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Potato mop-top virus

Potato mop-top virus

Potato mop-top virus (PMTV) is not known to be established in local ACT potato crops.

About the pest

Potato mop-top virus (PMTV) is a plant virus that affects potatoes. It is spread by a soil disease that causes powdery scab, a disease already present in Tasmania and mainland Australia.​

PMTV was first found in Tasmania in July 2025. Investigations showed it may have been there for a couple of years before it was detected.

In September 2025, it was decided that PMTV could not be eradicated, and the response shifted to long-term management. Biosecurity Tasmania is now working with potato industry groups to understand how to best manage PMTV and meet market access requirements.

Why they are a problem

PMTV can:

  • Affect the growth of potato plants
  • Reduce tuber quality
  • Lower crop yields.

Once it becomes established the virus can survive in the soil, even in the absence of a potato crop.

There are no food safety or human health risks. Potatoes with PMTV or powdery scab are safe to eat.

What to look for

Symptoms can appear on both the leaves and the potatoes themselves, depending on the variety and infection source. These may include:

  • Distorted or rough skin on the tubers
  • Deep cracking, or rust-coloured arcs, streaks or flecks inside the tuber
  • Yellowing leaves.

These symptoms only occur when infection is the result of infected seed potato, and even then, they are rare. The virus is not evenly distributed within the plant, which can lead to unequal symptom development within the plant and even between individual tubers.

PMTV can survive inside powdery scab spores in soil for 12 years or more.

3 images showing rust coloured arcs, cracking and streaks in the flesh of cut potatoes as described on this page.
PMTV symptoms in cut potatoes
Photo: Department of Natural Resources and Environment Tasmania

How it spreads

PMTV can move to new areas through:

  • Infected seed potatoes
  • Waste from infected potato crops
  • Soil stuck to machinery, tools, vehicles or boots.

Because the virus is carried by powdery scab spores, any movement of contaminated soil also spreads the risk.

More information visit Department of Natural resources and Environment Tasmania - Potato mop-top virus.

Report sightings

Report any suspected sightings to: