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The tomato-potato psyllid, which vectors the bacterium that causes zebra chip disease in potatoes,
has been found in multiple locations in Perth and in the south west corner of Western Australia. Potatoes
Australia examines the impact the pest has had on the United States and New Zealand, where it has
been present for some time.
At the time of writing, tomato-potato psyllid (TPP) in Western Australia was being controlled under a
response plan that has not yet transitioned to management. In this article, Paul Horne and Jessica Page
from IPM Technologies, along with Anne Ramsay from the Potato Processors Association of Australia,
explain the benefits of using Integrated Pest Management when dealing with a TPP incursion.
THE ECONOMIC IMPACT OF TOMATO-POTATO
PSYLL ID OVERSEAS
USING AN INTEGRATED PEST MANAGEMENT STRATEGY
TO MANAGE PSYLL IDS
At the time of writing, the tomato-potato psyllid (TPP) has only
been identified in Western Australia, and measures have been put
in place to prevent its spread to the eastern states.
The pest attacks plants in the solanaceae family, including
tomatoes, potatoes, capsicum, chillies, eggplant and sweetpotato.
These crops were valued at over $120 million per annum in Western
Australia alone in 2014-15 and covered an area of approximately
2,000 hectares, with around 1,700 hectares of that devoted to
potato production at a value of around $46 million annually.
As the extent of the incursion is still unclear, it is too early to
make an accurate assessment of the economic impact of the
psyllid in Australia. The hope is that current control measures put
in place by authorities in Western Australia succeed in containing
the psyllid and preventing its spread to the eastern states.
At this time, the immediate economic costs will be borne
mostly by Western Australia. Beyond that, interstate trade in
affected vegetables and machinery will be disrupted.
LEARNING FROM THE PAST
Typically, the presence of TPP is associated with Candidatus
Liberibacter solanacearum, a bacterium that causes zebra chip
disease in potatoes. At the time of writing, the bacterium had not
been detected in Australia.
While the bacterium does not pose a risk to human health, it can
have a very real economic impact on the affected potato industry.
We can learn from the experience of New Zealand and the United
States, where growers have been dealing with the disease for some
time. In the United States, the disease was first reported in 2000
and quickly spread to include all the major potato growing regions.
Costs associated with control include a spraying schedule of up to
10 applications per season for potatoes.
The costs of ongoing chemical applications range from
around AU$1,700 per hectare in southern US states, to AU$4,000
per hectare in New Zealand. This includes the cost of chemicals
and labour, as well as machinery depreciation and maintenance.
Tomato-potato psyllid (TPP) vectors a serious disease of
potatoes that is caused by a bacterium, Candidatus Liberibacter
solanacearum (CLso). Significant losses (up to 50 per cent)
have been reported from potato crops in the United States and
up to 80 per cent in glasshouse tomatoes in New Zealand. In
processing potatoes, the bacterium causes zebra chip disease,
due to changes to the sugars stored in the tubers.
The good news is that the Australian potato industry recognised
the problem and the risk back in 2008 and commissioned a
project (PT09004), conducted by Australia’s IPM Technologies Pty
Ltd and Plant & Food Research New Zealand, to look for control
options within an Integrated Pest Management (IPM) strategy.
This was so the Australian potato industry could be prepared for
the very situation that we are now faced with.
A DESTRUCTIVE PEST
The arrival of TPP in New Zealand destroyed IPM in many crops
where minimal insecticide use had previously been practiced. This
included glasshouse crops where highly developed IPM strategies
had been implemented for many years. The initial approach to
dealing with this pest in New Zealand potato crops involved
regular (typically weekly) use of a range of insecticides, including
many broad-spectrum products.
When broad-spectrum insecticides are used against the psyllid,
it destroys the IPM control of other pests such as aphids, thrips
and potato moth, which can otherwise be successfully dealt
with using IPM strategies. Western flower thrips (Frankliniella
occidentalis), which vector tomato spotted-wilt virus, is resistant
to almost all insecticides available to potato growers, and so
poses a particular threat in this scenario.
TPP has natural enemies, such as lacewings and damsel
bugs overseas, but they are different species to those in Australia.
PT09004 aimed to confirm that the key beneficial species
necessary to prey on potato psyllid are already present in potato
crops in south-eastern Australia.
Farms also face the costs imposed by more rigorous on-farm
biosecurity measures in terms of the movement of labour and
machinery around the farm and ongoing pest monitoring. Farms
that exceed a pre-determined threshold of incursion may suffer
not only the loss of the whole crop, but also the additional costs
associated with the safe disposal of affected potatoes.
In the longer term, experience in New Zealand has shown that
yields can decline, not only from the presence of the disease but
also from soil compaction associated with additional machinery
movements over time. According to authorities in New Zealand,
yields have been falling for the past three to four years as a result.
The disease also had trade implications, with quarantines
imposed on US potato exports to the Republic of Korea. It also
raised concern among other countries about the safety and
quality of US potatoes.
FINAL WORD
As mentioned earlier, more work needs to be carried out by
various agriculture departments to assess the extent of the
incursion before the full economic impact of the TPP incursion in
Australia can be determined. There are too many moving parts to
predict what the ultimate outcome will be at this stage.
Suffice to say, the potato and wider vegetable industry is facing
a significant economic challenge in the coming months and
years. AUSVEG is working closely with authorities as they analyse
these issues and will keep growers informed whenever new
information becomes available.
PROJECT FINDINGS
The field work for PT09004 was funded by Australian growers
and processors of potatoes through the Australian Potato
Research Program. In that project it was confirmed that brown
lacewings, hoverflies, damsel bugs and a species of ladybirds
all accepted psyllids as prey, even in the presence of alternative
prey such as aphids. This means that the generalist predators that
are present in Australian potato crops are going to be extremely
important in controlling potato psyllid.
Field trials in Canterbury, New Zealand, confirmed that the draft
IPM strategy could be used to control all pests, including TPP. This
draft strategy involved the use of biological control agents, some
cultural methods and the use of selective insecticides.
IPM Technologies and collaborators showed that control of
TPP is possible without reliance on heavy use of insecticides. In
more good news, since this work was funded, newer selective
chemistries have been developed that are softer and with greater
efficacy, which means that managing the psyllid using IPM is an
effective and viable option for Australian potato growers.
IPM Technologies is currently funded by the potato and onion
industries to demonstrate the value of IPM through Horticulture
Innovation Australia-funded project MT16009 – An IPM Extension
Program for the Potato and Onion Industries. The project will
deliver workshops, training and one-on-one support, which is
timely given the current incursion of TPP and proven success of
managing the pest via IPM.
For more information, please contact AUSVEG at or
03 9882 0277.
This communication has been funded by Horticulture Innovation Australia
Limited using the research and development Fresh Potato Levy and funds
from the Australian Government.
Project Number: PT15007
For more information about the project, please contact Paul Horne and his team
on 0419 891 575 or email .
For more information about PPAA, please contact Anne Ramsay on 0400 368
448 or email .
Control of potato psyllid with an IPM strategy has been funded by Horticulture
Innovation Australia Limited using the research and development National Potato
Levy and funds from the Australian Government.
Project Number: PT09004
INFO
INFO
R&D | ECONOMIC UPDATE |
Paul Horne (right) discusses how to manage pests in potato
crops with grower Tony Cummaudo. Image courtesy of PPAA.
R&D | POTATO PROCESSING | TPP FEATURE TPP FEATURE