The Labour Party says the Government should not be cutting jobs in biosecurity when New Zealand is at risk from imported diseases.
The kiwifruit vine disease PSA has been found at a Bay of Plenty orchard and could affect New Zealand's $1 billion kiwifruit trade.
The disease affects only kiwifruit vines and is spread by wind, bees and poor agricultural hygiene. Testing has begun to determine what strain has infected the plants.
Labour leader Phil Goff says the Government has been cutting corners in biosecurity, putting the country's $22 billion agricultural exports at risk.
"The Government's cut 54 positions, they've cut millions of dollars out of it - that is short-sighted, that is dangerous.
"We should be putting enough money into there, not cutting staff, not cutting millions of dollars out of the biosecurity budget."
But Prime Minister John Key rejected suggestions growers have been left vulnerable, saying a lot of resources have been put into MAF Biosecurity.
"The reality is, we don't know how the strain has got here, we don't know what strain it is. We just know it is part of the PSA virus. It could have been latent and there for a long period of time.
"I don't think we should jump to conclusions yet, but I'm confident biosecurity has the resources and is working well."
Biosecurity Minister David Carter says overseas importers have been alerted to the problem.