The Ministry for Primary Industries is closing down its biosecurity response for a potato virus, which has now been found to be widespread here.

The Potato Mop-Top Virus, or PM-TV, is not a food safety issue but it can cause defects in potatoes used to make chips.

It was first found in New Zealand last year, initially concentrated in grower paddocks in Canterbury.

The chief executive of Potatoes New Zealand, Chris Claridge, says early on in the biosecurity response it became clear that the disease would not be possible to eradicate, but it was thought it might be able to be contained on a regional basis.

But Chris says a national survey has since found the virus was present in many regions in both the North and South Island, indicating that it had been here for a long time.

"Given the lack of ability to contain it specifically to a region and eradicate, it was felt best to exit the biosecurity response and move to long-term management," Chris says.

Chris says PMTV was present in many countries and so far there had be little to no economic impacts for growers here that had PM-TV on their properties.

The Ministry for Primary Industries said in a statement it would continue to support the potato industry in helping them develop the long-term management plan, which would include non-regulatory controls and voluntary agreement.

"We've got a plan in development and that will incorporate research from world experts, in line with best practice. A positive outcome to date is that there have been no significant losses to growers attributed to the disease," it says.

-RNZ