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IMI Descriptions of Fungi and Bacteria

Contents of Set 120 1994

Description No. Species Principal hosts

1191 Peronospora chlorae Blackstonia, Eustoma

1192 Peronospora conglomerata Erodium, Geranium

1193 Peronospora digitalidis Digitalis

1194 Peronospora euphorbiae Euphorbia

1195 Peronospora ficariae Ficaria, Ranunculus

1196 Peronospora knautiae Knautia, Scabiosa

1197 Peronospora oerteliana Primula

1198 Peronospora pulveracea Helleborus

1199 Peronospora rumicis Rumex

1120 Phytophthora nicotianae Citrus, Lycopersicon, Nicotiana

I S S U E D B Y T H E I N T E R N A T I O N A L M Y C O L O G I C A L I N S T I T U T E

An Institute of CAB INTERNATIONAL Egham, Surrey, United Kingdom

Mycopathologia 126: 41-64, 1994. © CAB International, 1994.

IMI DESCRIPTIONS OF FUNGI AND BACTERIA

The object of this series (formerly CMI Descriptions of Pathogenic Fungi and Bacteria, Sets 1-100 and CMI Descriptions of Fungi and Bacteria, Sets 101-102) is to provide, in convenient form, standardized, usually illustrated, descriptions of pathogens for use by plant pathologists and veterinary and medical mycologists. Besides a detailed description of the species, infor- mation is included on such subjects as the disease caused by the organism, its geographic distribution, physiologic specialization, transmission etc. Fungi of importance to other applied fields like biocontrol of insects and weeds, biodeterioration, biotechnology, industrial mycology etc. are also covered. References to key literature are also given. The information provided is based, wherever possible, on the IMI Distribution Maps of Plant Diseases, the Review of Plant Pathology (formerly Review of Applied Mycology) and the Review of Medical and Veterinary Mycology. The Descriptions are published in sets of 10, four sets being issued each year.

Mycopathologia 126: 43-44, 1994.

IMI Descriptions of Fungi and Bacteria No. 1191

PERONOSPORA CHLORAE

A, infected plant of Eustoma showing white mycelial patches on leaves. B, leaf of Eustoma showing hypophyl- lous conidiophores. C, conidiophore habit (diagrammatic). D, conidiophore and branches. E, conidiophore tips. F, conidia. G, oogonia in leaf tissue. H, young oogonium with attached antheridium. I, oospores. J, oospore showing densely reticulate wall. Bar = 3 cm for A; i cm for B; 40 ixm for C, D, G; 15 ixm for E, F, H-J .

Peronospora ehlorae de Bary, in Rabenhorst, Fungi europaei II, No. 1590, (1872).

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae bearing branched filamentous haustoria, some with a slight thickening at the base, in stem, leaf and root tissues. Conidiophores: hypophyllous, dense, arising from stomata, producing a white/grey felt-like layer; arborescent, colourless, aseptate, thin-walled, 300-600 x 10-12 txm, producing 3-6(-8) branches dichotomously in the upper half to one third, base swollen. Branches: 100-200 ixm long, straight, tips (6-)8-10(-20)txm long, unequal in length, subulate, often reflexed when more than 10 Ixm long, most diverging at an angle ~<90 °, a few > 90 °. Conidia: ellipsoid to ovoid, colourless to pale grey, non-papillate, (16-)20(-25) x (13-)14(-17) Ixm, thin-walled, some-

44

times with a small pedicel, germinating in water to give hyphae. Oogonia: spherical to ellipsoid, 26-46 txm diameter, with a thin wall, often with a laterally attached ovoid antheridium, 18 x 12 Ixm. Oospores: spherical, 25-30 txm diam, yellow-brown with a densely reticulate, thin wall.

HOSTS: BIackstonia (= Chlora) imperfoliata, B. perfoliata, B. serotina, Centaurium pulchellum, Erythraea centau- reum, E. roxburghii, Eustoma russelianum (= Lisianthus russelianus).

DISEASE: Downy mildew of Blackstonia and Eustoma.

GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Abkhasiya, Azerbaidzhan, Georgia. Asia-Tropical: India. Europe: Denmark, France, Hungary, Italy, The Netherlands, Portugal, Spain, Switzerland, Ukraine, UK (En- gland, Guernsey, Jersey), Yugoslavia.

PHYSIOLOGIC SPECIALIZATION: Peronospora chlorae f. cicendiae Molliard was described on Cicendia fili- formis and C. pusilla (= Exaculum pusiUum), but there is no experimental evidence for this designation.

