Forest Pathology in New Zealand No. 14

(Second Edition 2010)

Rust fungi in native forests

I.A. Hood

(Revised by I.A. Hood)

Introduction

Rusts make up a large group of fungi that parasitise a wide range of plants. Each

rust is usually able to infect only a limited number of hosts, and may produce

symptoms of swelling, distortion, or spotting on stems, twigs, or leaves.

Generally, the life cycle is complex: each rust alternates between two different

host species in a regular fashion, completing one cycle during a year. Five types

of spore are produced successively during a cycle. These stages are known,

respectively, as pycniospores (produced in pycnia), aeciospores (in aecia),

urediniospores (in uredinia), teliospores (in telia), and basidiospores (from

basidia). In New Zealand, however, many of the native rusts complete their life

cycles on one host species, and some do not produce all of the spore stages.

Rust of Aristotelia (wineberry)

Causal organism

Aecidium milleri Cunningham

Type of injury

Leaf spotting.

Diagnostic features

� lrregular, pale yellow spots, up to 4 mm long, coincident on both surfaces

of green leaves.

� Tiny (not exceeding 0.25 mm diameter), cup-shaped pustules (aecia)

distributed singly or in groups on lower leaf surfaces (Fig. 1).

Hosts

Aristotelia fruticosa; A. serrata; A. xfruserrata.

Distribution

South Island and the southern half of the North Island.

Disease development

The alternate host of this rust has yet to be identified.

Economic importance

Wineberry frequently regenerates densely and may become a weed species in

pine plantations established on sites cleared of indigenous forest. There is no

evidence that A. milleri provides any biological control of its host on such sites.

Control

Not considered necessary.

Fig. 1 – Cup-shaped pustules of Aecidium

milleri on leaf of Aristotelia fruticosa.

Fig. 2 - Cup-shaped pustules of Aecidium

otagense on swollen stem of Clematis paniculata.

Rusts of Clematis

Causal organisms

Aecidium otagense Lindsay

Puccinia alboclava Baylis

Puccinia clavata Sydow

Uredo puawhananga Baylis

Type of injury

Aecidium otagense induces distortions of stems, petioles, leaves, or flowers. The

other fungi cause minor leaf spotting.

Diagnostic features

� Aecidium otagense: Inflated, distorted swellings up to 16 cm long on

stems, petioles, leaves, sepals; numerous small, orange cups (aecia),

up to 1 mm in diameter, densely scattered over affected areas (Fig. 2).

� Puccinia alboclava and P. clavata: Circular spots up to 2 mm in

diameter (telia), possibly accompanied by slight distortions, on lower or

both surfaces of green leaves; spots black (P. clavata) (Fig. 3) or pale

grey to buff (P. alboclava).

� Uredo puawhananga: Small, yellow-orange pustules (uredinia), up to 3 mm in diameter, on lower surfaces of green leaves (Fig. 4).

Fig. 3 – Black spots of Puccinia clavata on

leaf of Clematis parviflora.

Fig. 4 – Yellow-orange pustules of Uredo

puawhananga on leaf of Clematis paniculata.

Hosts

Individual host Fungal parasite

Clematis afoliata

C. cunninghamii

*C. flammula

C. foetida

C. forsteri

C. marata

*C. montana

C. paniculata

*C. thunbergii

*C. vitalba

*Introduced host species

Aecidium otagense

Puccinia clavata; Uredo puawhananga

U. puawhananga

A. otagense; P. clavata; U. puawhananga

A. otagense; P. clavata; U. puawhananga

A. otagense

U. puawhananga

A. otagense; Puccinia alboclava; U. puawhananga

U. puawhananga

U. puawhananga

Distribution

Aecidium otagense, P. clavata, and U. puawhananga are each found throughout

New Zealand. Puccinia alboclava is known in Otago and the central North Island.

Disease development

Puccinia clavata, P. alboclava, and U. puawhananga each complete a full life

cycle, with a reduced number of spore stages, on only one host. Although

possibly once of common ancestry, they are now considered to be distinct

species. Two host-specific races of P. clavata are known, one occurring on

C. foetida and the other on either C. paniculata or C. forsteri. Other races may

also exist. The spots induced by this fungus on the undersides of leaves

eventually extend right through to the upper surfaces.

