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Braun & Dick—Leaf spot diseases of eucalypts 221
New Zealand Journal of Forestry Science 32(2): 221–234 (2002)
LEAF SPOT DISEASES OF EUCALYPTS
IN NEW ZEALAND CAUSED BY
PSEUDOCERCOSPORA SPECIES
UWE BRAUN
Martin-Luther-University, Institute of Geobotany and Botanical Garden,
Neuwerk 21, D-06099 Halle (Saale), Germany
and MARGARET A. DICK
New Zealand Forest Research Institute,
Private Bag 3020, Rotorua, New Zealand
(Received for publication 27 May 2002; revision 23 August 2002))
ABSTRACT
Specimens of Pseudocercospora on eucalypt foliage collected over the past 22 years
and held in the New Zealand Forest Research Institute Mycological Herbarium (NZFRI-M)
were examined. In addition to the previously recorded Pseudocercospora eucalyptorum
Crous et al., three new species of Pseudocercospora — P. acerosa sp. nov., P. crousii
sp. nov., and P. pseudobasitruncata sp. nov. — have now been described. These
descriptions can be used to identify the species found in New Zealand, and contribute to
the worldwide key to Pseudocercospora spp. on eucalypts.
Keywords: leaf spot diseases; new species; Eucalyptus; Pseudocercospora eucalyptorum;
Pseudocercospora spp.
INTRODUCTION
Cercospora eucalypti Cooke & Massee and C. epicoccoides Cooke & Massee, described
on Eucalyptus spp. from Australia, were the only species on this host genus treated by Chupp
(1954) in his monograph of Cercospora Fresen. Until 1989, all collections of Cercospora-
like hyphomycetes on eucalypts were assigned to these species, mostly to C. eucalypti. Dick
(1982, 1990) recorded C. eucalypti from New Zealand on a wide range of hosts. Crous et al.
(1989) examined type material of C. eucalypti and C. epicoccoides and pointed out that they
do not represent species of Cercospora or allied genera, but two different coelomycetes,
which were later placed in Phaeophleospora (Crous et al. 1997). Guo & Liu (1989)
misapplied the name C. eucalypti and reallocated it to Pseudocercospora, based on Chinese
material and Chupp’s (1954) treatment, but they did not examine type material. Crous et al.
(1989) introduced the new name Pseudocercospora eucalyptorum Crous et al. for a
common, widespread cercosporoid leaf spot fungus on a wide range of hosts, which was
usually deposited in herbaria as “Cercospora eucalypti”.
Reprint 2808
222 New Zealand Journal of Forestry Science 32(2)
The genus Eucalyptus, which originates in Australia and some islands immediately north
of the island continent, comprises more than 450 species. Numerous taxa are now planted
as forest or ornamental trees in various part of the world, stretching from Australia and New
Zealand to Asia, Africa, South America, and the United States. It could be supposed that the
enormous diversity of Eucalyptus has to be connected with a large diversity of cercosporoid
hyphomycetes pathogenic to this genus. During the course of comprehensive examinations
of leaf spot diseases of eucalypts caused by Mycosphaerella species and their anamorphs,
Crous (1998) treated 57 species. Twenty-three of the anamorph species were representatives
of Cercospora and allied genera, and 17 of these were species of Pseudocercospora. Crous
(1999) monographed Mycosphaerella including cercosporoid anamorphs on other hosts of
the Myrtaceae, excluding Eucalyptus. A comparison of cercosporoid leaf spot diseases on
various hosts of the Myrtaceae showed that eucalypts have their own specific species distinct
from taxa on other myrtaceous hosts.
On account of the new, more comprehensive, taxonomic knowledge of cercosporoid
hyphomycetes on eucalypts, a re-examination of collections from New Zealand deposited
at NZFRI-M was made to determine which species were masked under “Cercospora
eucalypti/Pseudocercospora eucalyptorum”. It could be demonstrated that four species of
Pseudocercospora are present in New Zealand, i.e., Pseudocercospora eucalyptorum and
three new undescribed species.
MATERIALS AND METHODS
All collections were mounted in distilled water and examined by standard light microscopy
(Olympus BX 50, Hamburg, Germany). Colourless structures were stained with cotton blue
in lactophenol. The collections are held at NZFRI-M (New Zealand Forest Research
Institute, Mycological Herbarium, Rotorua, New Zealand). Additional collections examined
(one each) were from the herbaria at Martin-Luther-Universität, Halle, Germany (HAL),
and CABI Bioscience, United Kingdom (IMI).
