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Potatoes Australia December 2016/January 2017
mechanisms of this suppression.
The hope is that one day we may
have biological control treatment
options for Powdery scab, or the
possibility of manipulating the
soil environment to optimise
disease suppression.
Department of Economic
Development, Jobs, Transport
and Resources, showed that
a soil from near Ballarat in
Victoria was able to suppress
Common scab and identified the
mechanism for suppression as
biological in nature. Dr Wiechel
and her team were then able to
show that through the use of pot
trials, the suppression was able
to be transferred to soils that
were susceptible.
Although we are a long
way off understanding the
precise mechanism that these
soil biological communities
appear to play in suppression,
there is some hope that new
management options may be
developed from this science.
The PPAA instigated and is
supporting a Hort Innovation-
funded project that aims to
explore known suppressive
Powdery scab soils and will
attempt to identify possible
disease despite the presence
of pathogen inoculum and
environmental conditions (cold
and wet) that are conducive
to the disease. Over 10 years,
research site pathogen levels
remained very low (with a range
of crop rotations including a
continuous potato crop).
Even when pot trials were
carried out using soil from the
various field plots that were
inoculated with Powdery scab
and planted with a susceptible
variety, little disease occurred
across all of the rotation
treatments. Plant & Food
Research scientists speculate
that soil biological communities,
combined with the soil type, may
offer the disease suppression.
Back home in Australia,
Dr Tonya Wiechel, working
with APRP at the Victorian
Australian potato processors
have identified Powdery scab
as having the biggest disease
impact on potato productivity.
Some producers in Tasmania
estimate that at least 10-20 per
cent of yield is lost to Powdery
scab root infection and that’s on
top of the volume of discarded
tubers affected by scab.
In 2013, the Australian Potato
Research Program (APRP)
estimated the cost of Powdery
scab to the processed potato
industry at AUD$13.4 million
per annum.
It was at a forum in New
Zealand that Simplot’s Frank
Mulcahy encountered work
led by Plant & Food Research
New Zealand’s Peter Wright
that showed evidence of what
appears to be a Powdery scab
suppressive soil.
These soils found in the
Pukekohe region of New
Zealand appear to suppress
WORK WITHIN THE AUSTRALIAN POTATO
RESEARCH PROGRAM SHOWED THAT
POWDERY SCAB WAS WIDESPREAD
IN PROCESSED POTATO GROWING AREAS
AND THAT ONCE SOIL WAS INFECTED,
THERE WERE FEW MANAGEMENT OPTIONS
AVAILABLE TO MITIGATE ITS IMPACT. IN
THIS COLUMN, THE POTATO PROCESSORS
ASSOCIATION OF AUSTRALIA (PPAA)
LOOKS AT POTENTIAL POWDERY SCAB
SUPPRESSIVE SOILS.
Gaining an insight
into Powdery scab
suppressive soils
For more information,
please contact Anne
Ramsay on 0400 368 448
or at
This communication
has been funded by
Horticulture Innovation
Australia Limited using the
National Potato Levy and
funds from the Australian
Government.
Project Number: PT15007
i
The PPAA held its Annual
General Meeting in early
October, where Peter
Hardman was re-elected as
Chair in his new capacity
as an independent having
retired from Simplot at the
beginning of August.
With a little more time on
his hands, we look forward
to Peter’s ongoing
leadership and advocacy
for the potato industry.
By the time you receive this edition of Potatoes Australia, you should be well into your
fungicide program, especially for Early blight (Target spot) and Late blight.
This is a friendly reminder that whatever chemical you are using, be it a protective or a
knockdown, adhere to the recommended intervals between applications. If the label says
7-10 days, don’t extend beyond the 10 days as you will have new vegetative growth on the
plants within your crop.
Also consider the amount of water you are applying. The more water used, the better
the coverage. Rates of 80 to 100 litres per hectare have proven to be less effective than
higher rates.
Keep your fungicide program up-to-date and talk with your agronomist or field officer for
more advice.
The other major task to consider at this time of the year is crop irrigation. Don’t let your crop
suffer with lack of water as it will cost you money at the end of the season.
AN UPDATE FROM THE PPAA CALENDAR REMINDER
Potato processing