TRANSMISSION: By conidia dispersed by wind or rain-splash. The role of oospores in disease transmission is unknown, bu.t they may act as perennating structures.

NOTES: This species has been reported in Italy (71, 2312) and Denmark (69, 6465) from leaves of Eustoma (= Lisianthus), a recently introduced commercial flower crop. Both seedlings and mature plants were affected. Disease incidence was reduced by avoiding excessive watering or manuring, and by careful management of humidity by ventilation. Although the significance of the disease is not yet known, it has the potential to be economically important.

LITERATURE: Aloj, Scalione, Nanni, & Marziana, Annali della Facoltdt degli Studi di Napoli, Portici 24: 45-52, 1990.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 45-46, 1994.

IMI Descriptions of Fungi and Bacteria No. 1192

PERONOSPORA CONGLOMERATA

A, diagrammatic representations of conidiophores. B, C, conidiophore tips. D, conidiophore base. E, conidia. F, oogonia and oospores in leaf tissue. Bar = 40 p~m for A; 15 txm for B-F.

Peronospora conglomerata Fuckel, Fungi rhenani No. 25, 1863.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae bearing filamentous haustoria very sparsely. Conidiophores: arising from stomata, producing a dense, white, felt-like layer in irregular patches, later becoming brown/violet; arborescent, 200-300 x 8-10 p~m, colourless, aseptate, thin-walled, branching dichotomously 3-7 times in the upper half, base not swollen. Branches: 100-150 p,m long, flexuous, tips 10-25 p~m, unequal in length, subulate, straight or more often reflexed, diverging at an angle ~<90 °, occasionally >90 °. Conidia: spherical to subspherical, light brown, non-papillate, (19-)22(-24) x (16-)20(-22) ~m, thin-walled, germinating in water to give hyphae. Oogonia: formed in leaves, spherical to subspherical,

46

35-42 txm diam, with a thin occasionally folded wall, sometimes with a laterally attached ovoid antheridium, 8 x 10 Ixm. Oospores: spherical, 26-35 pxm diam with a smooth, thick (4-5 Ixm) yellow wall, contents mid to dark grey with a prominent eccentric ooplast.

HOSTS: Erodium ciconium, E. cicutarium, E. hoeffiianum, Geranium collinum, G. columbinum, G. dissectum, G. lucidum, G. macrorhizum, G. molle, G. ocellatum, G. phaeum, G. pratensis, G. purpureum, G. pusillum, G. pyrenaicum, G. robertianum, G. rotundifolium, G. solanderi, G. sylvaticum, G. transversale.

DISEASE: Downy mildew of Geranium species. Conidiophores occur over the entire undersurface of the leaf, which remains small and becomes crinkled and yellowish. In G. pusillum, a weak infection creates only light green patches on affected leaves, but a heavy infection reduces leaf size, and the blade often turns up, causing much tissue damage and subsequent leaf fall (39, 159).

GEOGRAPHICAL DISTRIBUTION: Africa: Canary Isles. Asia-Temperate: Armenia, Azerbaidzhan, Georgia, Israel, Kazakhstan, Kirgizistan, Uzbekistan, Stravropol, Turkmenistan. Asia-Tropical: India. Australasia: Aus- tralia (Qld), New Zealand. Europe: Austria, Czechoslovakia, Denmark, Eire, Finland, France, Germany, Hungary, Italy, Latvia, Lithuania, The Netherlands, Norway, Poland, Portugal, Romania, Russia (Krym, Smolensk, Pskov, Perm, Tatariya), Serbia, Spain, Sweden, Switzerland, Ukraine, UK (England, Scotland), Yugoslavia. North America: Canada (BC), USA (ID, WA).

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia dispersed by wind or rain-splash. The role of oospores in disease transmission is unknown, but they may act as perennating structures.

NOTES: Four species of Peronospora have been described on members of the Geraniaceae: P. beccarii Pass. and P. conglomerata on Geranium, and P. effusa-ciconia Beccari and P. erodii Fuckel on Erodium. Of these four names, P. conglomerata is the earliest,

LITERATURE: G~iumann, Beitriige zur Kryptogamenflora der Schweiz 5: 99, 1923; Gustavsson, Opera Botanica 3: 157-158, 1959.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 47-48, 1994.

