Phytophthora urerae

Name and publication

Phytophthora urerae GA Forbes & NJ Grünwald (2019)

Grünwald NJ, Forbes GA, Perez‐Barrera W, Stewart JE, Fieland VJ, Larsen MM. 2019. Phytophthora urerae sp. nov., a new clade 1c relative of the Irish famine pathogen Phytophthora infestans from South America. Plant Pathology 68 (3): 557–65.





referring to the host plant Urera laciniata from which it was first isolated and which was validated as a host plant following Koch’s postulates


Type: Peru, San Ramon, Junin, isolated from plant host Urera laciniata in Peru, Collected by W. Perez-Barrera, holotype BPI893220

Ex-type: culture PSR27

Sequences for ex-type in original manuscript:  PSR27; ITS KR632862, cox1 KR632858, PITG11126 KR632939, ypt1 KR632913, β-tubulin KR632888

Molecular identification

Position in ITS phylogenetic tree

Clade 1c

Morphological identification

Colonies and cardinal temperatures

Colonies smooth to slightly stellate on rye B and V8A, and appeared cottony and petallate to stellate on PDA. Minimum growth temperature 6°C, optimum 20–25°C, and maximum 28°C.

Conditions for growth and sporulation

Sporangia produced on solid V8A. Oogonia are formed readily on agar within 7 days when paired with opposite mating type.

Asexual phase

Sporangia were semi-papillate to papillate, caducous, and predominantly ellipsoid in shape. Sporangia averaged 30 x 18 µm (overall range 20–36 x 14–22 µm). Hyphal swellings absent. Chlamydospores absent.

Sexual phase

Heterothallic. Oogonia smooth-walled, size ranged from 22–40 µm. Oospores plerotic, size ranged 18–35 µm. Antheridia amphigynous.

Most typical characters

Morphologically similar to other species in Clade 1c. Can be distinguished as it can only cause symptoms on a single host Urera laciniata.

Additional specimen(s) evaluated

Peru, San Ramon, Junin, foliage of Urera laciniata, collected by W. Perez-Barrera, PSR26; PSR28; PSR29; PSR30; PSR31

Hosts and distribution

Distribution: Peru
Substrate: leaf
Disease note: foliar blight on leaves of native plant Urera laciniata in Peru
Host: Urera laciniata

Additional references and links

none available

Fact sheet author

Treena Burgess, Ph.D., Phytophthora Science and Management, Harry Butler Institute, Murdoch University