Phytophthora gregata

Name and publication

Phytophthora gregata Jung, Stukely & Burgess (2011)

Jung T, Stukely MJC, Hardy GE StJ, White MD, Paap T, Dunstan WA, and Burgess TI. 2011. Multiple new Phytophthora species from ITS Clade 6 associated with natural ecosystems in Australia: evolutionary and ecological implications. Persoonia 13: 13–39.


from Jung et al. (2011)



Synonyms: was referred to as P.sp.7 by Burgess et al. (2009) and as taxon raspberry by Brasier et al. (2003)


refers to the abundant hyphal aggregations regularly formed by all isolates (gregata Latin = aggregated, in clumps)


Type: WESTERN AUSTRALIA, Busselton, from rhizosphere soil of dying Patersonia sp., 2009, VHS, holotype MURU 462 (dried culture on V8A, Herbarium of Murdoch University, Western Australia)

Ex-type: CBS 127952 and VHS 21962

Sequences for ex-type in original manuscript: CBS 127952 = ITS rDNA HQ012942, HSP90 HQ012904, cox1 HQ012858

Ex-type in other collections

CBS 127952 = VHS 21962 = P19588 (WOC/WPC), CPHST BL 37 (Abad), 62B9 (Yang)

Molecular identification

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

Phytophthora gregata isolate CPHST BL 37 (= P19588) ITS rDNA MG865503, COI MH477746

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

Clade 6b

Morphological identification

Colonies and cardinal temperatures

Colony morphology is faintly striate, stellate, or uniform on V8A, CA, MEA and PDA, but growth is denser on MEA and PDA. Minimum growth temperature 7.5°C, optimum 25°C, and maximum 32.5°C.

Conditions for growth and sporulation

Sporangia are produced in water cultures (soil extract or river water) and not observed in solid media. Oogonia are formed readily in single-strain culture on CA and V8A after about 10 d.

Asexual phase

Sporangia are nonpapillate, persistent, and usually ovoid or limoniform in shape. Sporangia average 51.0 ± 13.8 × 30.5 ± 5.9 μm (overall range 25.7–102.3 × 14.8–50.7 μm). Sporangiophores usually in simple sympodia and internal proliferation, both nested and extended, occurs in chains. Hyphal swellings are abundant as were hyphal aggregations. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia are globose, often with a tapering base, with smooth walls turning golden brown on maturity, average size 36.8 ± 4.1 mm (23.9–50.9 µm). Oospores are aplerotic, globose, with a large ooplast and thick walls, average size 31.6 ± 4.0 µm (21.4–45.3). Antheridia paragynous.

Most typical characters

Phytophthora gregata can be differentiated from other species from ITS Clade 6 by the production of hyphal aggregates.

Specimen(s) evaluated

Australia, Western Australia, Busselton, from rhizosphere soil of dying Patersonia sp., 2009, VHS, CBS 127952 = VHS 21962; from dying Hakea sp. VHS 21961; Lancelin, from Xanthorrhoea preissii, 2001, VHS 9854; Byford, from native forest, 1995, DCE68; Scott River, 2009, VHS 21992; Cataby, from dying Banksia prionotes, 1996, HSA 2356; Nannup, from rhizosphere of Pinus radiata, 1981, MJS 235; MJS 238; Victoria, Toolangi State Forest, from rhizosphere of a Eucalyptus sp., 2008, MUCC 759; Devlins Bridge from pasture, 2008, MUCC 760

Additional isolates: CPHST BL 37 = P19588 WPC

Hosts and distribution

Distribution: Australia, North America (USA: OR)
Substrate: associated with roots of dying plants
Host: diverse hard and softwood posts

Retrieved January 30, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional info:
Western Australia, Victoria
Substrate: roots, collars, and rhizosphere soil
Disease note: No pathogenicity trials have been conducted.
Hosts: rarely isolated in associated with other Phytophthora species in rhizosphere soil collected in wetter areas

Additional references and links

Burgess TI, Webster JL, Ciampini JA, White DW, Hardy GESJ, Stukely MJC. 2009. Re-evaluation of Phytophthora species isolated during 30 years of vegetation health surveys in Western Australia using molecular techniques. Plant Disease 93: 215–223.

Brasier CM, Cooke DEL, Duncan JM, Hansen EM. 2003. Multiple new phenotypic taxa from trees and riparian ecosystems in Phytophthora gonapodyides – P. megasperma ITS Clade 6, which tend to be high-temperature tolerant and either inbreeding or sterile. Mycological Research 107: 277–290.

Fact sheet authors

Treena Burgess, Ph.D., Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, Australia; Z. Gloria Abad, Ph.D., USDA-APHIS-PPQ-S&T Beltsville Laboratory, United States of America