IMI Descriptions of Fungi and Bacteria No. 1193

PERONOSPORA DIGITALIDIS

A, diagrammatic representation of conidiophore. B, conidiophore under SEM to show tips. C, conidiophore base. D, conidia. Bar = 40 txm for A; 15 ixm for B-D.

Peronospora digitalidis G~iumann, Beitrgige zur Kryptogamenflora der Schweiz 5: 162, 1923.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae. Conidiophores: dense, arising from stomata, producing a grey/brown to dark brown felt-like layer; arborescent, 350-450 x 7 - 10 txm, colourless, aseptate, thin-walled, branching dichotomously 4-7 times in the upper one third to one half, base very slightly swollen. Branches: 120-200 txm long, flexuous, tips 10-25 p~m long, mostly equal in length, only tapering in distal half, incurved, most diverging at an angle ~<90 °, a few >90 °. Spores: colourless to light grey, ellipsoid to ovoid, broadly tapered towards the base, sometimes with a small pedicel, non-papillate, (23- )29(-35) x (15-)20(-27) p,m, thin-walled, germinating in water to give hyphae. Oogonia: unknown.

HOSTS: Digitalis ferruginea, D. grandiflora (= D. ambigua), D. lutea, D. purpurea.

48

DISEASE: Downy mildew of Digitalis spp. Leaf lesions are hypophyllous, dark brown, spherical, initially 1-2 cm diam, eventually coalescing.

GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Azerbaidzhan, Georgia. Europe: Czechoslovakia, France, Germany, Lithuania, Norway, Poland, Romania, Switzerland, Ukraine, UK (England, Scotland, Wales).

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia dispersed by wind or rain-splash.

NOTES: There are thirty-one described species of Peronospora on members of the Scrophulariaceae. Early records are often under the name Peronospora grisea (Unger) Unger.

LITERATURE: Gfiumann, Beitrgige zur Kryptogarnenflora der Schweiz 5: 162, 1923.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 49-50, 1994.

IMI Descriptions of Fungi and Bacteria No. 1194

PERONOSPORA EUPHORBIAE

A, diagrammatic representations of conidiophores. B, conidiophore. C, conidiophore base. D, conidia. E, oogonium and oospore. F, oogonia and oospores in leaf. Bar = 40 txm for A; 15 Ixm for B-F.

Peronospora euphorbiae Fuckel, Fungi rhenani No. 40, 1863.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae bearing filiform, branched haustoria. Conidiophores: arising from stomata, producing a dense, grey/white felt-like layer in irregular patches; arborescent, 180-400 x 4-7 Ixm, colourless to light brown, aseptate, thin-walled, branching dichotomously 5-7 times in the upper half to two thirds, base swollen. Branches: 80-130 Ixm long, most straight, sometimes flexuous, tips (6-)10-25 p,m long, approximately equal in length, diverging at an angle/>90 °, occasionally <90 °. Conidia: spherical to ovoid, light brown to light grey, non-papillate, (16-)18(-20) x (12- )16(-18) txm, germinating in water to give hyphae. Oogonia: (sub)spherical, 30-45 ixm diameter with a thin, folded, yellow-brown wall. Oospores: 30-35 Ixm diam with a light yellow, thick (4-5 pom) wall and a few, sparse, small tubercles, appearing as points.

50

HOSTS: Euphorbia dulcis, E. paralias, E. peploides, E. peplus, E. platyphylla, E. prostrata, E. serpens, E. serpyllifolia, E. serratula (= E. stricta).

DISEASE: Downy mildew of Euphorbia species. Leaf lesions are hypophyllous, but superficial in E. paralias, as it has stomata on the upper surface of its leaves, which curl upwards.

GEOGRAPHICAL DISTRIBUTION: Africa: South Africa. Asia-Temperate: Japan. Europe: France, Italy, Ma- jorca, Poland, Romania, Spain, Switzerland, UK (England). North America: USA (SD, TX).

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia which are dispersed by wind or rain-splash. The role of oospores in disease transmis- sion is unknown, but they may serve as perennating structures.

NOTES: Peronospora andina Speg., P. chamaesyc& G.W. Wilson, P. cyparisiae de Bary, P. embergeri Mayor & Viennot-Bourgin, P. esulae G~iumann, P. euphorbiae-glyptospermae G~iumann, P. euphorbiae-thymifoliae Sa- wada, P. favargeri Mayor & Viennot-Bourgin, P. hypericifoliae Sinha & Mathurand, P. valesiaca G~iumann have also been recorded on members of the Euphorbiaceae.

