A lantana-removal expert claims the spread of the poisonous weed is a "catastrophe" on a scale that has not been properly recognised or resourced.

Key points: Lantana has spread to an estimated 5 million hectares of coastal and hinterland areas of Queensland and New South Wales

Lantana has spread to an estimated 5 million hectares of coastal and hinterland areas of Queensland and New South Wales Stock that eat the weed are at risk of a painful death and rapid treatment is crucial

Stock that eat the weed are at risk of a painful death and rapid treatment is crucial Red-flowered lantana is considered the deadliest, and mature plants can produce up to 12,000 seeds every year

Introduced to Australia in 1841, the garden escapee is a restricted weed of national significance.

Creeping lantana is toxic to stock and forms dense, impenetrable thickets that smother native bushland and pasture, affecting more than 1,400 native species.

Biosecurity Queensland estimated lantana had infested 5 million hectares of coastal and hinterland areas of Queensland and New South Wales — an area just 1.8 million hectares shy of the whole landmass of Tasmania.

Young cattle introduced to a lantana-infested paddock are most at risk. ( Supplied: Lantana Removal Queensland )

Small infestations are already found in the Northern Territory, Western Australia and Victoria, with government mapping indicating it could also survive and thrive in coastal South Australia and north-east Tasmania.

Lantana poisoning results in severe sunburn and can be deadly to stock. ( Supplied: Qld Department of Agriculture )

Weed worry

Lantana Removal Queensland's Garry Herbert warned that landowners and all levels of government needed to do more to stop the spread of the weedy forms of the plant.

Stock that eat it risk a painful death and rapid treatment is crucial.

Poisoning symptoms included severe sunburn and liver damage with yellow discolouration (jaundice) of the whites of the eyes and gums, and skin of the nose and mouth.

Red-flowered lantana is considered the deadliest.

"There are only about two [lantana varieties] that are not toxic, the rest of them are toxic in varying levels," Mr Herbert said.

"Anywhere cattle have light-coloured skin, mainly their muzzles, the skin will fall off.

"Some of them have huge scars anywhere they are white, it just lifts the skin completely off the animal."

Birds eat lantana seeds, allowing the weed to spread. ( ABC Rural: Jennifer Nichols )

Most lantana poisoning occurred when stock unfamiliar with the plant were introduced to areas that were infested, overstocked or in drought.

There are two forms of lantana in Australia — the cultivated form is compact, non-thorny and produces few seeds.

But the weedy creeping form is a prolific seeder — mature plants can produce up to 12,000 seeds every year — with straggly, thorny stems.

Garry Herbert says lantana shouldn't be allowed to spread by roadsides. ( Supplied: Lantana Removal Queensland )

"They allow it to grow on the sides of roads, that gives it access to water all year round," Mr Herbert said.

"Every time the plant gets 25 millimetres of water it reseeds, it could seed six times a year — then that drops directly into the water course into the drainage ditches, straight into the creeks, straight into everybody's properties.

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"That's potentially 3,600 plants from one single plant.

"If you think of it to say, 'I've just killed 3,600 plants by taking one plant out', it helps people to understand how much power they have."

Birds and foxes eat and spread the seeds, which remain viable for several years.

Landowner Gary Hudson has spent more than $30,000 to have lantana removed. ( ABC Rural: Jennifer Nichols )

Prevention cheaper than cure

Gary Hudson spent more than $30,000 to have Mr Herbert mechanically remove lantana from his property on the steep slopes of Hunchy in the Sunshine Coast hinterland.

He was losing the battle against the unwanted invader.

"It was minimal when we first arrived, but the last 10 years it's become out of control," Mr Hudson said.

"It's really a problem that costs us and it costs all farmers up here and the community an awesome amount of money."

A Queensland Government flyer warned species affected by lantana poisoning included cattle, sheep, goats, guinea pigs and rabbits — but children could also be poisoned by eating the berries.

The National Heritage Trust noted that lantana "is also recognised as a serious threat to biodiversity in several World Heritage-listed areas including the Wet Tropics of northern Queensland, Fraser Island and the Greater Blue Mountains".

Gympie and District Landcare president Ernie Rider says lantana is a serious problem. ( ABC Rural: Jennifer Nichols )

Gympie and District Landcare breeds insects as biological controls against lantana, but the group's president Ernie Rider said results were patchy.

"Lantana is perhaps the major weed in Queensland overall," Mr Rider said.

"It loves the best agricultural soils, and the best grazing soils, it forms dense thickets and it's bad for the re-establishment of trees for environmental purposes.

"It has had about 40 or 50 biological control agents thrown at it … three or four of them [have been] quite effective, but the lantana species is a complex of varieties really.

"These new biological agents attack one of those strains and as soon as it's dying off, another strain just moves in and takes over so it's a really nutty problem."

Lantana quickly displaces plants, forming dense thickets. ( ABC Rural: Jennifer Nichols )

Biocontrol not enough

Other control techniques included fire, mechanical removal by dozing, slashing, cutting and aerial helicopter spraying.

A spokesperson for Biosecurity Queensland said the department worked collaboratively with other state government departments, councils and landowners to optimise the management of invasive plants and animals through the regular sharing of research and knowledge.

"Under the Biosecurity Act 2014, all lantana species are restricted invasive plants and must not be given away, sold, or released into the environment without a permit," the statement read.

"Everyone has a general biosecurity obligation to take all reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control."

Lantana is recognised as a weed of national significance. ( ABC Rural: Jennifer Nichols )

But Mr Herbert warned that leaving it up to local councils to enforce the biosecurity act on local landholders, had not succeeded in stopping the weed's spread.

"It's a catastrophe," he said.

"We have calls from people who are stuck because the property prices are half of what they would be if it wasn't infested, so those people have no out to get away from the material.

"If you fight a boundary war on your property, you're still better off. If your land's clean, you can still sell and leave.

"Within two years, there'll be no hiding from the photographic evidence and the fact that huge mistakes have been made and we're going to have to rectify them."