FACTSHEET
Exotic Pest Alert: Potato wart
Plant Biosecurity Orange
Synchytrium endobioticum is an exotic plant
pest causing potato wart
This disease is a serious threat to Australia’s
potato industry
If symptoms are seen it must be reported
promptly to the Exotic Plant Pest Hotline
1800 084 881
Introduction
Potato wart is a soil-borne fungal disease of
potatoes. Potato wart mainly appears on
underground stolons and tubers. It does not occur
on the true roots of the potato plant.
Figure 1 Tubers with potato wart
The presence of the disease may not be noticed
until the potato tubers are harvested.
Potato wart is a plant disease and is not harmful to
people or animals.
Symptoms
On infected tubers the eyes develop into warty,
cauliflower-like swellings (Figure 1). Warts are
initially the same colour as the tuber and then turn
black as the fungus matures. Warts that become
exposed at or just above the soil line become
green (Figure 2).
Wart size varies from small growths to large multibranched swellings that may engulf the whole
tuber. Tubers may bear more than one warty
outgrowth (Figure 3). Tubers may become
disfigured or unrecognisable when they are
infected early in their development.
Figure 2 Potato wart growth exposed above the soil
Infected plants may develop general symptoms of
reduced vigour.
Symptoms associated with potato wart may appear
similar to some of the symptoms caused by
powdery scab, potato smut and ‘pseudo-wart’.
Proper identification and laboratory analysis is
required to confirm the presence of the potato wart
pathogen.
Figure 3 Potato plant with warts on tubers and stolons
June 2012, http://www.dpi.nsw.gov.au/factsheets for updates
Primefact 1203 first edition
Plant Biosecurity
Biology
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Potato wart mainly appears on underground
stolons and tubers. Under wet conditions, warts
may occur on stems.
practising on-farm biosecurity to prevent entry,
establishment and spread of pests and
diseases
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ensuring all staff and visitors are instructed in
and adhere to on-farm hygiene practices
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regularly monitoring your crop
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investigating sick plants
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keeping records
Potato wart symptoms can continue to develop
during storage. Dried out warts barely noticeable at
harvest may become increasingly obvious during
prolonged storage.
The potato wart fungus does not usually kill the
potato plant. If tuber sprouts are attacked by the
fungus shoots may fail to emerge from the soil.
Reporting
If you suspect symptoms of potato wart:
Survival
Call the Exotic Plant Pest Hotline on
Resting spores of potato wart are capable of
surviving in soil for over 30 years and at depths of
over 50 cm.
1800 084 881
Take photos not samples to minimise the risk
of spreading this disease
Visit the Plant Biosecurity website
Spread
Potato wart fungus has very limited capacity for
natural spread.
Long distance spread occurs through the
movement of infected soil and by infected
seed tubers.
Hosts
www.dpi.nsw.gov.au/biosecurity/plant
An exotic plant pest is a disease causing
organism or an invertebrate not present in
Australia and which threatens agricultural
production, forestry or native and amenity
plants.
Resources
The only cultivated host of potato wart is potatoes.
Department for Environment Food and Rural Affairs
Factsheet ‘Potato Wart Disease’
In Mexico wild potato species (Solanum) can
be infected.
Plant Health Australia (2005) Diagnostic Manual Potato
Wart Synchytrium endobioticum (Shilberzky) Percival
Under laboratory conditions a number of
solanaceous plants including tomato have been
artificially inoculated.
Franc, G. (2007) American Phytopathological Society
Features ‘Potato Wart’
Distribution
Potato wart originates in the Andean zone of South
America. It is thought to have been introduced on
breeding material to Europe after the Irish potato
famine of 1840-50.
Potato wart has been reported in Asia, Africa,
Europe, North America, South America and
New Zealand.
In New Zealand potato wart is restricted to home
gardens in the Southland region.
Actions to minimise risks
Figures 1, 2 & 3 courtesy of Hans Stachewicz, Institut für
Pflanzenschutz in Ackerbau und Grünland
© State of New South Wales through the Department of Trade
and Investment, Regional Infrastructure and Services (NSW
Trade & Investment) 2012. You may copy, distribute and
otherwise freely deal with this publication for any purpose,
provided that you attribute the Department of Trade and
Investment, Regional Infrastructure and Services as the owner.
ISSN 1832-6668
Disclaimer: The information contained in this publication is
based on knowledge and understanding at the time of writing
(June 2012). However, because of advances in knowledge,
users are reminded of the need to ensure that information upon
which they rely is up to date and to check currency of the
information with the appropriate officer of the Department of
Primary Industries or the user’s independent adviser.
Put in place sound crop hygiene including:
Published by the Department of Primary Industries, a part of the
Department of Trade and Investment, Regional Infrastructure
and Services.
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PUB12/70
sourcing seed potatoes of high health status
from reliable suppliers
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