Phytophthora colocasiae (to be redescribed 2022)

Name and publication

Phytophthora colocasiae Racib. (1900)

Raciborski, M. 1900. Parasitic algae and fungi, Java. Batavia Bulletin of the New York State Museum 19: 189 (pg. 9).





from Raciborski (1900)

Type: JAVA, on the leaves of Colocasia esculenta, spread to the whole island, without significant damage to effluent. Is also in the warm level (e.g. in Klaten), as in the present which are best suited for Soekaboemi and Buitenzorfg (in Old West Java which is an island of Indonesia) (taro leaf blight). (LOST)

Well-authenticated specimen selected by Gloria Abad:  CPHST BL 173 = P6317 WPC from Colocasia esculenta, INDONESIA (A2)

Selected specimen in other collections

CPHST BL 173 (Abad) = P6317 WPC 

Molecular identification

Voucher sequences for barcoding genes (ITS rDNA and COI) of selected specimens (see Molecular protocols page)

Phytophthora colocasiae isolate CPHST BL 173 (= P6317 WPC) = ITS rDNA MG865479, COI MH136875

Sequences for selected specimen in other sources
Position in ITS phylogenetic tree

Clade 2a

Morphological identification

Colonies and cardinal temperatures

Colony morphology after 7 days on V8-A, PDA, MEA with no distinct pattern. Minimum growth temperature 10°C, optimum 22°C, and maximum 30°C.

Asexual phase

Sporangia semipapillate; caducous with short pedicel (3–10 µm length); elongate, ovoid, or ellipsoid (48–55 µm long x 19–22 µm wide); some sporangia with tapered base or with lateral attachment; a conspicuous basal plug is observed in some sporangia; originated in simple or irregularly branched sporangiophores. Hyphal swellings globose, sub-globose, radiating hyphae, or irregular-shaped are occasionally observed. Chlamydospores globose, terminal or intercalary, observed in some isolates and rare in others (23–31 µm in diam.).

Sexual phase

Heterothallic. Oogonia with smooth wall (20–35 µm diam., av. 29.0 µm); antheridia amphigynous and subterminal; oospores aplerotic (18–30 µm diam., av. 23.0 µm).

Most typical characters

Phytophthora colocasiae is characterized by the presence of elongate sporangia with short pedicels.

Specimen(s) evaluated

Phytophthora colocasiae CPHST BL 173, duplicate of isolate P6317 (World Phytophthora Collection)

Hosts and distribution

Distribution: Africa (Ethiopia, East Africa, Fernando Po), Asia, Caribbean (Dominican Republic), North America (USA: CA, NC, HI), Pacific Islands, South America (Brazil, Argentina)
Substrate: leaves, corms, stems
Disease note: leaf blight, corm rot, wilt; also stem canker and black stripe of rubber
Hosts: Colocasia esculenta (taro) and other Aracaceae; also six genera in five other families

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

Additional references and links

Ann PJ, Kao CW, Ko WH. 1986. Mating-type distribution of Phytophthora colocasiae in Taiwan. Mycopathologia 93: 193-194.

Brooks, F. 2011. Taro leaf blight. APSnet Plant Disease Lessons.

Ko WH. 1979. Mating-type distribution of Phytophthora colocasiae on the island of Hawaii. Mycologia 71: 434-437.

Lin M. and Ko W. 2008. Occurrence of isolates of Phytophthora colocasiae in Taiwan with homothallic behavior and its significance. Mycologia 100: 727-734.

Fact sheet author

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