The apple and stonefruit group claims MPI's "flawed" order will cause projected losses of up to $500 million over 10 years and set sector innovation back by up to 15 years.
Spokesman Paul Paynter, chief executive of the Yummy Fruit Company, said the group was open to giving MPI the time extension sought, "but on the basis that they now properly engage with us in order to find a sensible way forward".
"MPI's request for an extension places a significant question mark over the urgency claimed by MPI in relation to its previous directive and indicates that the biosecurity risk here is actually negligible," he said.
"Individually and as a group, we've had to jump at the demands of MPI and meet unrealistic timeframes for containment of plant materials. This has put us under significant personal and financial stress. Yet MPI want us to give them the luxury of time to review the situation and work at their own pace."
Paynter said some trees have been destroyed and most were contained, netted and sprayed. Trees in storage needed to be planted urgently or they would die.
MPI's Thomson said the ministry remained concerned at the biosecurity risk associated with the plant material.
The High Court judgment enabled MPI to make a new decision on how to manage the risk associated with the plants, he said.
"The judge anticipated it may take some time to do this which is why interim orders were put in place and parties were given leave to apply for extensions to these orders."
Plants at the centre of the row are derived from plant material imported from the Clean Plant Center Northwest, a quarantine facility at Washington State University.
The dispute relates to auditing of the facility.
The orchardist-nursery group said the facility had been providing plant material to New Zealand since the 1980s and was the main source of plant material and plant varieties for the country's stonefruit orchards.
All apricot, peach, nectarine, plum and a good percentage of cherry material comes through the facility, the group said.
The MPI order was issued to 32 sector participants in Hawke's Bay, Waikato, Nelson and Central Otago.