Potato mop-top virus

Potato mop-top virus (PMTV) was detected in Canterbury in September 2018. Since then, we've confirmed the virus is present throughout New Zealand. The joint Biosecurity New Zealand and Potatoes New Zealand response to this disease has closed. From August 2019, the potato industry is leading the long-term management of PMTV.


Media release: Potato mop-top virus response closes out

Background on the virus and how it spreads

Potato mop-top virus (PMTV) is a plant virus that largely affects potatoes.

The virus is transmitted by the soil-borne fungus Spongospora subterranea that causes powdery scab, a common disease of potatoes.   

Once established in fields, the virus can survive in the resting spores of the fungus in soil for at least 18 years. Consequently, paddocks infected with powdery scab and PMTV will remain infectious for a long time. Eradication of PMTV in the presence of powdery scab is not possible.

The disease can be managed

While PMTV is confirmed present in New Zealand, it is a manageable disease. The disease is established in North America and Europe, where it is generally managed effectively without causing major production losses.

No food safety risk

There are no food safety risks from eating potatoes that have the PMTV virus. Potatoes remain safe to eat.

Help control the spread of the virus

You have an important role to play in protecting your farm, your region, and the potato industry from biosecurity threats.  

PMTV can be spread on seed tubers in soil associated with boots, in machinery, and in waste or by-products from potatoes. On-farm hygiene practices and developing a robust farm biosecurity plan are vital to try to minimise and help control the spread of potato mop-top virus.

Specific on-farm management measures include:

  • not growing potatoes in affected paddocks
  • cleaning and/or disinfecting equipment, machinery, and vehicles to avoid spreading soil between paddocks and properties
  • using signage to ensure workers and visitors are aware of biosecurity hygiene practices.

Find out more

The Potatoes New Zealand website has more information about good on-farm biosecurity practices and PMTV:

On the home front – protecting your assets

Potato mop-top virus

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