High Priority Pests of the Potato Industry

The following pests are either exotic or currently confined to other parts of Australia, beyond South Australia.

Exotic pests:
  • Bacterial Wilt (Brown rot)
  • Tomato-Potato Psyllid
  • Zebra Chip
  • Potato Cyst Nematode (white or pale)
  • Potato Cyst Nematode (golden)
  • Late Blight
  • Potato Spindle Tuber Viroid (PSTVd)
  • Potato Virus Y (PVY) (exotic strains)
Regionalised pests
(not present in South Australia):
  • Potato Cyst Nematode (golden)
  • Bacterial Wilt (Brown rot)

Specific Information Weeds, Pests and Diseases (South Australia)

Branched Broomrape

It is anticipated that at the end of June 2013, the management of Branched Broomrape will be the responsibility of the farmer or property owner, in response to standards set by industry and requirements administered under the Natural Resources Management Act 2004. This is consistent with other agricultural weeds.

At the moment the weed is being managed by Biosecurity SA under the Plant Health Act 2009.  The Notice under this Act sets up a quarantine area and Code that affects all grain, horticultural crops, livestock, soil, farming and contractor’s ground engaging machinery and road making material.  Certification is required to move these items out of the quarantine area.  The Code is accepted by all States, except Queensland that applies its own additional regulations.

The Code and quarantine area will apply until lifted by the Minister for Agriculture, Food and Fisheries.  At this time the Natural Resources Management Act 2004 will apply as branched broomrape is a scheduled weed under this Act.  Management will devolve to Natural Resources, South Australian Murray Darling Basin, (the SA MDB NRM Board) who link into the Department of Environment Water and Natural Resources. As is the current arrangement, they will implement weeds policy developed at the State level by the Natural Resources Management unit of Biosecurity SA.

Potato Virus Y (PVY)

PVY is a serious disease of potatoes globally with crop losses of 80-90%.  Caused by an aggressively mutating virus, the disease of the Solanaceous group of plants (potatoes, tomatoes, tobacco and some weeds) is transmitted by many species of non-colonising aphids and by mechanical means. The virus that causes PVY of potatoes belongs to the Potyvirus genus. It can also cause decreased quality in the form of mis-shapen and cracked tubers, internal discoloration and mottling and chlorosis (yellowing) of foliage,  resulting in significant economic losses.

The disease has a significant impact on both seed and commercial production.

PVY management relies on prevention and disease minimisation strategies with the planting of certified seed being the first line of defence.

Potato Spindle Tuber Viroid (PSTVd)

Potato Spindle Tuber Viroid (PSTVd) is a quarantine pathogen of Australia and poses a serious threat to Australia’s potato and tomato crops.

A viroid is an infectious, circular, single stranded RNA molecule without a protein coat. It reproduces by taking over cell division and biochemistry in the host plant and so disrupts the host’s metabolism and manner of growth. The structure of the viroid makes it stable and allows survival in sap and leaf litter for possibly two years.

The primary natural hosts of PSTVd are potato (Solanum tuberosum) and tomato (Lycopersicon esculentum). All varieties appear susceptible with no natural resistance available in either host. Potato Spindle Tuber Viroid (PSTVd) causes a serious disease in tomato (Lycopersicon esculentum), potato (Solanum tuberosum) and eggplant (Solanum melongena). Natural infections have also been reported on pepino (Solanum muricatum), avocado (Persea americana) and sweet potato (Ipomoea batatas) and a wide range of wild Solanaceous hosts.

The viroid, which has evolved into numerous strains, is also present in Asia, Africa, North America, South America, Europe, and New Zealand. In Australia, New South Wales, the Australian Capital Territory, Victoria, Tasmania and the Northern Territory remain free of the pest. PSTVd is known not to occur in certified seed potatoes in Australia. There is a declaration of area freedom from PSTVd in South Australia. 

Due to the variability of PSTVd disease symptoms, mild infection can be confused with nutrient deficiency or toxicity, spray damage or insect damage. Aggressive infections result in reduced plant size, reduced yield, unusual tuber shape (infected potatoes often have a pointed appearance), reduced tuber size, thin stems and leaf distortion.