LITERATURE: G~iumann, Beitriige zur Kryptogamenflora der Schweiz 5: 322, 1923; Viennot-Bourgin, Encyclop& die Mycologique 26: 122, 1956.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 51-52, 1994.

IMI Descriptions of Fungi and Bacteria No. 1195

PERONOSPORA FICARIAE

A, diagrammatic representations of conidiophores. B, conidiophore. C, conidiophore base. D, conidia. E, oogonia and oospores in leaf. F, oogonia and oospores. Bar = 40 Ixm for A, E; 15 ixm for B-D, F.

Peronospora ficariae Tulasne ex de Bary, Annls Sci. nat., Bot., sdr. 4 20: 117, 1863.

Peronospora ranunculi Gfiumann, Beitrdge zur Kryptogamenflora der Schweiz 5: 16, 1923.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae bearing filamentous, branched haustoria. Conidiophores: arising from stomata, producing a dense white/grey felt-like layer; 200- 400 x 7-10 txm, colourless, aseptate, thin-walled, branching dichotomously 5-7 times in the upper half to one third. Branches: 150-200 Ixm long, flexuous, tips 8-10 ~m long, subulate, approximately equal in length, upper fork reflexed when long, diverging at an angle ~<90 °, occasionally >90 °. Spores: turbinate, occasionally ellipsoid,

52

light brown to violet, non-papillate, (22-)27(-32) x (17-)21(-26) Ixm, thin-walled, germinating in water to give hyphae. Oogonia: globose, 35-47 Ixm diam, thin wall, delimited from hyphae by septa. Oospores: 25-32 Ixm diam with a thick, yellow wall which has irregularly placed spikes and small protuberances on the surface.

HOSTS: Anemone coronaria, Helleborus purpurascens, Ficaria calthifolia, F. ledebourii, F. ficarioides, Ranunculus abortivus, R. acriformis, R. acer, R. acris, R. alpestris, R. auricomus, R. bulbosus, R. carpaticus, R. cassubicus, R. constantinopolitanus, R. crenatus, R. fascicularis, R. ficaria (= Ficaria verna), R. flammula ssp. flammula, R. languinosus, R. lateriflorus, R. lingua, R. montanus, R. nemorosus, R. oreophilus, R. oxyspermus, R. pedatus, R. pennsylvanicus, R. platanifolius, R. polyanthemus, R. pseudoplatanus, R. recurvatus, R. repens, R. sardous, R. scleratus, R. septentrionalis, R. uncinatus (= R. bongardi), R. velutinus.

DISEASE: Downy mildew of Ranunculus species, covering the entire leaf undersurface.

GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: China, Kazakhstan, Kirgizistan, Russia (Kamchatka), Stavropol, Japan. Australasia: New Zealand. Europe: Austria, Belgium, Belorussiya, Bulgaria, Czechoslovakia, Denmark, Eire, Estonia, Faeroes, Finland, France, Germany, Hungary, Iceland, Italy, Latvia, The Netherlands, Norway, Poland, Romania, Russia (Krym, Moscow, Pskov, Novgorod, St. Petersburg, Saratov, Smolensk, Tambov, Tatariya, Tula, Yaroslavl), Sweden, Switzerland, Ukraine, UK (England, Scotland, Wales, Channel Islands), Yugoslavia. North America: Canada (BC, Que), USA (AL, ID, MA, MI, OR, WI, WA, WY, NY). South America: Argentina, Dominican Republic.

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia dispersed by wind or rain-splash. The role of oospores in disease transmission is unknown, although they may act as perennating structures.

NOTES: The record on Helleborus purpurascens by Constantinescu & Negrean (62, 2330) assumes a broad species concept. A record on Delphinium depauperatum in the USA (WA) by Shaw & Yerkes (1952) is very doubtful. Tramier (40, 110) described a new species, Peronospora anemones, which was distinguished from Peronospora ficariae on the basis of host range, although the two species were morphologically indistinguishable (see Francis & Wilson, CMI Descriptions of Fungi and Bacteria No. 684, 1981).

LITERATURE: Gullino & Garibaldi, Colture Protette 13: 76-78, 1984; Gustavsson, Botaniska Notiser 112: 1-16, 1959; Shaw & Yerkes, Northwest Science 26: 20, 1952; Viennot-Bourgin, Encyclopddie Mycologique 26: 226- 227, 1956.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 53-54, 1994.