Aecidium otagense persists as a perennial infection in stem tissue, regularly

producing aecia and microscopic pycnia. This rust is believed to require a second

host, as yet undiscovered, to complete its life cycle. Aecidium otagense may itself

be parasitised by another fungus, Tuberculina persicina, which gives to the

swollen stem areas a distinctive, violet, powdery appearance.

Economic importance

None of the Clematis rusts are economically important. Although

U. puawhananga attacks the noxious weed C. vitalba (old man's beard), it is

unlikely that infection levels will ever be sufficient to achieve biological control.

Control

Not considered necessary.

Rust of Coprosma

Causal organism

Puccinia coprosmae Cooke

Type of injury

Leaf spotting.

Diagnostic features

� Dark brown-to-black, circular leaf spots, up to 8 mm in diameter, on

lower or both surfaces of green leaves.

� Tiny (up to 1 mm in diameter), black, powdery pustules (telia) scattered

over spots on lower leaf surfaces (Fig. 5).

Fig. 5 – Dark spots with black pustules

on leaf of Coprosma lucida infected by

Puccinia coprosmae.

Hosts

Coprosma chathamica; C. dodonaeifolia; C. grandifolia; C. lucida;

C. macrocarpa; C. perpusilla; C. pumila; C. repens; C. robusta.

Distribution

Widespread throughout New Zealand.

Disease Development

Spots eventually penetrate through to upper leaf surfaces. The alternate host of

this rust has not yet been identified.

Economic importance

Of no significance.

Control

Not considered necessary.

Rust of Fuchsia

and Phyllocladus (tanekaha, toatoa)

Causal organism

Micronegeria fuchsiae P.E. Crane & R.S. Peterson

(= Uredo fuchsiae (Cooke) Hennings; = Caeoma peltatum Shaw & Shaw)

Type of injury

Leaves of Fuchsia are disfigured. On Phyllocladus, spotting of stems and

cladodes (flattened branchlet terminals, resembling and replacing leaves).

Diagnostic features

� On Fuchsia: small (up to 1 mm in diameter), orange-yellow, waxy pustules

(uredinia and telia) on both, but mostly the lower, surfaces of green or

dying leaves (Fig. 6).

� On Phyllocladus: bright, golden-orange, angular discolourations (aecia

and pycnia), up to 10 mm across, on cladodes or normal stems (Fig. 7).

Fig. 6 – Orange pustules of Micronegeria

fuchsiae on leaf of Fuchsia excorticata

Fig. 7 - Cladodes of Phyllocladus trichomanoides

disfigured by Micronegeria fuchsiae.

Hosts

F. excorticata; F. perscandens; *F. magellanica; Phyllocladus alpinus; P. toatoa;

P. trichomanoides.

*Naturalised host species. In urban areas in parts of the North Island an introduced rust fungus,

Pucciniastrum pustulatum (Pers.) Dietel produces similar symptoms leading to defoliation on

cultivated fuchsias and other plants in the same family (Onagraceae); a possibly separate race of

this species occurs on the indigenous F. procumbens and on native willow herbs (Epilobium spp.)

Distribution

Mikronegeria fuchsiae is present on native fuchsias throughout the country. On

Phyllocladus it has been found in the central North Island, Nelson and Westland.

Disease development

Microscopic pycnia (the sexual stage) are produced on the upper surfaces of the

orange infected zones on Phyllocladus cladodes mainly during autumn but also

in spring. Following fertilisation, aecial pustules erupt from the lower surfaces of

these discoloured zones during spring, releasing aeciospores that spread to and

infect the foliage of nearby fuchsia plants. Orange uredinial pustules appear on

infected fuchsia foliage during summer and autumn, discharging uredinospores

which spread infection to other fuchsias. These spores are apparently widely

dispersed, because infected plants can be found in places where there is no

Phyllocladus. Telial pustules develop within the tissues beneath the lower leaf

surface on the fuchsia host from mid-summer through to autumn. The teliospores

remain fixed but give rise to basidospores during periods of wet weather. These

are formed at the ends of slender microscopic stalks that protrude through the

leaf pores (stomata), forming spore clusters on the leaf surface. The cycle is

completed when basidiospores infect nearby Phyllocladus plants. Multiple

infections over a period of time give rise to different stages of development on the

same Phyllocladus individuals. Depending on location and climate, some

deciduous or semi-deciduous fuchsias may shed their infected leaves naturally

during winter.

.

Economic importance

Of no significance.

Control

Not considered necessary.

