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)

Powdery Scab Management

As part of the Australian Potato Pest and Disease R&D Program, a guide on powdery scab management is attached. It is also available on the AUSVEG website

Professor Richard Falloon, Plant and Food Research NZ also recently completed a 3 year project investigating the properties of Spongospora suppressive soils in New Zealand. To find out more on the outcomes of this project please read his article here.

Additionally, the World Potato Congress held an excellent webinar on powdery scab in potatoes in March. This webinar, presented by Dr Leah Tsor, provides some useful guidance on how to reduce the risk of powdery scab through an integrated disease management approach. You can view the webinar here.

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 wildSolanaceoushosts.

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. South Australia is currently eradicating the viroid from one property.

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.
 

Transmission

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.

Control

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 ‘Block of 4’ approach to business continuity and interstate trade was first developed by Potatoes South Australia and AuSPICA in 2017.  With the support of the wider industry over several years, the concept to ensure business continuity was taken to the Plant Health Committee for consideration. 

The significant outcome is that:

The movement of fresh and processing potatoes tubers will occur across state borders in the event of an incursion of TPP (with or without CLso) in the Eastern states.

This provides a far greater level of assurance in the event of an incursion and stronger support for continued trade.  Risk assessments are being finalised in each state jurisdiction and the conditions will be developed and written into state legislation.

Seed potatoes are not mentioned in the communique, however, the Ausveg National TPP Coordinator , Alan Nankivell, will be facilitating workshops to find a way forward for the interstate movement of seed.

This process has demonstrated that the government is reliant on industry providing evidence-based information which can enable practical solutions to be made for industry benefit.   

It has been a long process but not without the necessary due diligence.

Click here to view PHC communique.

Sampling Protocol for CLso

Under a Hort Innovation funded project led by PIRSA-SARDI, a sampling protocol for CLso has been established. Potatoes South Australia assisted in its practical application on farm.

One of the outputs was a video demonstrating the protocol. You can view/download it here.

For more information, please contact Dr Danièle Giblot-Ducray at This email address is being protected from spambots. You need JavaScript enabled to view it.