For each specimen examined, the location is followed by a two-letter code identifying the
geographic region (Crosby et al. 1976) in which it was collected (Table 1). Further
information on the distribution of the fungi, and the incidence and severity of disease caused
by each species, is held in the New Zealand Forest Research Forest Health Database (Forest
Research Institute 1990).
TABLE 1–Codes identifying the biological regions from which the specimens originated
––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
AK Auckland
BP Bay of Plenty
BR Buller
MC mid-Canterbury
ND Northland
NN Nelson
SL Southland
TO Taupo
WI Wanganui
WA Wairarapa
––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
Braun & Dick—Leaf spot diseases of eucalypts 223
DESCRIPTIONS OF SPECIES
1. Pseudocercospora acerosa U.Braun & M.Dick sp. nov. (Fig. 1)
Etym.: “acerosus”, derived from the broadly acicular conidia.
Differt a P. eucalyptorum conidiophoris longioribus et latioribus, saepe ramosis, conidiis
late acicularibus, basibus latioribus.
Holotype: on Eucalyptus baxteri (Benth.) J. M. Black (Myrtaceae), New Zealand,
Christchurch, Hagley Park (MC), 26 Sept. 2001, P.M.Bradbury (NZFRI-M 4580).
FIG. 1–Pseudocercospora acerosa. (1) Conidia, (2) germinating conidium (left) and
anastomosing conidia (right), (3) fasciculate conidiophores, (4) conidiophore, (5)
superficial hyphae with solitary conidiophores, (6) anastomosing superficial hyphae.
Bar = 20 µm.
224 New Zealand Journal of Forestry Science 32(2)
Leaf spots amphigenous, subcircular to angular-irregular, 1–10 mm diam. or confluent,
pale to medium dark brown, dingy greyish brown, margin indefinite or with a narrow darker
border or marginal line, reddish brown to dark brown, margin or sometimes entire spots
somewhat raised. Caespituli amphigenous, mostly hypophyllous, punctiform to effuse, dark
greyish brown. Primary mycelium internal; secondary mycelium external, sparingly to well
developed, superficial; hyphae septate, branched, 1.5–5 µm wide, subhyaline to pale
olivaceous or olivaceous-brown, smooth (and also conidia) occasionally anastomosing.
Stromata absent or 10–60 µm diam., substomatal, occasionally intraepidermal, olivaceous-
brown, composed of swollen hyphal cells, 2–8 µm diam., thick-walled. Conidiophores in
small to moderately large loose fascicles, arising from internal hyphae or stromata, or
solitary, arising from superficial hyphae, lateral or terminal, erect to decumbent, cylindrical-
filiform to geniculate-sinuous, unbranched or often branched, 20–220 × 3–8 µm, at the base
sometimes up to 11 µm wide, continuous to pluriseptate throughout, occasionally constricted
at the septa, pale olivaceous, olivaceous-brown, yellowish to medium brown, smooth, wall
thin to somewhat thickened, above all in the lower half and near the base; conidiogenous cells
integrated, terminal, 10–40 µm long, conidiogenous loci inconspicuous, occasionally
subdenticulate. Conidia solitary, 40–180 × (2.5–)3–5.5(–6) µm, short conidia subcylindrical,
rarely obclavate, longer conidia broadly acicular (i.e., gradually attenuated from a truncate
base towards the apex), 4- to 15-septate, subhyaline, pale olivaceous to olivaceous-brown,
smooth, wall thin to slightly thickened, apex obtuse in short conidia and obtuse to subacute
in longer conidia, base truncate, rarely slightly narrowed at the very base (short obconically
truncate), (2.5–)3–4(–5) µm wide, hila unthickened, non-pigmented. Conidia often
germinating, forming long narrow germ tubes that may develop into thin superficial
mycelium, or conidia forming secondary conidiophores (microcyclic conidiogenesis).
Distribution and host range: on Eucalyptus baxteri and E. nitens (Deane & Maiden)
Maiden. South Island, New Zealand.
Material examined: On E. baxteri, Christchurch, Hagley Park (MC), 26 Sep. 2001,
P.M.Bradbury (holotype). On E. nitens, Waikuku (MC), 22 Jun. 1999, P.M.Bradbury
(NZFRI-M 4003); Nelson, Golden Downs Forest (NN), 12 Apr. 1999, H.M.McKenzie
(NZFRI-M 3951); Fortification Block (SL), 19 Nov. 2001, M.Dick (NZFRI-M 4618).
Pseudocercospora acerosa sp. nov. is close to P. eucalyptorum and has often been
confused with this species, but differs in having much-longer broadly acicular conidia with
wider hila and much-longer broader frequently branched conidiophores. The general habit
of P. acerosa resembles P. crousii U.Braun & M.Dick, described in this paper, but the latter
species can be easily distinguished by its obclavate conidia with distinctly obconically
truncate bases.
