Potato Mop-Top Virus incursion
Potato Mop-Top Virus (PMTV) was found in New Zealand in September and Biosecurity New Zealand, part of the Ministry for Primary Industries (MPI), is working in partnership with Potatoes New Zealand to help manage the virus.
PMTV is a plant virus that largely affects potatoes and is a notifiable and unwanted organism in New Zealand under the Biosecurity Act.It is not a food safety issue and people can trust the potatoes they eat.
The virus is transmitted by the soilborne fungus which causes powdery scab (Spongospora subterranean), and can only survive long-term in the potato plant or in the fungus.
Once established in fields, the virus can survive in the fungus for up to 20 years in soil in the absence of a potato crop. The infection of the potato plant can be either directly from the infected mother tuber or through a current season transmission via a powdery scab infection of the roots. Transmission can occur via mechanical or soil transference so farm biosecurity is imperative at this time. Growers will be informed by MPI of management steps in regards to containment.
If established in NZ PMTV would be a manageable disease. It is established in North America and Europe where it is generally managed effectively without causing major production losses. However, where it is poorly managed it can create production problems for potato growers.
Affected potatoes can display both foliar and tuber symptoms of varying severity depending on the sensitivity of the variety and the source of infection, including;
• Distortions to the skin.
• Deep cracking, and rust-coloured arcs, streaks or flecks in the tuber flesh. • Yellow colouration on the foliar (mother tuber infections, as seen in photo one above).
While some varieties may show symptoms on the skin – PMTV may not be detected until the tuber is cut open. Some potatoes, while infected, may not show any symptoms at all, as in photo two above.
Growers have an important role to play in protecting their farms, their region and the potato industry from biosecurity threats.
If you suspect you have found PMTV on your property, contact the Biosecurity New Zealand Pests and Diseases hotline: 0800 80 99 66.
Help control the spread of PMTV by maintaining strict hygiene practices on your farms.