Scott Morrison has warned fresh produce could be left to rot on wharves if Labor adopts a "militant" union proposal to reintroduce industry-wide bargaining.
The prime minister said the enterprise bargaining shift would plunge Australia back to the chaotic strikes and stoppages of the 1970s.
"I'm for a vision of Australia in the workplace which is bringing Australian employees and employers together," Mr Morrison told reporters while visiting a strawberry farm in southeast Queensland on Monday.
"Not following some militant union agenda which tries to drive people apart."
Mr Morrison praised small businesses across the country for defying the unions.
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"One of the reasons why small and family businesses are so successful is they just have no truck with any of that nonsense," he said.
Industry-wide bargaining will be up for debate at the ALP national conference next month.
Qantas boss Alan Joyce has expressed fears the industrial relations overhaul would cripple thousands of the airline's suppliers, cost jobs and threaten national prosperity.
Opposition assistant treasury spokesman Andrew Leigh declined to rule out the idea.
"We're open to changes that see a fairer industrial relations system," Dr Leigh told Sky News on Monday.
"We'll have those conversations with employers, unions, and other stakeholders."
