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of Bacterial wilt, it is
recommended to avoid growing
potato crops or other host crops
for a minimum of two to five
years in an infected paddock.
Crops such as peanut, tomato,
eggplant, capsicum, beans,
tobacco and even banana are
all hosts of the disease.
Growers are advised to control
self-sown potatoes and weed
hosts such as nightshade and
thorn-apple and avoid deep
ploughing infested paddocks
as the disease can survive
deep in soil. It is also
recommended to avoid
irrigation water flowing freely
over or below the soil surface.
Most importantly, it is
imperative that growers use
certified seed from reliable
sources and conduct regular
crop inspections for signs of
Bacterial wilt, and then destroy
any diseased plants.
To ease the threat of the
disease spreading, growers
should remain vigilant and
maintain good farm hygiene and
biosecurity practices by keeping
machinery clean and treating
infected land as a quarantine
zone to minimise the spread of
Bacterial wilt is one of the
most destructive diseases of
the potato, as it can cause total
crop loss and prevent the use
of land for potato production
for several years. It is a serious
problem in Australia, as well as
countries located in tropical and
sub-tropical regions.
A soil borne organism,
Bacterial wilt is caused by
the bacterium Ralstonia
solanacearum, which enters
the root system of the plant at
points of injury. It is divided into
three races based on the type of
host plant it attacks, and then
divided into four biovars based
on its biochemical properties.
The most widespread strain in
Australia that primarily attacks
potato crops is race 3/biovar
ll, which has been known to
occur in New South Wales and
Queensland. Two other strains,
which attack other host plants,
are confined to the Northern
Territory and Queensland.
The disease generally advances
in temperatures between
25-37 degrees Celsius, hence
why it flourishes in tropical
conditions and in a typical
Australian summer. In optimum
BACTERIAL WILT IS A MAJOR PROBLEM FOR POTATO GROWERS AND IT IS DIFFICULT
TO CONTROL AND ERADICATE DUE TO THE SOIL BORNE NATURE OF THE DISEASE.
POTATOES AUSTRALIA INVESTIGATES HOW GROWERS CAN IDENTIFY AND MANAGE
THE DISEASE TO PREVENT IT FROM SPREADING FURTHER.
Bacterial wilt under the microscope
temperature conditions, the
disease can spread by water
or contaminated/wet soil,
although it usually does not
cause problems when the mean
soil temperature is below 15
degrees Celsius.
In potatoes, Bacterial wilt
causes wilting, yellowing and
the in-rolling of leaves which
eventually die from the base
of the stem upwards. Wilting is
first seen as a drooping of the
tip of some of the lower leaves
of the plant, while stunting of
plants is also common.
Tuber symptoms include
brown-grey areas on the outside
and when cut, a white to brown
pus may appear and exude
from the eyes of the potato as
the disease advances.
The wilt bacterium can
survive for up to two to three
years in bare fallow soils, and
for longer periods in soils
cropped to non-Solanaceous
crops. The disease can also
be spread through infected
seed or a contaminated seed
cutter, as well as second-hand
bags or bins that have stored
infected potatoes.
To minimise the occurrence
the disease to clean areas.
Equipment should be left on
an infected paddock while it is
being worked and then washed
with a disinfectant solution in
a dedicated area after removal
from the paddock. Workers’
clothing and boots should also
be removed before leaving the
paddock and then washed in a
suitable disinfectant.
The content for this
article was sourced from
Agriculture Victoria. For
more information, please
visit
The topic for this article
was selected following
the results of PT13013
A review of knowledge
gaps and compilation of
R&D outputs from the
Australian Potato Research
Program.
This communication
has been funded by
Horticulture Innovation
Australia Limited using
the Fresh Potato Levy and
funds from the Australian
Government.
Project Number: PT15007
i
Bacterial wilt on a potato plant. Image
courtesy of Central Science Laboratory,
Harpenden, British Crown, .