Rust of Hoheria and Plagianthus

(lacebarks and ribbonwoods)

Causal organism

Puccinia plagianthi McAlpine

Type of injury

Leaf spotting and stem distortion.

Diagnostic features

� Pale yellow, grey, or brown, irregular blotches, up to 4cm long, coincident

on both surfaces of green leaves or on distorted segments of stem.

� Dark brown, circular pustules (telia), less than 2 mm in diameter, mostly

on lower surfaces of leaves or on twigs. Pustules clustered on leaf

blotches, or scattered singly on green leaf surfaces (Fig. 8).

� Yellow spots (pycnia) on both surfaces of green leaves.

Fig. 8 – Brown pustules of Puccinia plagianthi

on leaf of Hoheria sp.

Fig. 9 - Pustules of Puccinia tiritea on leaf of

Muehlenbeckia australis.

Hosts

Hoheria angustifolia; H. glabrata; H. lyallii; H. populnea; Plagianthus divaricatus;

P. regius; P. regius subsp. chathamicus.

Distribution

Throughout New Zealand.

Disease development

There is probably no alternate host.

Economic importance

Of no significance.

Control

Not considered necessary.

Rust of Muehlenbeckia

Causal organism

Puccinia tiritea Cunningham

Type of injury

Leaf disfigurement.

Diagnostic features

� Tiny (up to 1 mm in diameter), light or dark brown pustules (uredinia or

telia) on lower surfaces of green leaves (Fig. 9).

� Tiny yellow spots (pycnia) on upper leaf surfaces.

Hosts: Muehlenbeckia australis; M. axillaris; M. axillaris × ephedroides;

M. complexa.

Distribution

Throughout New Zealand.

Disease development

The production of pycnia is followed by that of uredinia. Telia occur later, at the

beginning of winter. There is probably no alternate host.

Economic importance

Of no significance.

Control

Not considered necessary.

Rust of Myoporum (ngaio)

Causal organism

Aecidium myopori Cunningham

Type of injury

Stem swelling.

Diagnostic features

� Elongated, spindle-shaped swellings, up to 15 cm long, on living shoots or

on leaf or flower stalks; cankers may develop on swellings (Fig. 10).

� Tiny (up to 4 mm tall by 1 mm wide), yellow "tendrils" (aecia) scattered on

infected areas.

Notes: Symptoms may be confused with those caused by a caterpiIlar that tunnels within twigs.

However, this insect induces small round galls, up to 3 cm long, w do not bear yellow "tendrils".

Fig. 10 - Tiny, yellow tendrils scattered over the

swollen stem of Myoporum laetum infected by

Aecidium myopori.

Hosts

Myoporum laetum; *M. acuminatum.

* Introduced host species.

Distribution

Poverty Bay, Hawke's Bay, Wellington, and Marlborough.

Disease development

Persists in stems as a perennial infection with a regular production of

aeciospores. No alternate host is yet known for this rust.

Economic importance

Of no significance.

Control

Not considered necessary.

Rusts of Olearia

Causal organisms

Puccinia akiraho Cunningham

Puccinia atkinsonii Cunningham

Uredo tupare Cunningham

Type of injury

Spotting or distortion of leaves or shoots.

Diagnostic features

� Discoloured spots may occur on either or both surfaces of green leaves

(all three species).

� Distortions, up to 3 cm long, on leaves, petioles or shoots (P. atkinsonii).

� Tiny (up to 1 mm in diameter) black pustules (telia) on lower leaf surfaces

(P. atkinsonii).

� Tiny (up to l mm in diameter) pale yellow, orange or brown pustules

distributed singly or grouped on:

- twigs: aecia of P. atkinsonii (Fig. 11);

- upper leaf surfaces: aecia of P. akiraho (Fig. 12);

- lower leaf surfaces: telia of P. akiraho; aecia of P. atkinsonii;

uredinia of U. tupare.

Fig. 11 - Pustules of Puccinia atkinsonii on

twig of Olearia rani.

Fig. 12 – Leaf spot with pustules of Puccinia

akiraho on Olearia paniculata.

Hosts

Individual host

Olearia arborescens

O. avicenniaefolia

O. colensoi

O. colensoi var. grandis

O. furfuracea

Fungal parasite

Puccinia akiraho; Puccinia atkinsonii

P. akiraho

Uredo tupare

U. tupare

P. akiraho

O. ilicifolia

O. ilicifolia x lacunosa

O. lacunosa x arborescens

O. macrodonta

O. paniculata

O. rani

P. atkinsonii

P. atkinsonii

P. atkinsonii

P. atkinsonii

P. akiraho

P. atkinsonii

Notes: Additional rust fungi occur on species of Olearia that grow in habitats other than forests.