2. Pseudocercospora crousii U.Braun & M.Dick sp. nov. (Fig. 2)
Etym.: P.W.Crous, South African mycologist and phytopathologist, author of a monograph
of Mycosphaerella species and their anamorphs on eucalypts.
Differt a P. paraguayensis conidiis latioribus, conidiophoris longioribus, per stoma
emergentibus et a P. eucalyptorum et P. acerosa conidiis obclavatis vel obclavatis-cylindraceis.
Holotype: on Eucalyptus regnans F.Muell (Myrtaceae), New Zealand, Whakarewarewa
Forest (BP), 18 Sep. 2001, M.Dick (NZFRI-M 4550).
Braun & Dick—Leaf spot diseases of eucalypts 225
FIG. 2–Pseudocercospora crousii. (1) Conidia, (2) fasciculate conidiophores, (3) superficial
hyphae with solitary conidiophores. Bar = 20 µm.
Leaf spots amphigenous, subcircular to angular-irregular, sometimes oblong, 1–15 mm
diam., sometimes confluent and larger, brown, reddish brown, later greyish brown to greyish
white, with a darker narrow margin or marginal line, often somewhat raised, brown to
purplish violet, finally often blackish. Caespituli amphigenous, mostly hypophyllous,
punctiform to subeffuse, brown, greyish brown, often not very conspicuous. Primary
mycelium internal; secondary mycelium external, superficial; septate, branched, 1–4.5 µm
wide, subhyaline to pale olivaceous, smooth, thin-walled, hyphae occasionally anastomosing.
Stromata lacking or small, 10–30 µm diam., substomatal, olivaceous-brown. Conidiophores
in small to moderately large fascicles, loose to moderately dense, arising from internal
hyphae or substomatal stromata, emerging through stomata, or conidiophores solitary,
arising from creeping hyphae, lateral, occasionally terminal, erect, straight, subcylindrical
to geniculate-sinuous, unbranched or often branched, 5–100 × 2.5–5.5 µm, aseptate to
pluriseptate throughout, wall thin to slightly thickened, smooth, conidiophores occasionally
reduced to conidiogenous cells, but conidiogenous cells usually integrated, terminal,
226 New Zealand Journal of Forestry Science 32(2)
5–30 µm long, conidiogenous loci inconspicuous. Conidia solitary, obclavate or obclavate-
cylindrical, short conidia sometimes cylindrical, (20–)35–115(–140) × 3–5 µm, 4- to
10-septate, subhyaline to pale olivaceous or olivaceous-brown, smooth or almost so, wall
thin to slightly thickened, apex obtuse to subacute, base obconically truncate, (1–)1.5–2
(–3) µm diam., hila unthickened, non-pigmented.
Distribution and host range: on Eucalyptus delegatensis R.T.Baker, E. dendromorpha
(Blakely) L.A.S.Johnson & Blaxell, E. fastigata Deane & Maiden, E. muelleriana Howitt,
E. obliqua L’Herit, E. oreades R.T.Baker, E. pilularis J.Sm., E. regnans, E. regnans ×
E.obliqua , and E. stenostoma L.A.S.Johnson & Blaxell. New Zealand. Entries in the Forest
Health Database (FHDB) document that E. regnans is the worst affected of these host
species, with severe defoliation often attributed to infection by Pseudocercospora sp.
Although all collections examined were from the North Island of New Zealand, the FHDB
records indicate that this fungus is also found in the northern part of the South Island.
Material examined (all collections from New Zealand): On E. delegatensis, Pouakani
(TO), 1 May 1981, R.M.J.McKenzie (NZFRI-M 2354); Lismore Forest (WI), 2 Sep. 1981,
M.Stoodley (NZFRI-M 2352). On E. dendromorpha, Mamaku, Jeff Rd. (BP), 29 Sep. 1988,
F.Crockett and M.Dick (NZFRI-M 3275). On E. fastigata, Pouakani North (TO), 17 Jun.
