Trials to kill gazanias and help farmers reclaim paddocks - ABC News & Headlines – Australian Broadcasting Corporation

Gazanias may look pretty but they are an environmental pest that outcompetes crops and chokes out native vegetation.  (ABC Rural: Eliza Berlage)

The spread of gazanias from gardens is threatening valuable farming land and destroying native environments. 

Trials to control the invasive pest plant in South Australia, using sprays and cultivation, have demonstrated strong results.

Researchers are hopeful new chemical solutions to tackle gazanias can be registered for farmers to use in the next few years.

More rainfall across South Australia, yielding one of the best cropping seasons on record for farmers, has also helped to spread of one of their worst enemies: gazanias.

Introduced from South Africa in the 1950s and 1970s as an ornamental garden plant, gazanias are a declared weed in South Australia, Victoria, New South Wales, Tasmania and Queensland.

Researchers from La Trobe University have been conducting trials on farms in South Australia's Riverland at Loxton and on the Eyre Peninsula at Arno Bay to understand the pest plant's biology and how to control it.

La Trobe University scientists Ali Bajwa and Hoang TN Nguyen visited trial sites in Loxton to see the latest results. (ABC Rural: Eliza Berlage)

"[They] are also spreading into some desirable native ecosystems where we have some species that are high value from [a] conservation point of view."

The Grains Research and Development Corporation (GRDC) has invested $700,000 into the three-year project, with earlier work revealing the extensive spread of the weed across southern Australia and parts of Western Australia. 

Dr Bajwa said the best results in managing gazanias had been a combination of cultivation, which means using machinery to rip deeply into the soil to pull out the weeds, and then spraying herbicide mixtures, with some farmers using video-sensor technology.

"While cultivation is not desirable in these soil types and the sort of erosion risk or other environmental factors that can come with that, if we use it strategically once in a while that can potentially be a good option," he said.

Ali Bajwa says he is seeing up to 95 per cent of gazanias wiped out in paddocks using cultivation and sprays. (ABC Rural: Eliza Berlage)

Dr Bajwa said there was no registered product to control gazanias, with farmers using a mixture of herbicides to fight them.

"We're getting some very good results and hopefully within [the] next year or two we could be potentially seeing some minor use permits or potential registrations for this particular weed," he said.

Gazanias have rendered some of Loxton farmer Paul Rudiger's paddocks unviable for cropping, which is a blow amid a great season following years of drought.

Paul Rudiger is experiencing success with pea crops in some paddocks, while others are left bare due to gazanias. (ABC Rural: Eliza Berlage)

"The crop, the cereal we sow around them will actually die because with their [the gazanias'] root system they take all the moisture," he said.

While cultivation was intensive on the land and expensive to perform, Mr Rudiger said it was controlling the pest weeds enough to allow his crop to grow.

Paul Rudiger says he has been battling gazanias at his farm for the past few decades but the infestation is getting worse. (Supplied: Paul Rudiger)

Paul Rudiger says his machinery needed to go up to 250 millimetres down into the soil to rip out the extensive tap root system of gazanias. (Supplied: Paul Rudiger)

Up the road, Paul Kaesler is using cultivation and sprays to get rid of gazanias at the farm his family has worked for more than a century.

Paul Kaesler says gazanias have spread from nearby irrigation blocks along roadside verges to his paddocks. (ABC Rural: Eliza Berlage)

While Mr Kaesler is pleased the trials have yielded promising results, he is concerned that approvals for new herbicides are taking too long.

"I think that needs to speed up in some way or another or else they will be across the whole state before everyone knows," he said.

In the interim, he said it was important the public adhered to restrictions banning the sale and movement of gazanias in South Australia. 

Gazanias are sold as seeds and plants interstate but only sterile varieties are sold within South Australia. (Gavin McGrath)

"We still have people come through and go, 'Oh, I'm going to put them in my garden,'" Mr Kaesler said.