The national body tasked with making sure agricultural chemicals are safe is being crushed under the weight of product assessments amid an exodus of highly qualified staff.

The Australian Pesticides and Veterinary Medicines Authority (APVMA) approved 83 per cent of product applications within legislated timeframes in the September quarter, but completed just 42 per cent within timeframe from January to March.

One in five regulatory scientists have now quit the APVMA, as the agency forges ahead with a forced move from Canberra to Deputy Prime Minister and Agriculture Minister Barnaby Joyce's electorate.

Croplife chief executive Matthew Cossey said the relocation was crippling the plant science industry, but farmers were the real victims.

"Farmers are missing out on a significant number of important agricultural products, putting them at a massive disadvantage to their international competitors," he said.

A cost-benefit analysis of the relocation found that a one-year delay in the approval of one agricultural chemical product could cost the broadacre cropping industry up to $193 million.

The animal medicines industry said the backlog was affecting access to products such as sheep dips and pain relief for cats and dogs.

Animal Medicines Australia chief executive Ben Stapley said the issue was what happened for new innovative products.

"Products that might be better for the environment, safer, more effective but also cheaper," he said.

Mr Joyce turned his pet project into an election campaign promise last year and the agency is now relocating to Armidale in the New England electorate.

A cost-benefit analysis released months after the announcement showed the move would cost taxpayers $25.6 million.

In its latest quarterly report, the APVMA said the performance slump was due to "increased focus on addressing overdue applications, particularly in the pesticides area".

It noted the trend "is likely to continue" as the agency tries to overcome a backlog of applications.

Farmers and the veterinary industry rely on the regulator to ensure chemicals are safe and effective for use.

The head of the agency has already quit, and industries fear more scientists will go because they are unwilling to move to Armidale.

Canberra model did not deliver, says spokesperson

But a spokesperson for Mr Joyce said the agency's performance had long been unsatisfactory.

He said the overall time it took for both products and permits to be approved this quarter was 62 per cent, which is almost identical to the same period last year.

"Both results are unacceptable, which is why the coalition is looking at a new model for the APVMA," he said.

"The Canberra model has never delivered on the expectations of industry. The performance of APVMA is an issue that this Government is now actively addressing.

"That is why we are not just relocating the agency, we will be reviewing of all the processes and policies that underpin the work of the agency."

The spokesperson said the APVMA's performance was a matter for the agency's chief executive, not the Government.

The outgoing boss leaves her post at the end of this month.