1986, R.M.J.McKenzie (NZFRI-M 3147). On E. muelleriana, Omatoroa (BP), 6 Jun. 1997,
E.Hay (NZFRI-M 3778). On E. obliqua, Rotoehu Forest (BP), 1 Jul. 1982, A.Zandvoort
(NZFRI-M 2355). On E.oreades, Rotoehu Forest (BP), 23 Jul. 1982, M.Dick (NZFRI-M
2357). On E. pilularis, Auckland, Remuera Golf Course (AK), 12 Aug. 1999, T.M.Withers
(NZFRI-M 4006); Auckland, Remuera, Abbotts Way (AK), 20 Dec. 1999, T.M.Withers
(NZFRI-M 4061); Paengaroa, Allport Rd (BP), 30 Jun. 2000, J.Pascoe (NZFRI-M 3203). On
E. regnans, Whakarewarewa Forest (BP), 18 Sep. 2001, M.Dick (holotype); Rotoehu Forest
(BP), 1 Apr. 1981, A.Zandvoort (NZFRI-M 2353). On E. regnans × E. obliqua, Rotoehu
Forest (BP), 23 Jul. 1982, M.Dick (NZFRI-M 2356). On E. stenostoma, Kaingaroa Forest
(TO), 11 Jan. 1988, D.Hayes (NZFRI-M 3237).
This species is close to P. paraguayensis (T.Kobay.) Crous, but differs in having wider
conidia and much longer conidiophores emerging through stomata. Pseudocercospora
eucalyptorum and P. acerosa are also similar, but they have cylindrical and broadly acicular
conidia with much wider, non-attenuated, truncate bases.
3. Pseudocercospora eucalyptorum Crous, M.J.Wingf., Marasas & B.Sutton (Fig. 3)
Mycological Research 93: 394 (1989)
Ref.: Crous (1998: 132–134, Fig. 118, 119, 130).
Leaf spots amphigenous, subcircular to usually angular-irregular, 0.5–7 mm diam., often
confluent, at first often yellowish, later pale to dark brown, purplish violet, finally usually
greyish brown to dingy grey, margin indefinite or with a darker border, brown or red-purple
to purplish violet, occasionally somewhat raised. Caespituli amphigenous, punctiform to
subeffuse, greyish brown to dingy grey. Primary mycelium internal; secondary mycelium
external, superficial; hyphae creeping, emerging through stomata, sparingly branched,
septate, 1.5–3 µm wide, subhyaline to pale olivaceous or olivaceous-brown, smooth, thin-
walled. Stromata lacking to well-developed, 10–200 µm diam., up to 50 µm deep, substomatal,
somewhat erumpent, olivaceous-brown. Conidiophores in small, loose to large, dense
Braun & Dick—Leaf spot diseases of eucalypts 227
FIG. 3–Pseudocercospora eucalyptorum. (1) Conidia, (2) fasciculate conidiophores,
(3)conidiophores, (4) superficial hyphae with solitary conidiophores. Bar = 20 µm.
fascicles, arising from internal hyphae or stromata, emerging through stomata, large
fascicles often almost sporodochial, or solitary, arising from creeping hyphae, lateral, rarely
terminal, erect, straight, subcylindrical to geniculate-sinuous, unbranched or occasionally
branched, 10–60 × 2.5–6 µm, 0- to 3-septate, subhyaline to olivaceous or light brown, wall
thin to slightly thickened, smooth to faintly rough-walled, conidiophores reduced to
conidiogenous cells or conidiogenous cells integrated, terminal, 10–25 µm long, conidiogenous
loci inconspicuous or subdenticulate, truncate, but wall unthickened and non-pigmented.
Conidia solitary, cylindrical or subcylindrical, 15–70 × (2–)3–4(–4.5) µm (in vitro up
to100 µm, and up to 10-septate), 1- to 7(8)-septate, subhyaline to pale olivaceous or
olivaceous-brown, smooth to faintly rough-walled, wall thin to slightly thickened, apex
obtuse, rounded, base truncate or only slightly obconically truncate at the very base,
(1.5–)2–3 µm wide, hila unthickened, non-pigmented.
Material examined (all collections from New Zealand): On E. nitens, Rotorua, Longmile
Rd (BP), 5 May 1997, collector unknown (NZFRI-M 3783); Kinleith Forest (TO), Oct. 1981,
R.M.J.MacKenzie (NZFRI-M 2350); Kinleith Forest, Tram Rd (BP), 6 May 1985,
R.M.J.MacKenzie (NZFRI-M 3066); Victoria Forest (BR), 24 Mar. 2000, B.H.Doherty
(NZFRI-M 4170); Kinleith Forest, Toatoa Rd. (TO), 8 Nov. 1983, R.M.J.MacKenzie
(NZFRI-M 2358); Rotoehu Forest (BP), 27 Oct. 1981, A.Zandvoort (NZFRI-M 2351). On
E. scoparia Maiden, Palmerston North, Victoria Esplanade (WI), 12 Jan. 1998, B.J.Rogan
(NZFRI-M 3802). On Eucalyptus sp., Whangarei, Okara Park (ND), 10 Mar. 1980,
228 New Zealand Journal of Forestry Science 32(2)
D.Kershaw (NZFRI-M 2349); Auckland, Mt Albert, Owairaka Avenue (AK), 18 Jul. 2001,
C.F.Hill (HAL 1739); Gladstone (WA), 12 Nov. 1974, J.E.Sheridan (IMI 189775d).