As a seed borne pathogen, this viroid has the potential to travel long distances in seed consignments. In potatoes, PSTVd can spread from one generation to the next via infected potato tubers. Once established, PSTVd infection is persistent and infected plants can become a permanent source of infection for neighbouring crops.
While the commercial host range is largely restricted to solanaceous species, such as potato, tomato and eggplant, a 2010 study conducted by researchers at the University of Western Australia found that non-solanaceous hosts can harbour PSTVd.


PSTVd is a highly contagious disease, transmitted between plants by touch.

The use of cutting or pruning tools, contaminated machinery or any form of physical contact between plants can result in disease transmission. PSTVd can also retain its infectious activity in seed for long periods.

In potatoes, PSTVd can also spread from one generation to the next through infected tubers.

Host Material

Potatoes for propagation/planting have been identified as the highest risk for spreading/transmitting PSTVd.


Keeping growing areas clear of weeds is important for reducing PSTVd infections. Overwintering of the viroid in weeds that have grown during a fallow period can prolong the infection period and put subsequent crops at risk.
Crop rotations involving non-PSTVd host species help eliminate infected plants. When cultivation of PSTVd host crops resume, extra monitoring for PSTVd symptoms and testing for the viroid is advisable.

Change of Country Status

The Consultative Committee on Emergency Plant Pests recently reached consensus that Western Australia and Queensland have cases of PSTVd that are not technically feasible to eradicate. This means that Australia can no longer declare ‘country freedom’ from PSTVd. In May 2015, the Australian Government Department of Agriculture notified the International Plant Protection Convention (IPPC), as is required when an exotic plant pest or disease cannot be eradicated from Australia.
Any unusual plant pest should be reported immediately to the relevant state/territory agriculture agency through the Exotic Plant Pest Hotline (1800 084 881). Early reporting increases the chance of cost-effective control and eradication.

Area Freedom Certificate

Plant Health Notice

Bacterial Wilt

Bacterial Wilt is caused by the soil-borne bacterium Pseudomonas solanacearum and is a serious disease for a wide range of plants.  In potatoes the disease is also known as brown rot, southern wilt, sore eye or jammy eye. It has caused losses to potato crops worldwide, and in tropical and sub-tropical zones almost total loss has occurred in severely infected crops.

Bacterial Wilt is a notifiable disease of potatoes in South Australia, and suspect diseased plants must be reported immediately to Biosecurity SA Plant Health.  The requirement for reporting is to comply with requirements for the sale of potatoes into Western Australia.  During past seasons, detections of Bacterial Wilt have been reported or detected in various potato crops located throughout South Australia.  With the assistance of the land owners these detections have been manage in accordance with agreed procedures to aid in the eradication of this disease from the growing sites.

Currently South Australia has no record of any detections of bacterial wilt.

Current Critical Exotic Disease Management

In the Australian Potato Industry there are two major biosecurity issues at present.  These are the management of Potato Cyst Nematode (PCN) and the prevention of the possible introduction of Zebra Chip disease complex.

Potato Cyst Nematode (PCN)

Globodera pallida (pale potato cyst nematode) and Globodera rostochiensis (golden potato cyst nematode) are recognised as harmful organisms for potato crops. They can cause significant yield reduction and economic loss to all supply chain partners in the Australian potato industry.

In 2005, the Australian industry, and both state and federal governments opted for a risk-based approach to potato cyst nematode (PCN) management and mitigation.  It was recognised that prevention and control were the only options for avoiding the economic impact that PCN would have on the Australian potato industry. The pathogen’s management and potential incursions of new and exotic pathotypes or strains needed to be under official control.

It is important for the future of the industry to maintain Australia’s status of being principally free of PCN, and provide certainty that the very limited areas where the pathogen Globodera rostochiensis only, is present, are subject to official control with the goal of possible eradication.

South Australia has no Globodera rostochiensis (golden potato cyst nematode)

Potato Cyst Nematode in Australia article - May 2009

Australian National PCN Management Plan

The Australian National PCN Management Plan has been in development for more than ten years. The Plan identifies the major risks for introducing PCN to un-infested land as being the movement of vectors (potatoes, nursery stock, root vegetables, soil, used machinery and equipment) from infested and linked land and the use of untested potato tubers as seed.

