A shortage of backpacker workers across three states is the worst ever seen by fruit growers and it is threatening the harvesting of crops.

The number of working holiday visas to Australia has dropped by 34,000 in two years, according to growers.

They say it is threatening harvesting because Australians do not want picking jobs.

Reasons for that include heat, according to the chairwoman of the growers' group Citrus Australia, Tania Chapman.

"The hard reality is locals don't want to go out there, they don't want to pick oranges," Ms Chapman said.

"They don't want to travel from within 10-15 minutes of their home. They think it's too hot out there, it's too hard a work, so we're heavily reliant on backpackers."



Ms Chapman said she has never known a shortage like this and some crops may go unharvested.

"It is hitting us badly right at this point in time," she said.

"Anybody who grows fresh produce of any sort knows that we only have a very short window of opportunity to get our produce off, to get it to market in optimum condition.

"The table grape season is about to hit on our doorstep so that flow-on will happen to them as well."

Citrus Australia said the areas affected include regions in South Australia, Victoria and New South Wales.

The industry body representing vegetable and potato growers, AUSVEG, warned that if the worker shortage was not addressed, there would be a greater reliance on imported produce.

"People tell us consistently they want to buy Australian produce, they don't want products from China," AUSVEG CEO Richard Mulcahy said.

Mr Mulcahy said paying people more to harvest produce would be "a seemingly obvious solution", but the reality was the industry was beholden to dominant supermarket chains.

"They drive prices down ... and they are just not going to accommodate significant increases in wholesale prices so that we can pay people who work for us more."