National Management Group (NMG) says decision reflects several difficulty detecting infected areas and the virus’s ability to persist undetected in soil
The potato mop-top virus (PMTV) National Management Group (NMG) has announced, with advice from the Consultative Committee on Emergency Plant Pests, that the virus is not technically feasible to eradicate from Australia.
The NMG said the decision reflects several challenges, including difficulty detecting all infected areas; the virus’s ability to persist undetected in soil; widespread presence of powdery scab (a known vector); and the risk of spread via seed, tubers, and soil movement.
In the coming weeks, the NMG will consider options under the Emergency Plant Pest Response Deed to support Tasmanian potato growers with financial losses and costs incurred.
PMTV was first detected in Tasmania on 15 July when an industry member submitted potatoes showing suspected viral symptoms to Biosecurity Tasmania. This was the first time PMTV has been identified in Australia.
A series of tests confirmed the presence of PMTV and Biosecurity Tasmania then established an Incident Management Team, which continues to carry out emergency response activities.
These include tracing the movement of risk items (such as potatoes, machinery/equipment, soil) associated with PMTV detections, and sampling and testing seed potatoes currently held in storage.
Response efforts have identified a total of nine sites of concern according to Biosecurity Tasmania.
“Seven grower sites from which harvested potatoes (currently in storage) have been tested and PMTV detected, and two other sites where PMTV has been detected in potatoes, including a small research site in the south and a storage site in the north,” Biosecurity Tasmania shared on its response page.
“PMTV has also been detected in samples from six single potatoes. One potato was found at a processing site, and five were bought as fresh produce from retail stores. The sources of these potatoes and links to any known infected sites are being investigated.
“Early traceback activities indicate that the virus may have been present in Tasmania for at least two years.”
As of 22 September, Biosecurity Tasmania said all generation 2-5 certified seed potato lines have now been tested for PMTV.
“PMTV was detected in only a small proportion of the significant volume of certified generation 2-5 seed that was tested,” it said.
“For the other lines tested, it is important to understand that a result of ‘not detected’ may mean either that virus is not present, or that it is present but below detectable levels with the sampling and diagnostic tools applied.
“Even so, the results provide information for the industry to act on for this planting season. There is sufficient seed for industry to plant only seed lines in which PMTV has not been detected.”
PMTV affects developing potato plants and is transmitted by a common soil-borne pathogen found in Tasmania and mainland Australia that causes powdery scab. The virus can reduce potato quality by causing skin distortions, cracking, and discolouration of the flesh, and may impact crop yields in some varieties.
There are no human health or food safety risks associated with PMTV or powdery scab. All potatoes remain safe to eat.