Pseudocercospora eucalyptorum is common throughout the North Island (only one of the
specimens examined was from the South Island) of New Zealand, particularly on E. nitens.
Eucalyptus nitens, which is also the type host of this species, has been widely planted in New
Zealand to provide a source of short fibre for the pulp and paper industry.
4. Pseudocercospora pseudobasitruncata U.Braun & M.Dick sp. nov. (Fig. 4)
Etym.: “pseudo-” and “basitruncata”, resembling the species P. basitruncata characterised
by having conidia with truncate base.
Differt a P. basitruncata, P. cubae et P. natalensis conidiis longioribus, 4–7 µm latis.
Holotype: on Eucalyptus nitens (Myrtaceae), New Zealand, Kaingaroa Forest (TO), 11 Jul.
1984, D.J.Slater-Hayes (NZFRI-M 2068).
Leaf spots amphigenous, subcircular to angular-irregular, 1–10 mm diam. or confluent
and larger, pale to dark brown or blackish brown, later pale greyish brown to dingy grey,
margin narrow, somewhat raised, reddish-purplish or pale to dark brown or with a raised
marginal line and diffuse reddish-purplish halo. Caespituli amphigenous, punctiform,
occasionally subeffuse, brownish, inconspicuous. Primary mycelium internal; secondary
mycelium absent or occasionally with a few superficial hyphae, sparingly branched, septate,
smooth, pale olivaceous, 2–3 µm wide, emerging through stomata, but without solitary
conidiophores. Stromata lacking or small, 10–35 µm diam., substomatal, brown.
Conidiophores in small to moderately large fascicles, usually 3–20, loose, emerging through
stomata, erect, straight, subcylindrical to somewhat geniculate-sinuous, unbranched, 10–70
FIG. 4–Pseudocercospora pseudobasitruncata. (1) Conidia, (2) fasciculate conidiophores, (3)
conidiophores, (4) superficial hypha. Bar = 20 µm.
Braun & Dick—Leaf spot diseases of eucalypts 229
× 4–7 µm, 0- to 4-septate, wall thin to somewhat thickened, pale to medium dark olivaceous
or olivaceous-brown, smooth to somewhat rough-walled; conidiogenous cells integrated,
terminal, 10–30 µm long, proliferation usually percurrent, with 1–3 conspicuous annellations,
occasionally sympodial, conidiogenous loci flat, truncate, 3–5 µm wide, unthickened, non-
pigmented. Conidia solitary, most conidia broadly acicular (i.e., gradually attenuated from
a truncate base towards the apex), some shorter conidia obclavate-cylindrical, 40–100 × 4–
7 µm, 3- to 10-septate, pale olivaceous-brown, apex obtuse, base truncate, occasionally short
obconically truncate, 4–5 µm wide, hila unthickened, non-pigmented.
Material examined: only known from the type collection in the central North island.
Pseudocercospora pseudobasitruncata resembles P. basitruncata Crous, described on
Eucalyptus sp. from Colombia, but differs from it as well as from P. cubae Crous and P.
natalensis Crous & T. Coutinho, two additional species with conspicuous annellations, in
having much longer and above all wider conidia.