The Australian National PCN Management Plan June 2012 proposes continued government regulation of infested and inked lands, as well as the movement of PCN vectors off such land. It includes mandatory PCN soil testing for all potato seed sold for planting and industry adherence to a PCN Farm Hygiene Code of Practice.

The Australian National PCN Management Plan also proposes management of PCN on a property by property basis (depending on its PCN status) as opposed to the current model of controlling host movement from all potato properties within 20 km of a PCN infestation. Under this plan all land used for potato production is categorised as either:

  • PCN infested land
  • Linked land
  • Land used for potato seed production
  • De-linked land
  • Non-linked land of indeterminate status.

The plan was presented to the Plant Health Committee on 19 June 2013 by AUSVEG.  Updates on its progress will be provided.

Victorian Department of Primary Industry (DPI) Risk-Based Regulatory Reform Model (RBRRM)

Potato Cyst Nematode (PCN) is under official control nationally with all states and territories imposing restrictions on the entry of host material sourced from within 20km of a known detection or from the state of Victoria.

In November 2012, Victoria's Department of Primary Industries presented a reform model to the Plant Health Committee (PHC) recommending change to the management of PCN in terms of regulation. This included a focus of government intervention on controlling pathways identified as being a high risk for the entry and spread of PCN, whilst low risk pathways would remain the responsibility of industry. These pathways were identified in the draft Australian National PCN Management Plan now being finalised by AUSVEG. The reform model incorporates key risk elements and mitigation measures described in the Australian National PCN Management Plan.

The Risk Based Regulatory Reform Model focusses government controls on the management of:

  • Infested land;
  • Land classified under the national plan as being linked to infested land; and
  • Potatoes sold for planting.

Important principles underpinning national adoption of the RBRRM include;

  • Continued acceptance of current area freedom status of all states and territories irrespective of their previous testing history and linkages to PCN affected districts in Victoria.
  • Free movement of all host material from land not classified as infested or linked from Victoria to interstate markets – without the need for certification.

All states and territories have now endorsed the RBRRM (except for Western Australia) and have indicated legislative changes required to remove the “20 kilometres” rule will be undertaken once Victoria has implemented appropriate legislation controlling infested and linked land in the state.

The intent of this legislation is to:

  • Regulate the management of PCN infested and linked land in order to prevent the movement and spread of PCN to unaffected regions and states;
  • Orders and permits will require land owners to supply host material to approved markets only; and
  • Enable state jurisdictions with a current area freedom certificate to align importation Orders and take actions within their market if non-conforming produce is detected.

An industry circular from Biosecurity SA has now been released effective 1 November 2013.  It is available below.

Notice to producers processors and packers of Potato Cyst Nematode host produce

Model Legislation Summary Victoria

Out of Session Discussion Paper Risk Based Model PCN Management (3)

Potatoes South Australia Inc National PCN Management Statement - February 2013

Potatoes SA National PCN Management Q&A 4 -  February 2013

Zebra Chip Disease Complex

The Government of New Zealand’s Ministry for Primary Industries is seeking permission at an inter-governmental level for market access to Australia for fresh potatoes for processing, including French fry and potato chip production.

The Draft report for the review of import conditions for fresh potatoes for processing from New Zealand issued by the Australian Department of Agriculture, Fisheries and Forestry (DAFF) Biosecurity Australia on 3 July 2012 reassesses the risk management measures and import conditions currently recognised for an import pathway.

The Department of Agriculture, Fisheries and Forestry (DAFF) Biosecurity Australia proposes that the importation of fresh potatoes from New Zealand into Australia for processing be permitted subject to quarantine conditions. The import of potatoes for human consumption and for processing is currently prohibited entry to Australia from all countries. Cessation of trade with New Zealand occurred in 1988 when it was unable to meet the quarantine requirements for Potato Cyst Nematode (PCN). Australia is no longer PCN-free and New Zealand is currently requesting for trade to be resumed. However in 2008, the disease complex known as ‘Zebra Chip’ was reported in New Zealand. Australia does not have the disease.

