Forest and Bird admits eradication of myrtle rust was always going to be a challenge.
Two cases of the fungal disease have been discovered in the South Island's Tasman district for the first time, and the Ministry for Primary Industries (MPI) has given up trying to wipe it out.
But Forest and Bird conservation spokesman Kevin Hackwell says MPI could have done more.
"We have been really concerned that they have lifted their restrictions on movement, which we think is a real problem at this stage of the infestation."
MPI lifted a controlled area notice in Taranaki in February, saying it wasn't working.
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Mr Hackwell says we can all take vital steps to stop it spreading further.
"MPI could be saying look, at this stage we should be limiting the spread as much as possible. Yes it's going to eventually spread because its wind-borne, but we can slow it down."
MPI is looking now at a long-term management solution. Mr Hackwell says MPI needs an action plan, and fast.
"Right now, time is everything. We need to gain as much time as we can to be able to put in important conservation steps."
Myrtle rust was first discovered on the North Island mainland in May last year.