IMI Descriptions of Fungi and Bacteria No. 1196

PERONOSPORA KNAUTIAE

1

A, diagrammatic representation of conidiophores. B, conidiophore tips. C, conidiophore base. D, conidia. Bar = 40 Ixm for A; 15 ixm for B-D.

Peronospora knautiae Fuckel ex Schr6ter, in Cohn, Kryptogamen-Flora yon Schlesien 3: 251, 1886.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae bearing filamentous, branched haustoria. Conidiophores: arising from stomata, producing a moderately dense white/grey felt-like layer, later becoming violet-brown; 200-500 x 5-9 ~m, colourless, aseptate, thin-walled, branching dichoto- mously 3-6 times in the upper third to one quarter. Branches: 100-150 ixm long, ftexuous, tips 10-15 ~m long, approximately equal in length, subulate, straight, diverging at an angle/>90 °. Spores: ellipsoid to ovoid, hyaline, non-papillate, (22-)26(-29) x (16-)19(-22) Ixm, thin-walled, germinating in water to give hyphae. Oogonia: unknown.

HOSTS: Cephalaria transylvanica, Knautia arvensis, K. carpatica, K. caucasica, K. drymeia ssp. drymeia, K.

54

integrifolia, K. godeti, K. montana, K. silvatica, Pterocephalus plumosus, Scabiosa columbaria, S. lucida, S. ochroleuca, Succisa pratensis.

DISEASE: Downy mildew of Knautia and Scabiosa species. Leaf spots are violet or brown and sparse.

GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Azerbaidzhan, Stavropol, Turkmenistan. Europe: Aus- tria, Czechoslovakia, Denmark, Estonia, France, Germany, Italy, Latvia, Lithuania, Norway, Poland, Romania, Russia (Novgorod, Pskov, St. Petersburg, Yaroslavl), Sweden, Switzerland, Ukraine.

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia which are dispersed by wind or rain-splash.

NOTES: The record on Cephalaria by Constantinescu & Negrean (62, 2330) assumes a broad species concept, as Peronospora cephalariae Vincens has also been described on this host. Peronospora knautiae may be a different species to Peronospora violacea Berk., which also occurs on Knautia and Scabiosa, but which appears confined to the inflorescence, has much longer, more pointed spores, and also produces oospores.

LITERATURE: G~iumann, Beitrgige zur Kryptogamenflora der Schweiz 5: 238, 1923.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 55-56, 1994.

IMI Descriptions of Fungi and Bacteria No. 1197

PERONOSPORA OERTELIANA

A, diagrammatic representation of conidiophore. B, conidiophore tips. C, conidiophore base. D, conidia. Bar = 40 Ixm for A; 15 Ixm for B-D.

Peronospora oerteliana Kiihn, Hedwigia 23: 173, 1884.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae. Conidiophores: arising from stomata, uniform, producing a dense, white felt-like layer; 350-600 × 8-10 ixm, colourless, aseptate, thin-walled, branching dichotomously 4-7 times in the upper one third. Branches: 100-130 txm long, flexuous, tips 15-25 txm long, subulate, often unequal in length with a reflexed, longer upper branch, diverging at an angle/>90 °. Spores: subspherical, ellipsoid to ovoid, colourless to light grey, non-papillate, (18-)23(-26) x (17- )19(-23) p.m, thin-walled, germinating in water to give hyphae. Oogonia: see notes.

HOSTS: Primula acaulis, P. algida, P. elatior, P. juliae, P. officinalis, P. veris, P. vulgar&.

DISEASE: Downy mildew of Primula spp.

56

G E O G R A P H I C A L DISTRIBUTION: Asia-Temperate: Kazakhstan. Europe: Czechoslovakia, Denmark, Eire, France, Germany, Poland, Romania, Sweden, Switzerland, Yugoslavia, UK (England, Scotland).

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia which are dispersed by wind or rain-splash. The role of oospores in disease transmis- sion is unknown, but they may have a perennating function.

NOTES: Early records of Peronospora on Primula species are given under the name Peronospora candida Fuckel. Oogonia and oospores have seldom been recorded since the original description and a search of material at IMI failed to reveal any. Oogonia were described as being globose, 30-35 Ixm diameter with a thin wall, and oospores as being 30-35 ixm diam with a light brown, smooth or irregularly roughened wall.

LITERATURE: G~iumann, Beitriige zur Kryptogamenflora der Schweiz 5: 89, 1923.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 57-58, 1994.