KEY TO THE SPECIES OF PSEUDOCERCOSPORA OCCURRING ON
EUCALYPTUS IN NEW ZEALAND
1. Superficial mycelium lacking or with only a few creeping hyphae; conidiophores
in small to moderately large fascicles, mostly unilocal, conidiogenous cells mostly
subcylindrical, proliferation usually percurrent, with 1–3 conspicuous annellations;
conidia broadly acicular, gradually attenuated from a truncate base towards the
apex, conidia cylindrical-obclavate, 40–100 × 4–7 µm, base truncate, occasionally
obconical
.................................................................................................. P. pseudobasitruncata
1. Superficial mycelium usually well-developed; conidiophores fasciculate and
often also solitary, arising from creeping hyphae, lateral; conidiogenous cells
often geniculate-sinuous, proliferation sympodial, rarely mixed with a few
percurrent proliferations and inconspicuous annellations; conidia (2–)3–5(–6) µm
wide
.................................................................................................................................... 2
2. Conidia obclavate or obclavate-cylindrical, base attenuated, distinctly obconically
truncate
.......................................................................................................................P. crousii
2. Conidia cylindrical, subcylindrical or broadly acicular, base not attenuated,
truncate
.................................................................................................................................... 3
3. Conidia cylindrical or subcylindrical, 15–70(–80) × (2–)3–4(–4.5) µm, base
truncate, occasionally slightly obconically truncate, (1.5–)2–3 µm wide
............................................................................................................P. eucalyptorum
3. Short conidia cylindrical, longer conidia broadly acicular, gradually attenuated
from a truncate base towards the apex, 40–180 × (2.5–)3–5.5(–6) µm, base
(2.5–)3–4(–5) µm wide
..................................................................................................................... P. acerosa
230 New Zealand Journal of Forestry Science 32(2)
Three different species of cercosporoid hyphomycetes are found on E. nitens in New
Zealand, viz, Pseudocercospora acerosa, P. eucalyptorum, and P. pseudobasitruncata,
whereas each of the other 12 eucalypt hosts reported here supports only one species of
Pseudocercospora. Although Eucalyptus is an Australian genus, most cercosporoid species
infecting the genus have been described from other parts of the world and have not yet been
collected in Australia. Based on the general assumption of a close co-evolution between
hosts and their pathogenic fungi, it can be supposed that Mycosphaerella spp. and their
anamorphs originate from Australia, but little is known about these fungi on eucalypts in their
natural habitats. Eucalypts have been cultivated for less than 200 years, more than 90% of
the plantation forests have been established since 1955 and about half in the last two decades
(Turnbull 1991), which is a period much too short for the evolution of “new species” outside
Australia. Crous & Wingfield (1997) speculated that pathogens of some other hosts of the
Myrtaceae could have adapted to eucalypts, but this assumption could not be confirmed in
detailed examinations carried out by Crous (1999).
It is probable that additional species of Pseudocercospora may occur in New Zealand.
Therefore, it is deemed useful to provide a revised general key, based on the key by Crous
(1998), supplemented by the new species described in the present paper.
REVISED KEY TO THE SPECIES OF PSEUDOCERCOSPORA ON
EUCALYPTUS FOLIAGE WORLDWIDE
1. Conidiophores fasciculate, usually subcylindrical and unilocal, determinate or
percurrently proliferating, with 1–3 conspicuous annellations; conidia broadly
acicular (gradually tapering from a truncate base towards the apex), short conidia
subcylindrical-obclavate, 40–100 × 4–7 µm, base 4–5 µm wide; on Eucalyptus
nitens; New Zealand
.................................................................. P. pseudobasitruncata U.Braun & M.Dick
1. Conidiophores fasciculate as well as solitary, arising from creeping hyphae, or
conidial shape different, or conidial base obconically truncate and usually < 4µm
wide
.................................................................................................................................... 2
2. Conidia distinctly cylindrical or acicular (gradually tapering from base to apex),
base truncate (or only slightly attenuated at the very base)
.................................................................................................................................... 3
2. Conidia obclavate to obclavate-subcylindrical, base distinctly attenuated (short to
long obconically truncate)
.................................................................................................................................. 11
3. Conidia consistently cylindrical or subcylindrical, not attenuated towards the apex
.................................................................................................................................... 4
3. At least long conidia distinctly acicular, base truncate, gradually tapering towards
an obtuse or subacute apex
.................................................................................................................................... 6
Braun & Dick—Leaf spot diseases of eucalypts 231
4. Conidiophores consistently solitary, arising from creeping superficial hyphae as
short lateral projections; conidia narrow, 35–100 × 2–3 µm, 3- to 11-septate; on
E. urophylla S.T.Blake; Indonesia
..........................................................................................P. gracilis Crous & Alfenas
4. Conidiophores solitary, arising from creeping hyphae, as well as fasciculate or
even forming sporodochial conidiomata
.................................................................................................................................... 5
5. Leaf spots more or less angular-irregular; conidia 15–70(–80) × 2–4.5 µm, 1- to
7-septate (in vivo), subhyaline to pale olivaceous or olivaceous-brown, smooth to
faintly rough-walled, often with irregular swellings; on a wide range of eucalypts,
widespread
........................................................................................ P. eucalyptorum Crous et al.
5. Leaf spots subcircular; conidia longer, (45–)70–80(–110) × (2.5–)3–3.5 µm, 3- to
9-septate, darker, light to medium brown, verruculose, swellings lacking; on
E.robusta Smith; Malaysia
....................................................................................P. robusta Crous & M.J.Wingf.
