Last updated: 13 November 2025
What is potato mop-top virus (PMTV)?
PMTV is a plant virus (Pomovirus solani) that mainly affects potatoes.
Impacts on production may occur through yield losses or quality issues, however good management practices can significantly reduce this risk.
The virus is not a food safety issue, and potatoes exposed to the virus are safe to eat.
The virus can stunt plant growth by causing the sections of the stem between the leaves (internodes) to become shorter, giving the plant a ‘mop-top’, which is how it got its name.
Should the public be concerned about consuming infected potatoes?
No. There are no human health concerns associated with PMTV, and potatoes are safe to consume.
What variety of potatoes has potato mop-top virus (PMTV) been detected in?
PMTV has been detected in several varieties of potato grown in Tasmania.
At this stage there is no indication that the detection is associated with any single variety.
It is standard government policy to never identify information (such as varieties) that may identify individuals or businesses during any emergency response. This protects the health, safety and well-being of property owners and staff.
It also mitigates any reputational or financial damage that could occur in some circumstances.
Where were the detections made?
It is standard government policy to never identify the exact location of the properties linked to the PMTV detections. This is to protect the health, safety and well-being of property owners and operators.
The initial detection was made in the north-west region of Tasmania as a result of an industry member self-reporting symptoms of disease in potatoes.
We have not yet been able to confirm (and are unlikely to be able to confirm) when or how PMTV arrived in Tasmania
For more information on detections, please visit our current situation page.
How does PMTV spread?
The main ways that PMTV is spread is through planting infected seed potatoes and in soil containing spores of its vector, Spongospora subterranea, the soil-borne pathogen that causes powdery scab in potatoes.
Transmission by powdery scab is an important means of transmission for several reasons:
PMTV is not transmitted by aphids.
Direct transmission (plant to plant contact/foliar (leaf) contact) is possible; however, this is considered rare and is generally not effective.
Powdery scab can be spread through contaminated soil, farm equipment, seed potatoes, and water, potentially carrying PMTV with it.
Is the powdery scab vector present in Tasmania?
Yes. The pathogen that causes powdery scab is present in Tasmania.
Does PMTV affect other plants?
While PMTV can infect other plants in the Solonaceae and Chenopodiaceae families, the primary host is potatoes.
Biosecurity Tasmania is not currently testing other plants or plant parts, such as flower bulbs, or soil associated with flower bulb production.
Biosecurity Tasmania is conducting testing and tracing to examine all potential links with detections of PMTV. If potential links with other industries are found, these will be investigated in due course.
Is PMTV present in Australia?
PMTV is considered exotic to Australia.
The detection in Tasmania is the first report of PMTV in Australia.
This virus is found in most potato producing regions globally, including most recently in New Zealand where it is being effectively managed.
Is PMTV in Tasmania eradicable/has PMTV been eradicated from anywhere else in the world?
To the best of Biosecurity Tasmania’s knowledge, PMTV has not been eradicated from anywhere previously.
What are the potential impacts of PMTV?
PMTV causes tuber necrosis/’sparing’ (internal brown necrotic rings, arcs, and flecks within the tuber flesh) in sensitive potato cultivars (or varieties).
It could have an impact on processing potatoes due to a reduction in the quality of tuber flesh in infected stock.
PMTV may also result in yield losses, though there are variable reports of its impact in areas where it is present and managed overseas.
NZ, North America and Europe have been able to manage the disease effectively through good biosecurity hygiene practices, appropriate crop management (i.e. rotation) and good awareness across the industry of what to look out for.
What symptoms may be seen if a potato crop is infected?
The types of symptoms that may be seen in the field will depend on the potato variety and the environmental conditions that are conducive for disease expression.
It is important to understand that infected plants may not always show symptom.
Foliar (leaf) symptoms are not common and may be variable. Some varieties may show yellow blotches on leaves, whilst others show more ‘v’ shaped yellow patterns.
In potatoes infection may show up as rust brown discolouration within the tuber flesh in arcs/rings/flecks upon cutting. Sometimes these symptoms may be visible on the surface of the potato.
Symptom images are shown on our main PMTV page.
What can I do?
Implement and maintain good biosecurity practices on your property, including cleaning down machinery, equipment and boots before they come onto your property and prior to leaving.
Limit the movement of contractor vehicles within production areas and paddocks whenever possible.
Remain vigilant for any signs of disease in potato plants and potato stock.
Report anything unusual such as signs of disease or other pests to Biosecurity Tasmania at Biosecurity.Tasmania@nre.tas.gov.au immediately, or the Exotic Plant Pest Hotline at 1800 084 881.
Are there conditions for importation of Tasmanian potatoes into other states and territories?
Yes – you can find out more on our dedicated Exporting Potatoes to Other States and Territories page.
What management options should growers be aware of?
The easiest way for PMTV to move around is through soil contaminated with powdery scab. Ensuring all machinery that comes onto or leaves your property is free of soil or plant material is an effective way to reduce this risk.
When planting, use certified seed that has been tested and is free of the virus.
Where possible, avoid planting in powdery scab-affected paddocks and maintain long non-potato rotations.
Can growers do their own testing?
It’s important for all growers and industry participants to stay vigilant for signs of disease or other unusual signs of pests in potatoes and report them immediately to the Exotic Plant Pest Hotline on 1800 084 881.
Testing is available at Biosecurity Tasmania’s Plant Diagnostic Laboratories at New Town.
Unfortunately, there are no field kits for testing for PMTV available at this time.
Information for home/ community gardeners
Clean equipment before using it, after using it, especially if you plan on taking it to a different area or separate garden.
Clean down any shoes, before and after entering the garden. If possible, keep a pair of shoes dedicated to gardening activities.
Consider placing footbaths at entrances and exits in community gardens.
Only plant certified seed potatoes. Potatoes from the supermarket and roadside stalls should not be planted in your garden.
Ensure that visitors, staff and volunteers are aware of biosecurity requirements.
At home, potato skins and other potato waste can still go into green bins, home compost or general waste.
To maintain good garden hygiene, Biosecurity Tasmania recommends not using potato waste, or compost containing potato waste, on areas that will be used to plant potatoes in future.
Learn how to identify signs of PMTV and powdery scab.
If you would like to learn more about biosecurity for home and community gardens, visit AUSVEG's Community and home gardens: a guide to biosecurity.
For More Information
Potato Growers Biosecurity Manual (PDF 3Mb)
Biosecurity Checklist for Potatoes (PDF 247Kb)
www.farmbiosecurity.com.au
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