IMI Descriptions of Fungi and Bacteria No. 1198

PERONOSPORA PULVERACEA

A

j

A, diagrammatic representation of conidiophore. B, conidiophore. C, conidiophore base. D, conidia. Bar = 40 p~m for A; 15 ixm for B-D.

Peronospora pulveracea Fuckel, Fungi rhenani No. 1, 1863.

Peronospora hellebori-purpurascentis Savulescu & Rayss, Herb. mycol, rom. No. 514, 1934.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae, forming filamentous haustoria, especially in the rhizome. Conidiophores: arising from stomata, producing a moderately dense white/ grey felt-like layer; 200-400 x 6-9 p.m, colourless, aseptate, thin-walled, branching dichotomously 4-6 times in the upper half to one third, slightly swollen base. Branches: 100-160 txm long, ftexuous, tips 10-15 Ixm long, subulate, straight or reflexed, often unequal in length, diverging at an angle />90 °. Spores: ellipsoid to ovoid, light violet, non-papillate, (26-)30(-35) × (22-)24(-26) ixm, thin-walled, germinating in water to give hyphae. Oospores: unknown.

HOSTS: Helleborus caucasicus, H. corsicus (= H. argutifolius), H. foetidus, H. niger, H. purpurascens, H. viridis.

DISEASE: Downy mildew of Helleborus species. May develop to cover the entire plant, aborting flowering and leaving the foliage, small, crisped and uniformly grey-brown. The fungus has been reported to destroy whole stands of plants.

58

GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Azerbaidzhan, Georgia. Europe: Austria, Denmark, Eire, France, Germany, Italy, The Netherlands, Poland, Portugal, Romania, Switzerland, UK (England), Yugoslavia.

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia which are dispersed by wind or rain-splash, and by perennation as mycelium in the rhizome.

NOTES: If a broad species concept is assumed, Peronospora pulveracea might be considered synonymous with Peronospora ficariae Tul. ex de Bary (62, 2330).

LITERATURE: Gfiumann, Beitriige zur Kryptogamenflora der Schweiz 5: 109, 1923.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 59-60, 1994.

IMI Descriptions of Fungi and Bacteria No. 1199

PERONOSPORA RUMICIS

A, diagrammatic representation of conidiophore. B, conidiophore tips. C, D, conidiophore bases. E, conidia. Bar = 40 ixm for A; 15 Ixm for B-E.

Peronospora rumicis Corda, Icon. fungi 1: 20, 1837.

Obligately biotrophic plant pathogen. Mycelium: intercellular, aseptate, colourless hyphae bearing simple filamentous, or peg-like haustoria. Conidiophores: arising from stomata, producing a very dense grey/violet felt- like layer, 200-400 x 9-11 ixm, colourless, aseptate, thin-walled, straight, branching sparsely and dichotomously 3-6 times in the upper third, base swollen. Branches: 90-120 Ixm long, straight, tips 8-12 txm long, stiff, nearly always unequal in length with a much shorter lower branch, diverging at an angle approximately 90 °, broad at tip. Spores: ellipsoid, grey/violet, non-papillate, (23-)26(-32) x (18-)20(-25) ixm, thin-walled, germinating in water to give hyphae. Oogonia: See notes.

HOSTS: Emex spinosa, Polygonum convolvulus, Rumex acetosa, R. acetosella, R. alpestris, (= R. arifolius), R. auriculatus, R. aviculare, R. hastatus, R. lunaria, R. longifolius, R. montanus, R. patienta, R. polyanthemus, R. repens, R. scutatus, R. thyrsifolius, R. tuberosus, R. vesicarius.

DISEASE: Downy mildew of Rumex. Both leaves and flowers are infected. On R. acetosella, the plant remains

60

upright following infection and the upper leaves crumple. In other Rumex species, infected leaves become covered in a very dense layer of violet-coloured felt on their undersurface, whereas a grey felt layer develops on flowers. Leaves become yellowish and their margins roll back (39, 159).

GEOGRAPHICAL DISTRIBUTION: Africa: Libya, Morocco, South Africa. Asia-Temperate: Azerbaidzhan, Georgia, Israel, Kazakhstan, Kirghizistan, Stavropol. Asia-Tropical: India. Australasia: New Zealand. Europe: Austria, Cyprus, Czechoslovakia, Denmark, Eire, Estonia, Faeroes, Finland, France, Germany, Hungary, Italy, Latvia, Norway, Poland, Romania, Russia (Novgorod, St. Petersburg, Smolensk, Yaroslavl), Serbia, Sweden, Switzerland, Ukraine, UK (England, Scotland), Yugoslavia.

