While other states have given up the fight against one of the world's most destructive horticultural pests, regaining fruit-fly freedom means survival for South Australian farmers such as Raj Ghuman.

South Australia is the only mainland state without an established fruit fly population, making it renowned for clean fruit and vegetables.

But the Riverland has battled 54 Queensland fruit-fly outbreaks since its first detection in December 2020.

The outbreaks are costing farmers millions of dollars to treat their fruit. 

Ms Ghuman, who owns Lowana Fruits, said the pest had threatened her family's livelihood in farming and the future of her stone fruit operation.

"It's costly, time-consuming, and a big mental stress," she said.

She said having to treat her fruit to sell to sensitive markets such as Adelaide had put enormous financial strain on their operation.

"We are hoping we can get out of the fruit-fly outbreaks … but, if not, maybe we have to stop the business," she said.

And it is not just growers throwing millions of dollars at it.

The South Australian government has spent $145.9 million on fruit fly eradication activities since 2020.

So, as the only pest-free area on mainland Australia, is it worth the cost of saving it?

Less chemicals to grow produce

Growing fruit in the Riverland has its advantages.

Produce from the internationally recognised pest-free area can be produced with fewer chemicals.

Farmers could fetch premium prices and gain access to more international markets before the pest-free status was temporary suspended due to the current outbreaks.

Since the outbreaks, farmers have had to follow treatment protocols to get their produce to certain markets.

Ms Ghuman was concerned about how treatment would affect the produce. 

"We need to spray every seven days and it's too much chemical on the fruit," she said.

Summerfruit SA executive officer Tim Grieger is among a cohort of farmers pushing to regain fruit-fly freedom.

Mr Greiger said the eradication efforts of the pest in South Australia were not just to the benefit of farmers, but also to consumers across Australia and the world.

He said growers would need to use more chemicals to combat the pest if fruit fly were to become endemic in the state.

"That's going against world trend and against what the consumer wants to see in terms of their produce," he said.

Depending on the type of produce farmers grow, different treatment methods apply.

Mr Grieger said fumigation was an option but it had detrimental effects on fruit quality and shelf life.

"If you can buy fruit from a fruit-fly-free area you know it hasn't been treated with a series of insecticides or fumigated," Mr Grieger said.

What's at stake?

About 95 per cent of South Australia's $1.3 billion horticulture industry is susceptible to fruit fly.

Primary Industries Minister Clare Scriven said the state government remained committed to an eradication strategy.

"We're doing everything that we can to make sure we can regain the pest-free status," Ms Scriven said.

Primary Industries and Regions SA fruit fly response general manager Con Poulos remained confident about eradicating the pest.

He said fruit fly numbers had been decreasing.

"We are not seeing a lot of activity in the 53 outbreak areas," he said.

He said eradicating the pest was also important for the way of life for backyard gardeners, the community, and consumers because people would not be able to grow fruit and vegetables in their backyards without fruit fly management controls.

"If fruit fly is unmanaged, it can have impacts on the productivity of the farmers, which would put up prices," Mr Poulos said.

"There's nothing worse than say if someone is selling fruit into a market that has larvae in it. That's a really terrible experience for consumers."

Cost and mental burden

Permanently treating produce to manage fruit fly is a reality South Australian farmers are fighting to avoid at all costs.

Citrus SA chair Mark Doecke said his industry alone footed an extra bill of $20 million per year for fruit cold treatment and transportation since the outbreaks.

"It's about $120 on every exported tonne," he said.

"There is extra cost sending our fruit to our own South Australian market, Western Australia, and Tasmania."

He said if fruit fly were to become endemic in South Australia, the cost for the state and farmers would be greater than the current eradication efforts.

Mr Grieger said the horrendous nature of the pest was poorly understood by people who had not lived with it.

"It's the world's worst, most destructive pest for fruit and fruiting vegetables," he said.

"That's all stone fruit, citrus, cherries, and many more."

He said he saw the impact on growers when he visited the Sunraysia region, where Queensland fruit fly had become endemic.

He said it required constant monitoring, baiting, and chemical use.

"The mental stress on farmers is huge," Mr Grieger said.

Protecting state's unique position

South Australia is home to about 4,000 horticulture businesses employing about 30,000 people.

National Fruit Fly Council manager Stuart Burgess said eradication was the key to farmers' survival in the industry.

"There is a heck of a lot at stake … people, jobs, the environment," he said.

Mr Burgess said multiple trade protocols would need to be renegotiated at extremely high costs if South Australia were to give up on fruit-fly eradication efforts.

He said the costs could push growers out of the industry.

The current fruit fly eradication response is the largest in the Riverland's history.

Mr Poulos, from PIRSA, said South Australia had a track record to eradicate every single fruit-fly outbreak over the past century.

"There is a commitment over decades to keep fruit fly out of the state," he said.

"We are determined to do it again."