What was once planted as a garden ornament from South Africa has become one of southern Australia's most pressing agricultural threats — a reminder that beauty introduced without foresight can quietly unravel the systems that feed us. Gazanias, now declared weeds across five states, are spreading faster than regulation can respond, forcing farmers in South Australia to spend money and tear at their own soil just to keep their paddocks viable. Researchers, growers, and regulators are each moving at different speeds toward a solution, while the weed moves at its own pace, indifferent to all of t
Australian farmers battle invasive gazanias with deep ripping and sensor spraying
By the time regulators sign off, gazanias will have spread across the whole state
Mark
So gazanias are just a weed now, but they started as a garden plant. How does that happen?
Mimi
They were brought in from South Africa in the 1950s and 70s as ornamentals—people liked how they looked. But they escaped cultivation and started spreading, and now they're declared pests in five states.
Luke
Do we know how they escaped? Was it deliberate dumping, or just people planting them and they seeded out?
Mimi
The source doesn't say. It just notes that people still try to plant them in gardens despite the ban.
Mark
And the farmers are using deep ripping—literally tearing up the soil—because there's no herbicide registered for gazanias yet?
Mimi
Right. That's the frustrating part. They're using combinations of herbicides off-label, and the trials show promise, but official registrations could take another year or two.
Luke
How much is this costing farmers? The source says it's expensive but doesn't give numbers.
Mimi
It doesn't quantify the cost per farm or per hectare. We know the GRDC invested $700,000 in the research, but what individual farmers are spending is not detailed.
Mark
And the good rainfall that brought this season—that's what spread the gazanias?
Mimi
The moisture helped them spread, yes. More water means more growth and more seeds.
Luke
But is gazania spread actually accelerating, or is it just more visible because farmers are paying attention now?
Mimi
The source says it's spreading into native ecosystems and across states, but it doesn't give before-and-after numbers on the rate of spread.
Mark
What happens if the herbicide approvals really do take another two years?
Mimi
Kaesler's worry is that the weed will be everywhere by then, and control becomes impossible. That's his fear, anyway.
The Pulse
- A bumper rainfall season — long awaited after years of drought — has paradoxically accelerated the spread of gazanias, turning a moment of relief into one of compounding crisis for South Australian farmers.
- Some paddocks are already lost to cropping, their soil moisture stripped by gazania root systems so aggressive that cereal crops planted alongside them simply die.
- Farmers are improvising herbicide mixtures without any registered product approved specifically for gazanias, operating in a regulatory gap that researchers hope to close within one to two years.
- Deep ripping — the most effective control method available — is costly, physically punishing to the land, and raises its own environmental concerns around soil erosion, leaving growers caught between two kinds of damage.
- Veteran farmers warn that the herbicide approval process is moving too slowly, and that public disregard for sale bans on gazanias risks undoing whatever progress the trials achieve.
What was once planted as a garden ornament from South Africa has become one of southern Australia's most pressing agricultural threats — a reminder that beauty introduced without foresight can quietly unravel the systems that feed us. Gazanias, now declared weeds across five states, are spreading faster than regulation can respond, forcing farmers in South Australia to spend money and tear at their own soil just to keep their paddocks viable. Researchers, growers, and regulators are each moving at different speeds toward a solution, while the weed moves at its own pace, indifferent to all of them.
A season of good rain across South Australia arrived with an unwelcome companion. Gazanias — flowering plants introduced from South Africa as garden ornamentals in the 1950s and 1970s — have spread across five states and are now choking paddocks that farmers had hoped to plant into one of the best seasons in years. Declared pests in South Australia, Victoria, New South Wales, Tasmania, and Queensland, they are moving faster than expected and pushing into native ecosystems where they threaten species of real conservation value.