PHYSIOLOGIC SPECIALIZATION: No evidence.

TRANSMISSION: By conidia which are dispersed by wind or rain-splash. Mycelium perennates in the root.

NOTES: This is the type species of the genus Peronospora. Briosi & Camara (1891) reported oospores ("winter spores") which were spherical with a very thick, yellowish wall around which the oogonial membrane persisted for a long time. However, oogonia and oospores were not recorded by subsequent investigators and were not found in material examined at IMI. Also, Briosi & Camara's record of P. rumicis on Polygonum convolvulus implies a broad species concept.

LITERATURE: Briosi & Cavara, I Funghi Parassiti delle Piante Coltivate od Utile p. 53, 1891. G~iumann, Beitriige zur Kryptogamenflora der Schweiz 5: 323, 1923.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.

Mycopathologia 126: 61-63, 1994.

IMI Descriptions of Fungi and Bacteria No. 1200

PHYTOPHTHORA NICOTIANAE

A, shrivelled tobacco seedling showing root blackening. B, tomato plant stem showing blackening and collapse. C, rosette colony pattern on corn meal agar. D, sporangia in water culture. E, discharged sporangium showing papilla, basal plug, swelling on the sporangiophore and external proliferation. F, sporangium showing lateral attachment. G, hyphal swelling with radiating hyphae. H, chlamydospores. I, young oogonia with amphigynous antheridia. J, oogonium with amphigynous antheridium and thick-walled oospore. Bar = 1 cm for A-C; 40 txm for D; 15 Izm for E-J.

Phytophthora nicotianae van Breda de Haan, Mededeelingen uit's Lands Plantentuin 15: 57, 1896.

Phytophthora melongenae Sawada, Noji ShikenjO Tokubetsu HOkoku (Spec. Rep. Formosa agric. Exp. Stn) 11: 77-79, 1915. Phytophthora nicotianae var. nicotianae (van Breda de Haan) Waterhouse, Mycol. Pap. 92: 14, 1963 (autonym). Phytophthora nicotianae var. parasitica (Dastur) Waterhouse, Mycol. Pap. 92: 14, 1963. Phytophthora parasitica Dastur, Mem. Dep. Agric. India bot. Ser. 5: 226, 1913. Phytophthora parasitica var. nicotianae (van Breda de Haan) Tucker, Res. Bull. Mo. agric. Exp. Stn 153: 173, 1931.

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Phytophthora parasitica var. parasitica (Dastur) Tucker, Res. Bull. Mo. agric. Exp. Stn 153: 173, 1931 (autonym). Phytophthora parasitica var. rhei Godfrey, J. agric. Res. 23: 21, 1923. Phytophthora tabaci Sawada, Rep. Govt. Res. Inst. Dep. Agric. Formosa 27: 37-38, 1927. Phytophthora terrestris Sherbakoff, Phytopathology 7: 127, 1917.

Facultatively necrotrophic plant pathogen. Mycelium dense or loose rosette, or with no pattern, and dome- shaped or low, spreading, aerial mycelium. Radial growth rate on V8 agar at 25 ° C, (3-)6(-10) mm/day. Hyphae coenocytic, 7-10 p~m diam. In 75% of cultures, swellings with radiating hyphae are formed in water within 5- 14 days. Growth or stasis at 5 °, good growth at 35 °, ca 50% of cultures showing stasis or growth at 40 °. Sporangia produced abundantly in liquid culture in light or dark, rarely and very weakly on solid agar in light or dark; predominately spherical, ovoid, obturbinate or ellipsoid with a prominent papilla, (14-)43(-74) x (12-)36(-60) p~m, length:breadth ratio (1.1:1-)1.2:1(-1.3:1); spherical sporangia often with 2 (very occasionally 3) papillae. In water, sporangia usually borne singly or in very loose sympodia of 2-4 sporangia, seldom in clusters, often laterally attached to sporangiophore, non-caducous. Chlamydospores present in ca 50% of cultures, spherical, (22-)33(-52) ~m diam, forming within 5-14 days, wall 3-4 Ixm thick with irregular subcellular inclusions, delimited from somatic mycelium by a septum. Oogonia spherical, (16-)26(-36) ~m diam, wall 1-2 txm thick, homogeneous contents, delimited from somatic hypha by a septum. Antheridia always amphigynous, cylindrical, 10-12 x 9-10 Ixm, unicellular. Oospores spherical, pale yellow when mature, (12-)24(-34) Ixm diam, oospore wall 2 Ixm thick, containing irregularly shaped subcellular inclusions.

