Phytophthora insolita

Name and publication

Phytophthora insolita Ann & Ko (1981)

Ann PJ and Ko WH. 1980. Phytophthora insolita, a new species from Taiwan. Mycologia 72: 1180–1185.


from Ann and Ko (1980)




Latin, insolitus (unusual), referring to sex organs of the species


Type: TAIWAN, isolated from soil in citrus orchard by floating pieces of young citrus leaves on soil slurries from from Yunching, Changhua, collected in 1979 by P. J. Ann TAI 5131 (holotype: dried culture), Herbarium of Department of Botany, National Taiwan University, Taipei, Taiwan

Ex-type: CBS 691.79 and ATCC 38789

Ex-type in other collections

CBS 691.79 = ATCC 38789 = P6195 (WOC/WPC), IMI 288805, CMW 31063, PMC 5-1 P.J.Ann & W.H.Ko, CPHST BL 144 (Abad), 38E1 (Yang)

Molecular identification

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

Phytophthora insolita isolate CPHST BL 144 (= P6195 WPC) = ITS rDNA MG865515, COI MH136909

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

Clade 9b

Morphological identification

Colonies and cardinal temperatures

Colony morphology on V8-A, PDA, and MEA with chrysanthemum pattern. The minimum temperature for growth is 9°C, the optimum is 32°C, and the maximum is 38°C.

Asexual phase

Sporangia nonpapillated; persistent; ovoid, obpyriform, ellipsoid (38–70 µm long x 27–40 µm wide), sometimes with tapered bases; presenting internal nested and extended proliferation; originated in unbranched sporangiophores. Hyphal swellings globose, subglobose, elongate, obpyriform, produced single or in lobate chains. Chlamydospores globose and thin-walled.

Sexual phase

Sterile. Globose smooth-walled oogonia with no antheridia and plerotic oospores are sometimes produced in single cultures.

Specimen(s) evaluated

Phytophthora insolita ex-type CPHST BL 144 = P6195 (World Phytophthora Collection)

Hosts and distribution

Distribution: Asia (India, Taiwan), North America (USA: OH)
Substrate: soil, leaves
Disease note: foliar necrotic lesions and twig dieback (Testa et al. 2005)
Host: Rhododendron sp. (Ericaceae); able to infect Malus domestica (apple, Rosaceae) and Cucumis sativus (cucumber, Cucurbitaceae) fruits when inoculated (Erwin & Ribeiro 1996)

Retrieved January 31, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional info:
Host: Citrus spp.

Additional references and links

Fact sheet author

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