La Trobe University researchers have been running trials near Loxton in the Riverland and at Arno Bay on the Eyre Peninsula, backed by $700,000 in Grains Research and Development Corporation funding over three years. The most effective approach found so far pairs deep ripping — machinery that tears weeds out by the roots — with targeted herbicide spraying, sometimes guided by video-sensor technology. But there is no registered herbicide specifically approved for gazanias yet. Farmers are mixing their own combinations while researchers work toward minor use permits or full registrations, expected within a year or two. Deep ripping works, but it is expensive and hard on the soil, raising concerns about erosion that researchers say must be managed carefully.
For Loxton farmer Paul Rudiger, the weed has already made some paddocks unviable. The moisture gazanias pull from the soil kills whatever cereal he tries to plant beside them. The ripping is punishing and costly, but it is the only thing keeping his crops alive. A few properties over, Paul Kaesler — whose family has worked the same land for more than a century — shares the relief that trials are showing results, but not the patience. He believes the regulatory process for new herbicides is too slow, and that by the time approvals come through, the weed will have spread beyond anyone's ability to contain it. He also points to a quieter failure: South Australia has banned the sale and movement of gazanias, but people still want to plant them in their gardens. That small act of carelessness, repeated often enough, is how the problem grew this large to begin with.
A good rainfall season across South Australia has brought farmers something they did not want along with the moisture: gazanias, a flowering weed that has spread across five states and rendered some paddocks too choked to plant. The plant arrived in Australia in the 1950s and 1970s as an ornamental—a garden flower from South Africa—but it has become a declared pest in South Australia, Victoria, New South Wales, Tasmania, and Queensland, and it is moving faster than anyone expected.
La Trobe University researchers have spent the past few years running trials on farms in the Riverland near Loxton and on the Eyre Peninsula at Arno Bay, trying to understand how gazanias grow and how to kill them. The Grains Research and Development Corporation has committed $700,000 to a three-year project that began after earlier surveys showed just how far the weed had already traveled across southern Australia and into parts of Western Australia. The research has also revealed that gazanias are not just a crop problem—they are moving into native ecosystems where they threaten plant species that have real conservation value.
The most effective approach so far combines two methods: deep ripping, which uses machinery to tear into the soil and pull the weeds out by the roots, followed by herbicide spraying. Some farmers have begun using video-sensor technology to target their sprays more precisely. Dr. Bajwa, one of the researchers leading the trials, acknowledged that deep ripping carries real costs. It is hard on the land, expensive to do, and it raises concerns about soil erosion and other environmental damage. But he said that if farmers use it strategically and sparingly, it can work. The catch is that there is no registered herbicide product specifically approved for gazanias yet. Farmers are mixing their own combinations, improvising as they go. Bajwa said the team expects to see minor use permits or full registrations for new products within the next year or two.
For Paul Rudiger, a farmer at Loxton, gazanias have already taken pieces of his operation off the table. Some of his paddocks are no longer viable for cropping because the weeds' root systems pull so much moisture from the soil that any cereal he plants dies. The deep ripping is punishing—it costs money and it tears at the earth—but he said it is the only thing keeping the gazanias under control enough to let his crops survive. This is bitter timing. After years of drought, this season was supposed to be one of the best on record for South Australian farmers. Instead, many are spending money and labor fighting a weed that should never have spread this far.
Up the road, Paul Kaesler, whose family has farmed the same land for more than a century, is also using ripping and sprays. He is glad the trials are working, but he is worried. He thinks the approval process for new herbicides is moving too slowly. By the time regulators sign off on new products, he said, gazanias will have spread across the whole state and no one will be able to stop them. In the meantime, he said, the public needs to follow the rules. South Australia has banned the sale and movement of gazanias, but Kaesler still sees people wanting to plant them in their gardens. That carelessness, he implied, is how the problem got this bad in the first place.
Notable Quotes
The crop, the cereal we sow around them will actually die because with their root system they take all the moisture— Paul Rudiger, Loxton farmer
I think that needs to speed up in some way or another or else they will be across the whole state before everyone knows— Paul Kaesler, on herbicide approval timelines
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