DISEASE: Blackshank of tobacco, buckeye of tomato, root and fruit rot of capsicum, root rot of citrus.

HOSTS: Principally Lycopersicon esculentum, Nicotiana tabacum, Capsicum annuum and Citrus sp. A very large number of other agricultural and ornamental crops, both temperate and tropical, are also affected, including avocado, strawberry, pineapple, papaya, guava, eggplant and durian.

G E O G R A P H I C A L DISTRIBUTION: World-wide, but particularly common in the tropics and sub-tropics.

PHYSIOLOGIC SPECIALIZATION: Although there have been reports of host specificity among cultures of P. nicotianae, often small numbers of cultures were studied, and there have been as many reports of the lack of host specificity during cross-inoculation experiments. Fifteen cultures pathogenic to tobacco failed to produce the elicitor protein parasiticein, which was produced by six cultures not pathogenic to tobacco, suggesting a mechanism for physiological specialization (71, 6551).

TRANSMISSION: By zoospores in surface water and rainsplash. Chlamydospores (and oospores, when formed) act as perennating structures.

NOTES: Other synonyms are given in Waterhouse (1963). The history of the taxonomy and nomenclature of the fungus was reviewed by Ho & Jong (1989). Briefly, the description of P. nicotianae is based on discordant elements: the sporangia illustrated belong to P. nicotianae, but the oogonia belong to another organism (possibly a species of the genus Pythium). P. parasitica is identical to P. nicotianae, although this was not realised at the time, due to the mistake in the original illustration of P. nicotianae. Both names have been used for the fungus, although P. nicotianae predominates in Europe and Asia, whereas P. parasitica predominates in the Americas. Following the rule of priority in the International Code of Botanical Nomenclature (ICBN), the name P. nicotianae must be used.

In addition, the variety P. parasitica var. nicotianae, was described to distinguish the fungus causing black shank disease of tobacco from P. parasitica var. parasitica, the plurivorous pathogen. Two more varieties, P. nicotianae var. nicotianae and P. nicotianae var. parasitica were descibed on the basis of several morphological features, but without attribution of specific pathological characters. Plant pathologists have usually referred to the pathogen responsible for black shank disease of tobacco as P. parasitica var. nicotianae or P. nicotianae var. nicotinae. Other workers found it difficult to consistently separate these varieties, and some authors ignored them.

Many studies have examined the intraspecific variation in this fungus using a variety of approaches and methods: morphological (Ho & Jong, 1989), biochemical (Oudemans & Coffey, 1991), integrated using numerical methods (Hall, 1993), serological (Cristinizio, Scala & Noviello, 1983) and RFLP analysis of mitochondrial and chromosomal DNA (F6rster, Oudemans & Coffey, 1990). Often large populations from diverse hosts and geographical locations were used and there have been two consistent results. First, that there is no evidence to support separation of the species into two varieties, and second, that there is no correlation between morphology (or name) and pathogenicity.

Mycopathologia 126: 61-63, 1994.

IMI Descriptions of Fungi and Bacteria No. 1200 (continued)

PHYTOPHTHORA NICOTIANAE

The name P. nicotianae has priority over P. parasitica, but no holotype material was designated by van Breda de Haan. Therefore, the culture was neotypified by Hall (1993) to unequivocally link the name with herbarium material and a living culture.

LITERATURE: Cristinizio, Scala & Noviello, Annale della Facultg~ de Sciencie del'Universitd di Napoli, Portici 17: 77-89, 1983; F6rster, Oudemans & Coffey, Experimental Mycology 14: 18-31, 1990; Hall, Mycological Research 97: 559-574, 1993; Ho & Jong, Mycotaxon 35: 243-276, 1989; Oudemans & Coffey, Mycological Research 95: 1025-1046, 1991; Waterhouse, Mycological Papers 92: 1-22, 1963.

This sheet replaces IMI Description of Pathogenic Fungi nos. 34 & 35, issued 1964.

G. Hall

[Numbers in brackets, e.g. (62, 5055), refer to abstracts in the Review of Plant Pathology]

Issued by the International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, U.K.

Kluwer Academic Publishers. Printed in the Netherlands.

© CAB INTERNATIONAL, 1994. All rights reserved.

No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording, or otherwise, without the prior permission of the copyright owner.