Sixtus, who was one of five parties to seek a High Court judgment on MPI's original decision, said the United States-based Clean Plant Centre at the centre of MPI's decision, had stated it would not seek re-accreditation to New Zealand.
"That is a significant issue because that has been the main facility for the importation of new cultivars into New Zealand for probably 30 years.
"We can't just turn the tap on and off again as far as being able to do that."
The loss of the facility would have a long-term "devastating" impact for summer fruit.
"We could take 10 to 13 years to get back on track if Clean Plant Centre Northwest at Washington State University doesn't get accreditation.
"The whole diplomacy around this issue from MPI has been appalling."
MPI issued a contain and/or destroy order for tens of thousands of plants, after a routine audit in March found several critical non-compliances at the Clean Plant Centre Northwest. The MPI directive includes original plant materials imported between 2012 and 2017, and extends to budwood and propagated materials derived from the original plants.
Fruit companies Johnny Appleseed Holdings Limited - Yummy Fruit Company (Hastings), McGrath Nurseries Limited (Cambridge), New Zealand Fruit Tree Company Limited (Hastings), Pattullo's Nurseries Limited (Napier), and Zee Sweet Limited (Hastings) sought a judicial review of that directive.
The action was to protect New Zealand from potential biosecurity risk after an audit found significant failures at an overseas facility screening apple and stonefruit cuttings. MPI on its website said a routine audit in March found several critical non-compliances.
The order affected 32 orchardists, nurseries, importers and intellectual property companies in Hawke's Bay, Waikato, Nelson and Central Otago across a range of fruit-based industries including apples and nectarines in Hawke's Bay.
Following High Court action last week, MPI was directed to enter into dialogue with affected parties to find a solution. However, that judgment came too late to stop thousands of the imported plants being destroyed.
MPI's director of plant and pathways, Pete Thomson, said following MPI's audit, the US Department of Agriculture (USDA) conducted an investigation that confirmed findings of a "systemic breakdown in the facility's systems and adherence to MPI's requirements".
"The USDA advised their officials not to certify apple and stonefruit nursery stock from the facility for export to New Zealand until changes were made to MPI's and the USDA's satisfaction.
"We've been in contact with the facility and are waiting to hear back from them on the audit and steps they have taken so we can work towards re-accrediting them in the future. We also remain in contact with the USDA on this.
"There are three other offshore testing facilities accredited by MPI in Canada, France and Italy which provide a similar service for the horticulture industry, although some cuttings for pipfruit and stonefruit would only be obtainable through this facility."
MPI "remain concerned" at the biosecurity risk associated with the imported material.
"We can't be certain the plant material is free of pests and diseases of concern. Some of these pests and diseases can remain dormant for a number of years."
