Stricter controls need to be placed on the movement of plant material around sites in Northland and elsewhere around the country infected with the myrtle rust, a Green MP says.
Steffan Browning, the Greens' spokesman on agriculture and biosecurity, said time was running out but there was still a chance of eradicating the plant disease before it became established in New Zealand.
To do so, however, the Ministry for Primary Industries had to use all the powers at its disposal, including putting controls on plant movements in areas where the fungus had been found.
So far only the only controls were on sites where the fungus had been confirmed or at nurseries that had traded with other nurseries known to be contaminated.
People who lived near infected sites were, however, free to move plant material around. That was "completely inadequate", he said.
MPI's reluctance to stop plant movements in the wider area around myrtle rust finds could have "grave impacts" on the chances of successful eradication or containment, jeopardising native trees such as pohutukawa, manuka and rata, as well as the feijoa and honey industries.
Mr Browning did, however, applaud MPI's efforts to get word out to the public through social media, printed material and signs.
Questions that remained to be answered included how many of the finds were from human-transferred contaminated plant material, and how the rust first arrived.
"MPI appears to have concluded that the initial incursion must be the result of a wind event with spores blown over from Australia and landing in hotspots in Aotearoa. While this may be the case, until this has been confirmed beyond any reasonable doubt, MPI must fight this battle to the greatest extent possible," he said.
Entire ecosystems could be affected because many birds, lizards and insects relied on trees such as pohutakawa, manuka, kanuka and ramarama.
As of May 26 the disease had been found at two sites in Kerikeri and one in Taheke, as well as 16 sites in Taranaki and one in the King Country.