THE MUSTER: ILLEGAL CACTI

The prickly issue of illegal cacti

Illegal sales of certain species of cactus are causing a prickly problem for farmers, people, pets, and native animals.

Words MICHAEL BURT

NSW Crime Stoppers, Local Land Services and the NSW Department of Primary Industries have joined forces to tackle the trade of illegal cactus species.

Cactus plants are popular potted and garden plants. They have an appealing aesthetic, are easy to grow, thrive on neglect and are a regular sale item at community markets.

However, some cactus plants – such as prickly pears – cause nightmares for farmers, and their sharp spines and barbed bristles can injure people as well impale, infect, blind and even kill native animals, pets, working dogs and livestock.

NSW Crime Stoppers, Local Land Services and the NSW Department of Primary Industries have joined forces to tackle the trade of illegal cactus species.

When invasive cacti get out into the environment, they can form impenetrable walls of vegetation that prevent animals from grazing and from accessing shade and water.

Farmers in North West NSW have experienced this first-hand in recent years, with outbreaks of Harrisia cactus and Hudson pear, both introduced to Australia as ornamental species.

There are more than 27 species of prickly pear cacti known to be in Australia. Eve’s needle, bunny ears, smooth tree pear and blind cactus are all illegal cacti species that are still being traded.

Cactus plants are popular potted and garden plants, but some species cause nightmares for farmers.

“Many people may not know the cacti they see for sale at their local market or online are illegal to sell or trade, so we have developed information to help people identify the types of cacti,” says NSW Crime Stoppers CEO Peter Price AM.

“If you have any of these plants, do not sell or swap them. These cactus infestations cost millions of dollars to control. Stopping the spread is the only way to minimise the devastating impact these plants can cause.

“We are appealing to the public to be on the lookout for the trade of these plants, particularly online.

“Community awareness and action will be crucial in preventing the prohibited selling or swapping of these plants. We are asking anyone who sees these plants being sold online to report it to NSW Crime Stoppers.”

On-the-spot fines of $1,000 and penalties of up to $220,000 can apply if someone is found to be selling or swapping certain types of cacti in NSW.

If you see illegal cacti being sold, report it to NSW Crime Stoppers by calling 1800 333 000, or online at nsw.crimestoppers.com.au. The website also has a fact sheet detailing a complete list of plants prohibited from sale or swap in NSW.

TINY INSECT EATS INTO HUDSON PEAR CACTUS

Farmers in North West NSW are winning the battle to control the spread of a prickly noxious weed thanks to a tiny insect.

With its Triffid-like prolific growth and barbed spikes that snare any creature unfortunate enough to walk into it, the Hudson pear cactus is like something out of a horror movie.

The tiny cochineal insect agent Dactylopius tomentosus attacking a Hudson pear.

But this has not scared off the cochineal insect agent Dactylopius tomentosus, which was first released for the biocontrol of Hudson pear in November 2017 in NSW and Queensland.

Four years on, the tiny bug is rivalling the success of Australia’s most famous example of biological control of weeds in Australia – the use of a cactus moth, Cactoblastis cactorum, to control prickly pear cactus.

This success story is led by Dr Andrew McConnachie, a research officer in the NSW Department of Primary Industries (DPI) Weed Research Unit, and around 50 landholders.

Andrew says the DPI has been mass-rearing the biocontrol agent in laboratories, with farmers providing Hudson pear samples in exchange for samples infested with cochineal to plant back in an impacted area and let the bugs do their work. “Now that the cochineal has dispersed so well through the landscape, farmers are battling to find any uninfected Hudson pear cladodes to collect,” he says.

Farmer Neil Warden undertaking one of his regular spraying missions to fight off the Hudson pear invading his Cumborah property.

Photo: Mardi Remond.

“However, biosecurity officers involved with the project are still rearing and releasing high numbers of the cochineal to help boost its impact on Hudson pear.”

“The cochineal biocontrol agent is established at all 44 field sites across Western NSW. Natural dispersal means it has also spread to an estimated 20 additional sites where it has not been released.”

Hudson pear was first detected in Australia in the Lightning Ridge area during the late 1960s. It is believed to have spread from a cactus nursery at Grawin and has since infested around 100,000 hectares of land in the North West.

According to mapping by NSW Local Land Services, the Hudson pear cactus has the potential to invade up to 112 million hectares of arid land across Australia.

Community members examining a Hudson pear killed by the cochineal Dactylopius tomentosus (lineage californica var. parkeri) at a release site in Grawin, NSW.

Photo: NSW DPI.

“The cochineal insect is proving to be specific to Hudson pear and is having a marked impact on its spread,” continues Andrew. “Biosecurity officers have also reported a significant decrease in the use of herbicides over the last couple of years, due to the impact that the biocontrol agent is having.

“NSW DPI has provided face-to-face training to over 50 landholders, and new participants are constantly getting involved. This has included how to safely collect Hudson pear cladodes, how to swap and transport the cochineal biocontrol agent, and how to release it. We are always on the lookout for more participants.”

The company InFarm has been contracted to develop an Artificial Intelligence (AI) approach for detecting Hudson pear from aerial imagery, which is being used to assess spread and the impact of the agent over large areas and across inaccessible terrain.

“Once this high-resolution imagery dataset is captured, it will be run through a supercomputer with a custom algorithm to determine exactly where Hudson pear is located in a 200,000-hectare area,” explains Andrew. “This data will feed into the Hudson pear management plan.”

The Hudson pear biocontrol project is funded through the Federal Government’s Department of Agriculture, Water and the Environment Rural Research and Development for Profit (Round 4) program, and is managed by AgriFutures Australia.

The not-so-nice Hudson pear

The Hudson pear is named after a resident of the Lightning Ridge area, Mr Hudson, who first brought the problem to the attention of the then Prickly Pear Destruction Commission.

Hudson pear has particularly vicious spines which are capable of penetrating footwear and even vehicle tyres.

The spines are encased in a detachable sheath, which can remain embedded in a wound even after the body of the spine is removed. The spines can cause serious injury to humans, livestock and working animals such as horses and dogs, and may present a severe impediment to mustering operations.

Hudson pear also poses a threat to native fauna and has been known to cause the death of native animals including koalas.

Infestations of Hudson pear cactus can also displace native flora and may have an impact on biodiversity.