Distribution

All three species occur throughout New Zealand.

Disease development

Puccinia akiraho and P. atkinsonii are thought to complete their life cycles on one

host, and no alternate host is known for U. tupare. Microscopic pycnia are

produced by all three species followed by the formation of the other spore stages.

Economic importance

Of no significance.

Control

Not considered necessary.

Rust of Rubus (bush lawyers)

Causal organism

Hamaspora australis Cunningham

Type of injury

Leaf spotting.

Diagnostic features

� Small (up to 3 mm in diameter), brown spots coincident on both surfaces

of green needles.

� Bundles of thin, white, or pale, yellow threads (telia/basidia), up to 2 cm or

more long, arising from spots and lying across the lower leaf surfaces

(Fig. 13).

Fig. 13 - Brown spots of Hamaspora australis on

Rubus cissoides. Note the threads arising

from the spots.

Hosts

Rubus australis; R. cissoides; R. schmidelioides; R. schmidelioides var.

subpauperatus; R. schmidelioides × australis; R. squarrosus.

Notes: Hamaspora australis is confined to native species. The introduced Rubus species (e.g.,

blackberry, boysenberry) are attacked by other rust fungi, which do not produce teliospore

threads.

Distribution

Throughout New Zealand.

Disease development

Telial threads are produced throughout the summer period and, if not detached,

can persist on leaves for several seasons. Basidia and basidiospores are

produced from these threads. The alternate host for this rust is not yet known.

Economic importance

Of no significance.

Control

Not considered necessary.

Rust of Sophora (kowhai)

Causal organism

Uromyces edwardsiae Cunningham.

Type of injury

Stem and seed pod distortion.

Diagnostic features

� Swellings or distortions of living stems and twigs (Fig. 14); distortions with

tiny (up to 1 mm in diameter), orange-yellow, pustular tendrils (aecia).

� Irregular, wrinkled, pear-shaped, distortions of seed pods, each up to 4 cm

long, with a dark brown, powdery coat (Fig. 15).

Hosts

Sophora microphylla; S. prostrata; S. tetraptera.

Distribution

Throughout New Zealand.

Fig. 14 - Stem distortion and "brooming" of

Sophora sp. infected by Uromyces

edwardsiae.

Fig. 15 – Seedpod of Sophora microphylla

distorted by Uromyces edwardsiae.

Disease development

Persistent, perennial stem infections eventually produce tight knots of multiple

branching. Seed pods are attacked shortly after flowering, and distort as they

develop. Telia are produced on the distorted pod surfaces, which appear

powdery from the large numbers of dark teliospores. There is probably no

alternate host.

Economic importance

Of no significance.

Control

Not considered necessary.

BIBLIOGRAPHY

Baylis, G.T.S. 1954: Rust fungi on New Zealand clematis. Transactions of the

Royal Society of New Zealand 82: 633 - 7.

Crane, P.E.; Peterson, R.S. 2007: Micronegeria fuchsiae sp. nov., a rust fungus

on Fuchsia and Phyllocladus in New Zealand. New Zealand Journal of Botany

45: 707-713.

Cunningham, G.H. 1931: The rust fungi of New Zealand.

Dingley, J.M. 1969: Records of plant diseases in NewZealand. New Zealand

Department of Scientific and Industrial Research Bulletin 192.

Gadgil, P.D. 2005: Fungi on trees and shrubs in New Zealand. Fungi of New

Zealand Volume 4. Fungal Diversity Research Series 16: 1-437.

McKenzie, E.H.C. 1998: Rust fungi of New Zealand – an introduction, and list of

recorded species. New Zealand Journal of Botany 36: 233-271.

McNabb, R.F.R.; Laurenson, J.B. 1965: A rust of cultivated fuchsias. New

Zealand Journal of Agricultural Research 8: 336-339.

Pennycook, S.R. 1989: Plant diseases recorded in New Zealand. Plant Diseases

Division, DSIR, Auckland. 3 volumes.

Shaw, C.G. III 1976: Rust on Phyllocladus trichomanoides – the first recorded on

a member of the Podocarpaceae. Transactions of the British Mycological Society

67: 506 - 509.