA555328, USDA-APHIS-PPQ-S&T (2019), Srivastava et al 2022

Morphological identification

Colonies and cardinal temperatures

Colonies on V8-A, PDA, and MEA with chrysanthemum growth pattern, on PDA chrysanthemum with sparse aerial mycelium. Minimum growth temperature 3°C, optimum 24°C, maximum 30°C.

Conditions for growth and sporulation

Sporangia and oospores abundantly produced in V8 agar under 10% soil solution.

Asexual phase

Sporangia semipapillate and persistent; ovoid, globose, ellipsoid, obpyriform, and distorted shapes (28–78 x 21–47 µm) and bipapillate originated in single or sympodially branched sporangiophores. Hyphal swellings absent. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia smooth-walled, round base, occasionally tapered base (21–44 µm diam.); antheridia paragynous, rarely amphyginous (12–13 x 8–10 µm diam) attached near the oogonial stalks; oospores predominantly plerotic (18–38 µm diam.) with thick oospore wall.

Most typical characters

Phytophthora citricola is characterized by the presence of mostly ovoid semipapillate sporangia, paragynous antheridia attached near the oogonial stalks, and oogonia occasionally with tapered base.

Specimen(s) evaluated

Phytophthora citricola CPHST BL 34, duplicate of P0716 (World Oomycetes/Phytophthora Collection)

Hosts and distribution

NOTE: Information for P. citricola in many sources appears to correspond to P. plurivoraP. pini and other species in P. citricola "complex" (see phylogenetic tree figure).

Most isolates identified as P. citricola prior to 2009 are most likely to correspond to Phytophthora plurivora or P. pini. It is possible that the correct distribution for P. citricola is in Argentina, Australia, Canada, Japan, China, South Africa, Spain, Taiwan, and the USA (CA) (based on available sequences in NCBI). These sequences are associated with citrus and hybrid verbena (G. Abad, 9.12.18).

Distribution: cosmopolitan
Substrate: roots, fruits, stems, bark of trunks
Disease note: brown rot of oranges, black root of hops, root rot and cane die-back of raspberry, die-back of rhododendron, and basal rot of tomato seedlings (Waterhouse & Waterston 1966)
Hosts: 75 genera in 38 families

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

Quarantine status

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

Additional references and links

Scott PM, Burgess TI, Barber PA, Shearer BL, Stukely MJC, Hardy GE, and Jung T. 2009. Phytophthora multivora sp. nov., a new species recovered from declining Eucalyptus, Banksia, Agonis and other plant species in Western Australia. Persoonia 22: 1-13.

Jung T and Burgess TI. 2009. Re-evaluation of Phytophthora citricola isolates from multiple woody hosts in Europe and North America reveals a new species, Phytophthora plurivora sp. nov. Persoonia 22: 95-100.

Fact sheet author

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