6. Conidia 40–180 × (2.5–)3–5.5(–6) µm, 4- to 15-septate, base (2.5–)3–4(–5) µm
wide; conidiophores in loose, divergent fascicles, often decumbent, or solitary,
long, 20–220 × 3–8 µm, pluriseptate throughout; on E. baxteri and E. nitens; New
Zealand
..................................................................................... P. acerosa U.Braun & M.Dick
6. Conidia narrower, 2–3(–4) µm, base also narrower, 1.5–3 µm; conidiophores in
denser fascicles, arising from stromata, erect, shorter, 10–60 µm long
.................................................................................................................................... 7
7. Conidia relatively short, (20–)30–40(–50) µm, 0- to 3-septate, olivaceous; on
Eucalyptus sp.; Cuba
..............................................................................................................P. cubae Crous
7. Conidia longer, exceeding 50 µm, pluriseptate
.................................................................................................................................... 8
8. Superficial secondary mycelium lacking; conidiophores in small fascicles, not
arising from stromata; conidia (40–)60–100 × 2-3 µm, (4-)6- to 10(12)-septate; on
E. citriodora Hooker; Australia
............................................................................................P. eucalyptigena U. Braun
8. Superficial secondary mycelium with solitary conidiophores present or
conidiophores in large fascicles arising from well-developed stromata and/or
conidia shorter
.................................................................................................................................... 9
9. Caespituli grey on leaves; with irregular annellations on conidiogenous cells;
conidia olivaceous to medium brown, (25–)45–70(–100) × 2.5–3(–4) µm; on
E.grandis Maiden and Eucalyptus sp.; Colombia
................................................................................................... P. basitruncata Crous
9. Caespituli brown on leaves; annellations inconspicuous and aggregated on
conidiogenous cells when present
.................................................................................................................................. 10
232 New Zealand Journal of Forestry Science 32(2)
10. Leaf spots angular to subcircular, light to dark brown, 1–9 mm diam.; annellations
fine, aggregated at apices of conidiogenous cells when present; conidia olivaceous
to light brown, smooth or only faintly rough-walled, (30–)50–85(–110) × (2–)2.5–
3(–3.5) µm in vivo (in vitro often longer); on E. nitens; South Africa
................................................................................P. natalensis Crous & T.Coutinho
10. Leaf spots subcircular, light brown to grey, 3–15 mm diam.; annellations lacking;
conidia darker, light to medium brown, verruculose, (35–)45–75(–85) × 2.5–3 µm
(in vivo), in vitro up to 200 × 1.5–2 µm; on E. saligna Smith; South Africa
.................................................................... P. irregulariramosa Crous & M.J.Wingf.
(Mycosphaerella irregulariramosa Crous & M.J.Wingf.)
11. Conidia with irregular swellings, medium brown, becoming olivaceous near the
apex, verruculose, 1- to 7-septate, (17–)45–65(–90) × 3.5–4(–5) µm, hila 1.5–
2 µm wide; conidiogenous cells verruculose, proliferation sympodial and percurrent
with irregular annellations; on Eucalyptus sp.; Peru
...................................................................................................... P. irregularis Crous
11. Conidia uniformly obclavate, without swellings
.................................................................................................................................. 12
12. Conidiogenous loci and conidia with a minute thickening along the rim
(Paracercospora-like), lateral branchlets frequently present, conidia (35–)50–
70(–80) × 2(–3) µm; on E. camaldulensis Denh. and E. pellita F.Muell.; Thailand
...................................................................................................P. basiramifera Crous
12. Conidiogenous loci and hila completely unthickened
.................................................................................................................................. 13
13. Leaf spots lacking; conidiophores reduced to very short denticle-like conidiogenous
cells, solitary, arising from creeping hyphae, lateral, 3–10 × 2–3.5 µm; conidia
(25–)40–90(–150) µm long; on Eucalyptus sp.; Indonesia
...............................................................................P. heimioides Crous & M.J.Wingf.
