4 days ago
Shoppers urged to change expectations as food disease found in Australia for first time
Consumers may need to change their expectations of how their food looks after an exotic disease that causes deformities in potatoes was found for the first time in Australia.
Potato mop-top virus has only been detected in farms in Tasmania, a state that produces more than 30 per cent of the nation's crop, but how far it has spread and when it first arrived in the country is still under investigation.
Luckily, infected potatoes are perfectly safe to eat, but unfortunately the disease causes ugly discolouration of their flesh and bumps on the skin, and it is incredibly difficult to get rid of.
Dr Nigel Crump, a potato pathologist with over 20 years' experience in the industry, explained the slime mould vector that transmits the virus can survive in the soil for up to 20 years. 'The good news is spongospora subterranea doesn't spread in the wind, but it lives in the soil and only really affects potatoes,' he told Yahoo News.
Crump doesn't expect most shoppers will encounter infected potatoes because supermarkets generally reject food with defects. 'Australia has a high preference for having perfect potatoes, but at the end of the day much of it is cut or peeled off. So we need to educate consumers,' he said.
As the director of peak body Potatoes Australia, he's mostly concerned that the virus could result in more food waste. 'That's going to be a real concern, because it could affect farmers' profits,' he said.
Potato mop-top virus can affect the leaves, shoots and tubers of potato plants, and studies in Scotland have shown that in a worst-case scenario, it can cause yield reductions of 67 per cent.
The virus is widespread around much of the world, and is established across the US, Canada, Europe, South America and parts of Asia. In New Zealand, it's been well managed since it was first detected in 2018.
Australia has been well prepared for its arrival here, and in 2022, the nation's seed certification inspectors were trained by a United States expert. The virus was first detected in July, but throughout the year, all exported potato seeds have been screened with PCR tests, similar to those used to detect Covid-19 to ensure they weren't infected.
Will the cost of potatoes increase?
Australian National University supply chain expert David Leaney explained that acting swiftly to contain the spread will be essential to containing its impact on Australian consumers. Because the wholesale and retail prices for potatoes could increase if the virus becomes widespread.
If that were to occur, processors would face increased costs in sourcing acceptable potatoes, and farmers in Tasmania could find their shipments subject to quarantine, stricter inspections, or even rejection.
Another cost farmers could face is the need to invest in enhanced biosecurity, seed certification, and soil management. He doesn't think shoppers would be looking at a large increase, but something closer to five or 10 per cent.
'It doesn't mean that only the price of Tasmanian potatoes is going to go up. Because of the state's significance to the Australian market, people buying potatoes in Sydney, could also see the price go up,' Leaney told Yahoo News.
Disease outbreaks have changed the way we farm
As Australia continues to embrace global trade, breaches of biosecurity are becoming a regular occurrence. Recent outbreaks include shot-hole borer in Perth that has resulted in the destruction of thousands of trees, fire ants which are spreading south from Queensland and threaten native species and agriculture, and varroa mite in NSW which attacks honey bees.
The nation is becoming more adept at responding to invasive diseases, and its experts are well aware of the harm outbreaks have caused in previous decades to food supply.
Leaney notes an outbreak in the 1950s of a strain of Panama disease, a soil-borne fungus that attacks the roots of banana plants, resulted in a global shift from Gros Michel bananas to Cavendish. And the citrus greening bacteria that causes bitter, misshapen fruit and irreversible orchard decline reduced orange production by up to 75 per cent between 2003 and 2023 in Florida, resulting in widespread job losses.
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The fungal disease wheat stem rust has reduced yields by 70 to 100 per cent in some parts of Africa. While over in Brazil, severe outbreaks of soya bean rust have led to losses of up to 80 per cent without fungicide treatment, creating volatility in global prices, because the nation is a major producer.
Leaney explained that history shows the best way to control vector-borne diseases is containment and resistance breeding, because they are too difficult to eradicate. But developing new varieties of plants can take years, meaning affected farmers may need to abandon infected fields in the meantime.
Reports of the disease can be made to Biosecurity Tasmania, or the Exotic Plant Pest Hotline at 1800 084 881. The public will be updated online at
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