Multicolour menace: these hardy daisies love Australian conditions – and are taking over roadsides

The Guardian

3 days ago

Scattered across Victoria's northwest Mallee region is a sea of yellow, orange and green. To the untrained eye, these plants could be mistaken for wildflowers. But ecologist Fiona Murdoch isn't fooled.
'My daughter is 19 now, but I remember dropping her at the kindergarten bus stop, and a little path of gazania was there, so I went to get rid of it,' she says. 'It spread all the way up the road and to her kinder, and I realised how invasive it was.'
Since then, Murdoch, who founded Mallee Conservation and is the secretary of stewardship organisation Land Covenanters Victoria, has made a point of controlling the spread of gazania near her property. 'It's been 15 years of constant vigilance,' she says.
Gazanias are brightly coloured daisies native to South Africa and have long been recognised as an environmental weed in Australia. But new research has found they are emerging as a highly invasive plant in grain production systems and grasslands, suffocating crops and costing farmers.
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Fast-growing, hardy and aggressive, Murdoch says the plants are similar to gorse and bridal veil creeper. She says they have 'enough resources to continue growing, flowering and to set seeds even if they have their roots in the air'.
'If you pull it out, it keeps going; it doesn't take up herbicide, so it's hard to kill by spraying, and it's allelopathic, so it stops other plants from germinating.'
Gazanias are listed as an environmental weed in Victoria, South Australia and Tasmania, and the sale of them is banned in SA. But the daisy can still be bought online in that state, and nurseries outside SA continue to stock the plant.
The Invasive Species Council is campaigning to have the plants removed from nursery shelves. But advocacy manager Imogen Ebsworth says it isn't just a 'rogue nursery problem'. It's a regulatory failure.
'The best solution is to follow South Australia's lead and ban the sale and trade of all gazanias,' Ebworth says.
According to the Invasive Species Council, about 75% of Australia's invasive weeds started as garden plants.
Ebsworth says until there were stronger national safeguards in place, the circulation of plants that were known weeds would continue.
'We are relying on everyday Australians to either have a botany degree or realise they need to research legally sold plants to find out if they are a weed,' she says 'That's a system designed to fail.
'That's why we need a national strategy – one that includes proper weed risk assessments and a clear, safe list of plants that shouldn't be on sale.'
Bunnings, Australia's largest hardware and garden centre chain, told Guardian Australia that it did not sell plants declared as weeds, but added that the list of invasive plants was different in each state and territory. It said it would continue to closely monitor lists for any regulatory changes and update its plant offerings accordingly.
Bunnings' director of merchandise, Cam Rist, says it sells a wide range of locally sourced plants across different stores and works hard to create an assortment that caters to customer preferences and demand.
'As always, we closely follow all relevant local biosecurity regulations and the advice of regulators about the plants we sell,' Rist says.
Murdoch says garden lovers could consider buying alternatives to gazanias, such as native daisies, which attract and support local wildlife.
She says the weed has now spread 'beyond the point of eradication', but that did not lessen the need to inform people about the risk of new plantings. 'It's about controlling high-priority areas,' Murdoch says.
'Adopt a bit of bush and say to yourself, no bit of gazania gets in here. You'll gain so many environmental credits.'