13. Conidiophores much longer
.................................................................................................................................. 14
14. Conidiogenous cells distinctly denticulate
.................................................................................................................................. 15
14. Conidiogenous cells non-denticulate
.................................................................................................................................. 16
15. Lesions irregular, varying from specks to angular or subcircular spots, 1–8 mm
diam., margin red-purple; conidia olivaceous, 1- to 5-septate, (25–)40–50(–70) ×
2–2.5(–3) µm; on E. globulus Labill. and Eucalyptus sp.; Dominican Rep. and
Japan
..................................................................................................... P. denticulata Crous
15. Lesions irregular, elongated, 5–15 mm diam.; conidia olivaceous-brown,
pluriseptate, 55–300 × 2.5–3 µm; on E. obliqua, E. urophylla, Eucalyptus sp.;
Indonesia, Madagascar
.....................................P. heimii Crous (Mycosphaerella heimii Bouriquet ex Crous)
Braun & Dick—Leaf spot diseases of eucalypts 233
16. Conidiophores medium brown, almost smooth to verruculose, thick-walled, in
loose fascicles, 30–120 × 3–6 µm; conidia light to medium brown, smooth to
verruculose, 0- to 8-septate, (35–)45–70(–80) × (3–)3.5–4(–4.5) µm; mycelium
only internal; on E. deglupta Blakely; Malaysia, Papua-New Guinea
......................................................................................................... P. deglupta Crous
16. Conidiophores shorter than 60 µm or with secondary superficial mycelium and
solitary conidiophores
.................................................................................................................................. 17
17. Conidiophores reduced to conidiogenous cells, up to 20 µm long
.................................................................................................................................. 18
17. Conidiophores mostly septate, doliiform to ampulliform when non-septate
.................................................................................................................................. 19
18. Conidiophores occurring on spermogonia; 5–20 × 2.5–4 µm; conidia 28–65 ×
2–3 µm; leaf spots subcircular to irregular, 10–20 mm diam., also associated with
tip die-back; on E. grandis × E. saligna; South Africa
................................................................. P. epispermogoniana Crous & M.J. Wingf.
18. Not on spermogonia; leaf spots subcircular, 2–10 mm diam.; conidiophores and
conidia only formed in vitro, conidiophores 2–7 × 1.5–2.5 µm, conidia 50–200 ×
2–3 µm; on E. bicostata Labill. and E. grandis × E. camaldulensis; South Africa
...............................................................................P. crystallina Crous & M.J.Wingf.
(Mycosphaerella crystallina Crous & M.J.Wingf.)
19. Conidiophores in loose fascicles, emerging through stomata, or solitary, arising
from superficial hyphae, 5–100 µm long, aseptate to pluriseptate throughout, often
branched; conidia (20–)35–115(–140) × 3–5 µm, (2-)3- to 12(15)-septate; on a
wide range of Eucalyptus spp.; New Zealand
.......................................................................................P. crousii U.Braun & M.Dick
19. Conidiophores solitary or fasciculate, at least partly erumpent through the cuticle,
erect, shorter, 10–30 µm long, 0- to 2-septate; conidia narrower (25–)30–70(–80)
× (1.5–)2–3(–3.5) µm, 1- to 7(8)-septate
.................................................................................................................................. 20
20. Leaf spots angular, confined by leaf veins, light to medium brown, 1–4 mm diam.,
border hardly or slightly raised, margin thin, indefinite or reddish; conidiophores
cylindrical, 0- to 2-septate, 10–30 × 2–4 µm; conidia (1-)3- to 7(8)-septate,
(25–)30–70(–80) × (1.5–)2–3(–3.5) µm, subhyaline to pale olivaceous; on
E.citriodora, E. globulus, E. nitens, Eucalyptus sp.; Brazil, India
*
, Israel, Paraguay,
Taiwan, Vanuatu
*
............................................................................. P. paraguayensis (T.Kobay.) Crous
* Bagaynarayana et al. (1995) and Braun et al. (1999) recorded Pseudocercospora eucalyptorum on
Eucalyptus sp. from India and Vanuatu, respectively. In these papers, P.eucalypti Goh & W.H.Hsieh
(Hsieh & Goh 1990) was cited as a synonym of P.eucalyptorum . However, Crous (1998) pointed
out that P. eucalypti, with narrowly obclavate conidia, was a synonym of P. paraguayensis, and that
P.eucalyptorum with its consistently cylindrical conidia was a separate species. The collections
from India and Vanuatu have narrow obclavate conidia and belong, indeed, to P. eucalypti (syn.
P.paraguayensis ). The records of “P. eucalyptorum” from these two locations must therefore be
cancelled and corrected to P. paraguayensis.
234 New Zealand Journal of Forestry Science 32(2)
20. Leaf spots subcircular to irregular, 1–15 mm diam., dark brown, border raised,
margin indefinite; conidiophores 0- to 1-septate, doliiform to ampulliform, 12–25
× 2.5–4.5 µm; conidia 1- to 5-septate, (25–)30–45(–60) × 2.5–3(–3.5) µm; on
E.urophylla ; Colombia
........................................................................... P. columbiensis Crous & M.J.Wingf.
(Mycosphaerella columbiensis Crous & M.J.Wingf.)
ACKNOWLEDGMENTS
We gratefully acknowledge the assistance of Chris Ecroyd and Paul Bradbury in checking host
records, both with follow-up field visits and in the Botanical Herbarium.
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