Zebra Chip disease is caused by the bacterium, Candidatus Liberibacter solanacearum (Lso) and transmitted by the vector, the Tomato Potato Psyllid (TPP), (Bactericera cockerelli). TPP is a small flying insect pest which can also cause significant damage to most Solanaceous crops including tomato and capsicum, on its own. Together, TPP and Lso cause major yield loss with affected plants showing severe stunting, leaf chlorosis, scorching cupping and purpling, swollen nodes, and vascular tissue browning. Plants may also be killed outright.

Infected potato tubers display dark streaks, stripes, flecks or spots in their flesh when cooked, resulting in a downgrading of quality.

Lso and TPP was an accidental incursion to New Zealand in 2006, and by 2009 it had spread across the country.  Estimated loss due to Zebra Chip disease was $120m in 2011.  It has also caused major losses of hundreds of millions of dollars in the North American states of Washington State, Idaho and Oregon.  In 2012, there was a temporary ban on exports to South Korea, USA’s leading Asian market for fresh potatoes, due to the disease. It is estimated that the Australian industry could suffer yield losses of as much as 50% (equating to $1/4 billion) due to an incursion of Zebra Chip and other exotic diseases currently not in Australia should the Federal Government stall on banning the approval of market access.

The significance of the disease complex, the lack of basic knowledge on its epidemiology and the severity of its effects are reflected in the millions of dollars invested in research since its occurrence overseas.  In addition, Australia has a temperate climate which may prove to be ideal for the proliferation of the disease nationally. It is highly likely that the psyllid will enter Australia via easterly winds from New Zealand, or through transit on plant materials arriving from USA or New Zealand in any case, and the industry seeks to mitigate a possible earlier incursion by suspending market access.

In the meantime, there is significant on-going collaborative research by Australia (SARDI, University of Tasmania, Tasmanian Institute of Agriculture), New Zealand (Lincoln University's Future Farming Centre) and the United States of America concerning the disease complex and its management.

An Inquiry, concerning the biosecurity risks to the Australian potato industry of fresh potatoes imported from New Zealand for processing was held on 24 October 2012 in Canberra by the Senate Rural and Regional Affairs and Transport Committee. It was attended by representatives from South Australia, Tasmania and Victoria, together with representatives from AUSVEG and DAFF’s Biosecurity Australia.

Fourteen submissions from national stakeholders were received by DAFF and the Minister for Agriculture, Fisheries and Forestry, Senator the Hon Joseph Ludwig, including one from Potatoes South Australia Inc.

Following four delays, it is understood that the determination in this market access request is now scheduled to be released in early 2015. These delays have been largely due to investigation and analysis of the Risk Estimation Matrix (REM), a major tool employed by DAFF's Biosecurity Australia in assessing import risk.

From an industry perspective, it is considered that this is not about free trade or trade protection as Australia already receives processed products from New Zealand in the form of frozen French fry and crisp chips.  The industry is urging DAFF's Biosecurity Australia to continue this suspension of trade.  Despite the assuredness of quarantine rigor and DAFF’s commitment to maintaining Australia’s biosecurity, the industry continues to lobby the Australian Federal Government to reject this market access request.

At a State and National level, all primary production stakeholders seek to maintain our competitive advantage of growing (and value-adding to) premium food and wine from a clean, green environment.

In early February 2014, the Federal Department of Agriculture (DA) briefed the Senate Standing Committee on Rural and Regional Affairs and Transport on the Risk Estimation Matrix. On 28 February the Secretariat and Senators will present a Committee Report to the Senate.  Minister Joyce and the DA will then respond with a recommendation before mid-2014. Senator Sean Edwards will provide all relevant reports to Potatoes South Australia which will post them below.

Information Bulletin Zebra Chip Disease Complex Update - April 2015

Status of the Request by New Zealand to Export Fresh Potatoes for Processing Update - January 2015

Senate Inquiry Recommendations - NZ Imports - March 2014

Advice on the risk estimation matrix used by DAFF Biosecurity as part of the Import Rish Analysis process - January 2013

Proof Committee Hansard, Importation of potatoes from New Zealand - October 2012

Potatoes South Australia Submission to Senate Inquiry - October 2012

Select Committee on Sustainable Farming Practices -  September 2012

Biosecurity Australia - Draft Report Advice - July 2012

Draft report for the review of import conditions for fresh potatoes for processing from New Zealand July 2012

Zebra Chip Looking out for Psyllids - April 2012