Phytophthora constricta

Name and publication

Phytophthora constricta Rea, Stukely & Jung (2011)

Rea AJ, Burgess TI, Hardy GE StJ, Stukely MJC, and Jung T. 2011. Two novel and potentially endemic species of Phytophthora associated with episodic dieback of Kwongan vegetation in the south-west of Western Australia. Plant Pathol. 60: 1055–1068.

Corresponding author:


from Rea et al. (2011)




refers to the fragile constriction of most sporangiophores towards the sporangial base


Type: AUSTRALIA, Fitzgerald River National Park, isolated from soil sample collected in dying native Kwongan vegetation, August 2006, M. Stukely. Holotype: MURU 454 (dried culture on V8A in the Herbarium of Murdoch University, Western Australia)

Ex-type: CBS 125801 and VHS 16130

Sequences for ex-type in original manuscript: Phytophthora constricta CBS 125801 = ITS HQ013225, coxI HQ013207

Ex-type in other collections

CBS 125801 = VHS 16130 = P19614 (WPC), CPHST BL 61 (Abad), 55C3 (Yang)

Molecular identification

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

Phytophthora constricta isolate CPHST BL 61 (= P19614 WPC) = ITS rDNA MG865480, COI MH136876

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

Clade 10a

Genome sequence

Phytophthora constricta strain ex-type BL 61. Accession genome USDA_Pcon_61_1.0 reference, BioProject PRJNA612532, USDA-APHIS-PPQ-S&T (2020)

Morphological identification

Colonies and cardinal temperatures

Colony morphology is petaloid on CA, V8A, MEA, and PDA. Minimum growth temperature 5°C, optimum 22.5°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 14 d.

Asexual phase

Sporangia are nonpapillate, persistent, and ovoid to broad-ovoid in shape. Sporangia average 59.8 ± 8.7 x 48.8 ± 7.4 mm (total range 39.1–83.9 x 31.4–68.8 mm). Sporangiophores in simple sympodia, constricted towards the base of the sporangium, with internal proliferation, both nested and extended. Hyphal swellings ellipsoid, but rare. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia are predominantly globose with smooth walls, although elongated and eccentric oogonia are observed, average size 48.0 ± 4.8 mm (31.8–59.6 µm). Oospores are slightly aplerotic, globose, turning pale golden-brown on maturity, average size 40.4 ± 4.3 µm (23.8–49.8 µm). Antheridia are paragynous.

Most typical characters

The most typical feature of Phytophthora constricta is the constriction of the sporangiophores toward the base of the sporangia.

Specimen(s) evaluated

Australia; Western Australia, Fitzgerald River National Park, isolated from soil sample collected in dying native kwongan vegetation, August 2006, M. Stukely CBS 125801 = VHS 16130; VHS 16127; VHS 16134; from Banksia cirsioides, VHS 16125; from Banksia falcate, DDS 3543; Nannup, from Pinus radiata, July 1980, DCE 177; MJS186

Additional isolates CPHST BL 61 = P19614 WPC

Hosts and distribution

Distribution: Australia
Substrate: roots, collar; isolated from soil
Disease note: root and collar rot
Host: Proteaceae

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

Additional info:
Distribution: Western Australia and Victoria
Substrate: roots, collars, and rhizosphere soil
Disease note: pathogenic toward Banksia attenuata
Hosts: numerous Proteaceous plant species including Banksias spp., Hakea spp., Adenanthos spp., and Isopogon spp.

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.

Dick MA, Dobbie K, Cooke DEL, Brasier CM. 2006. Phytophthora captiosa sp. nov. and P. fallax sp. nov. causing crown dieback of Eucalyptus in New Zealand. Mycological Research 110: 393-404.

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