Phytophthora mexicana (to be redescribed 2022)

Name and publication

Phytophthora mexicana Hotson & Hartge (1923)

Hotson JW and Hartge L. 1923. A disease of tomato caused by Phytophthora mexicana sp. nov. Phytopathology 13: 520–531 (pg 520).





from Hotson and Hartge (1923)

Type: MEXICO, collected form fruit of tomato (Lycopersicum esculentum Mill.) in the early summer 1917. The isolate was obtained from tomato shipped from Mexico into Seattle, Washington. Transfers were made to keep it alive until 1920 at which time the cultural study was begun.

Ex-type: LOST

Well-authenticated specimen selected by Gloria Abad: 
Selected specimen #1: P0646 (WPC) = CPHST BL 24 A2 type from Solanum lycopersicum, ARGENTINA

Selected specimen in other collections

P0646 (WPC) = CBS 554.88, ATCC 46731, IMI 92550, CPHST BL 24 (Abad)

Molecular identification

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

Phytophthora mexicana isolate CPHST BL 24 (= P0646 WPC) = ITS rDNA MG865540, COI MH136933

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

Clade 2b

Morphological identification

Colonies and cardinal temperatures:

Colonies on CMA, V8, and PDA xxxx. Minimum temperature for growth xx, optimum 24–27°C, and maximum 32°C.

Asexual phase

Sporangia papillate to semipapillate; persistent; ovoid, globose, irregular shape (16–33 x 16–77 µm), originated in simple and simple sympodial sporangiophores. Hyphal swellings absent. Chlamydospores occasionally produced and are globose, terminal, intercalary, and lateral.

Sexual phase

Homothallic. Oogonia terminal, smooth-walled (24–37 µm); antheridia predominantly amphigynous; oospores plerotic.

Specimen(s) evaluated

Phytophthora mexicana CPHST BL 24, duplicate of P0646 (World Oomycetes/Phytophthora Collection)

Hosts and distribution

Distribution: North America (Mexico, type); possibly introduced from the Netherlands (Erwin & Ribeiro 1996)
Substrate: fruit
Disease note: fruit rot; also black wilt and damping off
Host: Solanum lycopersicum (Solanaceae)

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

Additional references and links

Fact sheet author

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