Many people may not be familiar with the harrisia cactus, but Ken Stower knows the pain its razor-sharp spines inflict all too well.
He was forced to euthanise his prized $20,000 bull after it stepped on the cactus and the thorns punctured its leg.
Ken Stower has been battling harrisia cactus on his property for years. (ABC Rural: Brandon Long)
“The spines are quite capable of going through a [four-wheel drive] tyre and if they can go through that they will quite easily go through an animal,” Mr Stower said.
“We had to euthanise him — it was difficult financially as well as mentally.”
Over the past decade he has watched the invasive weed spread across his 1,400-hectare property at Captains Mountain, 220 kilometres west of Brisbane.
“It’s gone from hundreds to thousands of plants everywhere,” Mr Stower said.
Ken Stower says having to euthanase one of his bulls due to injuries caused by the cactus was a mental and financial blow. (ABC Rural: Brandon Long)
A trip to hospital
Sally McKeering and her horses have been seriously injured by the plant.
“I’ve had a few really good horses that have been pretty much crippled from cactus getting in their coronet band just above their hoof,” she said.
While working on her cattle property near Alpha, more than 400km west of Rockhampton, Ms McKeering fell into a patch of harrisia.
Sally McKeering and one of her best stock horses were spiked by the cactus, causing pain and costing thousands in surgery and vet bills. (Supplied: Sally McKeering)
The spines pierced her glove and went into her wrist.
“Every time my hand or wrist would move, I could feel the thorns digging into me,” Ms McKeering said.
The doctors told her the thorns were so deeply embedded that she would need surgery to remove them.
Harrisia cactus has spread from North Queensland to southern NSW since the 1890s. (Supplied: QDPI/NSW DPI)
Costly species
The South American species was introduced to Queensland as a pot plant in the 1890s.
Birds and other animals have since spread it from Charters Towers in North Queensland to Marrar in southern New South Wales.
The numbers are difficult to pin down, but a 2021 study led by Flinders University Professor Corey Bradshaw found it was Queensland’s most costly weed since 1960.
In Queensland the management of invasive plants and animals is a responsibility shared by land managers, industry, the community and all levels of government under the Biosecurity Act 2014.
The Queensland Department of Primary Industries (QDPI) and its biosecurity arm often lead research in these areas and rely on funding from various sources, including the federal government.
It has acknowledged the cactus is not containable.
The fruit of harrisia cactus contains hundreds of seeds, which are spread by birds. (ABC Rural: Brandon Long)
“Harrisia’s eradication is not feasible due to its biology, resilience, and the extent to which it has spread,” a Biosecurity Queensland spokesperson said in a statement.
A QDPI paper last year highlighted the increasing density of harrisia in Queensland and NSW and at the 2024 Australasian Weeds Conference department scientists said alternative methods should be explored “before the situation deteriorates further”.
Landowners manage the weed with herbicides and biological control methods such as mealy bugs.
The mealy bug has proven effective in reducing growth and seed production in regions with compatible climates.
But Biosecurity Queensland said the bug struggled in areas with “extreme temperatures, such as southern Queensland and north-west NSW”.
A stem-feeding fly identified in Argentina is being tested as a potential new biocontrol agent and safety and efficiency tests are ongoing.
Mr Stower says applying liquid and pellets is a slow process. (ABC Rural: Brandon Long)
Calls for action
Mealy bugs have not been the solution Mr Stower hoped they would be.
He has had some success with herbicides, though he notes such treatments were time-consuming.
Ms McKeering, who farms organic beef, cannot use chemicals and must rely on mealy bugs to control the cactus on her central Queensland property.
They are working well, but they must be manually transported, which poses a logistical challenge.
This month she joined with other farmers, the lobby group AgForce and the NSW department of primary industries in nominating harrisia as a weed of national significance, which could attract more funding for control efforts.
Mr Stower agrees that greater funding and research is needed and is hoping for a solution as effective as the cactoblastis moth, which helped eradicate prickly pear.
“I hope that somewhere down the track, and pretty soon too, that we can find a cure for this cactus,” he said.
“It will be worse than the prickly pear if it’s not controlled, because you lose access to all of your country if this takes over.”
