Australian workers will not be there to pick up the slack if the Federal Government's backpacker tax drives foreign workers away, South Australia's citrus industry says.

Key points: Australian workers 'moved away' from casual labour

Australian workers 'moved away' from casual labour Backpacker tax to come into effect July 1

Backpacker tax to come into effect July 1 Thousands of workers needed for a 'few months' annually

A new tax system for backpackers on working visas is due to come into effect from July 1 this year.

The changes will see working travellers taxed 32.5 cents from the first dollar they earn and a $18,200 tax-free threshold will be scrapped.

Citrus SA committee member and citrus grower Mark Doecke said Australia's horticultural industries relied heavily on seasonal labour.

He said the tax was sure to result in a sharp drop in the number of backpackers looking for work in the region.

"You need thousands of people for only a few months of the year and the locals just aren't there," Mr Doecke said.

"There's no Australian option to fill the gap that would be created by backpackers."

Australians 'don't like manual labour'

Mark Doecke said picking fruit was hard work, something many locals were not interested in or able to do.

"Australians have sort of moved away from the manual, casual side of labour into more degree-based, qualified employment," he said.

"They've just moved away from that style of work [and] they don't like manual labour much anymore.

"You can't have 1,000 Australians sitting around [in the regions] for eight months of the year and working for four months of the year. It doesn't suit people, which is fair enough."

Waikerie citrus grower David Arnold said the tax changes would put an unfair burden on growers and their workers.

"It's perishable crops [and there isn't] machinery, so it's all hand labour basically to get all of our crop off," he said.

"Thirty-two-and-a-half cents from the dollar is quite a bit of money out of their pay and they've still got to live here, pay for their accommodation and pay for their food."

After pressure from the fresh food and tourism industries, Federal Tourism Minister Senator Richard Colbeck is now conducting a cross-departmental review of the tax.

"We can only hope that they see some sort of fairness in it and look at a similar tax rate to Australians," Mr Doecke said.