The boss of the national pesticides authority has refused to tell a Senate inquiry whether she will move with her agency to Armidale when her position is relocated there.
When asked about her own plans at a hearing of the Senate inquiry into its forced move from Canberra, Australian Pesticides and Veterinary Medicines Authority chief executive Kareena Arthy declined on Tuesday to answer, saying the matter was "private".
Industries and former public servants warned it would take the APVMA years to recover from its forced move.
Agriculture leaders said a minimum five-year lag on approvals for new pesticides would likely follow the agency's relocation, while Ms Arthy confirmed it would not be able to meet timeframe standards.
She told the inquiry it would take three to five years after its move in 2019 to reach a full complement of 150 scientists, and that it was impossible to say how the transition would affect its ability to approve pesticides and veterinary medicines on time.
But Ms Arthy warned that reducing its backlog was "going to be a lot of work".
A surge in resignations ahead of its move has hit the agency, which is struggling to meet required deadlines for pesticides approvals.
Twenty regulatory scientists and an additional 28 staff members, with 204 years' service between them, left the agency between July and February.
Staff surveys in 2015 and 2016 showed less than 10 scientists would uproot from Canberra to Armidale.
"With the relocation we have had several of our experienced scientists leave and that happened far earlier than I expected. In some ways I was expecting that to happen next year," Ms Arthy said.
The agency was trying to rebuild faster now after the unexpected surge in resignations.
Former APVMA boss Joe Smith said the loss of staff would be devastating to the agency.
"I genuinely believe losing that percentage of your staff would take several years to recover from," he said.
"I've got no doubt they'll be able to hire staff and relocate some, but to get them to a point they're familiar with the legislation, they're experienced with the processes, would take several years."
National Farmers' Federation manager of rural affairs Mark Harvey-Sutton told the inquiry a five- to seven-year lag on accessing pesticides would follow the APVMA move to Armidale.
"A relocation has been flagged and is happening and what we have seen is as an impact of that transition, a decline again in approvals. I think that really is our fundamental concern," he said.
Chemistry Australia policy director Bernard Lee said delays in pesticide approvals lost companies their competitive advantage in entering the market early.
"No proper functioning organisation could lose 90 per cent of its expert staff and not have a serious impact on their ability to do their job," he said.
APVMA scientist and Community and Public Sector Union member Ron Marks, speaking for the union, said the decision to move was causing stress and distress for staff.
Employees believed the government had ignored their legitimate concerns and represented these negatively.
Two years of "corrosive uncertainty" before the decision to move and inability to meet required timeframes had hurt morale, he said.
The APVMA assessed only 50 per cent of new pesticides within required timeframes between October and December, down from 82 per cent the previous quarter.