The group had lodged a judicial review with the High Court at Wellington seeking to overturn the MPI decision, or at least extend the timeframes "in order for MPI to gather and consider all relevant facts", a joint statement said.
The statement said the MPI directive was "based on a paperwork issue", and there was no evidence of "an actual biosecurity risk".
No major pests or diseases had been found on affected apple plant material, but more testing was required for lower-risk apple pests and diseases, and for affected stonefruit material, an earlier MPI statement said.
No sign of disease in Central Otago has been announced.
An MPI statement last week said so far 24 owners had opted to destroy their plant material, and more than 200 plants had been destroyed nationally.
No breakdown on Central Otago growers was available "for privacy reasons", the statement said.
When asked about the judicial review, an MPI spokesman said: "We understand this is difficult for affected growers, nurseries and importers. MPI is confident with the decisions we have taken and our processes. We have carefully assessed all of the risks associated with this plant material. Our decisions are about protecting New Zealand and our wider horticultural industry from biosecurity risks. We can't comment further as the matter is before the courts."
pam.jones@odt.co.nz