Harrisia cactus proves a prickly issue for NSW farmers 

Published: October 2019 I Edited by: Sandra Godwin

“Harrisia cactus needs to be controlled before the drought breaks,” says Boggabilla broadacre cropping farmer and North West Local Land Services board member Richard Clark.

Boggabilla broadacre cropping farmer, Richard Clark says that harrisia is going to become even more widespread following the break of the drought. Source: supplied. 
HARRISIA cactus was imported as an ornamental plant into Australia from South America in the late 1800s. Like so many of our most noxious weeds, no thought was given to controlling its spread. The current model is that the victim pays – the landholder, not the group that introduced the problem.

Like a lot of things, harrisia poked along at a very low infestation rate for 100 years. Then it reached a critical mass in Queensland, on the northern Darling Downs and the southern end of Central Queensland. A decade ago, it was a negligible problem in NSW, but it just seems to have exploded.

Matt and Lucy Godlee have spent more than $400,000 on herbicides to try to control harrisia on their property Urawilkie, near Goondiwindi. Last year Matt wrote an open letter to the then-federal Minister for Agriculture David Littleproud demanding he reinstate government funding for weed and pest control and research. 

Matt and Lucy Godlee, with their daughter Sarah, have spent $400,000 trying to control harrisia cactus on their property near Goondiwindi. Source: supplied. 

The Minister’s response said that controlling pests is a state government responsibility. I don’t agree. I think it’s a national issue. It needs a dedicated budget and a concerted effort from NSW and Queensland, potentially Western Australia and South Australia.
North West Local Land Services (LLS) has made harrisia control a high priority but does not have enough funds to come near to controlling the infestation or keep up with reinfestation coming over the border. We’ve spent our entire budget allocated to it every year to try and get it under control and it’s snowballing straight over the top of us.
Government neglects to control harrisia cactus

Harrisia produces a huge amount of seed in an attractive bright red bulb. The birds just love it, so under every roosting tree there’s a pile of harrisia and they fly south, west and east, and you get the same problem again. That’s how it’s spreading.

Also, cattle walk through it, the thorns hook into their skin and break pieces off which fall and grow roots. We’ve had an enormous plague of kangaroos in the last two years and they’re vulnerable, too. I’ve had to pull cactus out of the dog and the nose of a horse. Anybody who loves horses can tell when the horse’s got tears in its eyes. It’s horrible. It’s got a very nasty spike. It will overrun pasture and climb fences.

Harrisia is now reported in Northern Tablelands LLS, Central West LLS, and in Western LLS. It is advancing south through the state, but the only biocontrol is a mealy bug, which is not persisting south of Central Queensland. It could be that the bugs need wet summers, so they’re more suited to near the tropics. 

This is a biosecurity issue which, while not being ignored, is being neglected because the problem is so big no one land manager can be effective.
RELATED: Kicking up a stink: What’s bugging our biosecurity experts
It’s a difficult problem, complicated by the fact we might have an effective biocontrol down the track. That just gives the government an excuse to say: “Let’s wait for the biocontrol and do nothing”. In the meantime, it’s exploding and potentially mutating so that whatever biocontrol you’re working on won’t be effective when you release it.
The real issue is the lack of recognition of the problem and a lack of commitment to solving it. It’s got the potential to be the prickly pear of this century. 

That might sound melodramatic, but I’m sure there was a time when prickly pear was a minor problem in a small area and suddenly we had a disaster. By the 1920s more than 24 million hectares of farmland was affected. 

The Commonwealth Prickly Pear Board was created by the federal, NSW and Queensland governments and got on top of it with cactoblastis moth populations that expand as the prickly pear expands and contract as it contracts.

A thorny fight to stop the Hudson pear invasive species
Why are feral deer populations still protected?

Common pest prickly pear bearing fruit. Source: NSW Government, Department of Primary Industries/John Hosking. 

I think David Littleproud’s attitude underscores the difference in attitudes towards weeds and animal diseases. If it was foot-and-mouth, we’d have to de-stock a lot of country of cattle and sheep and the government would say it was a national issue. But because we’ve had to de-stock due to an incursive weed, it’s not a national issue. I don’t understand the logic. You either take it seriously or you don’t. The trouble is it’s not as dramatic as seeing trenches full of dead animals because of a disease. There’s plenty who’ve had to de-stock or reduce stock. 
At the moment that’s been disguised by the drought, but when drought breaks and harrisia takes off there’s going to be a whole lot of trouble. In all that time, we could have been doing something about it.  

What is harrisia cactus?
  • The cactus (Harrisia martinii, Harrisia tortuosa and Harrisia pomanensis) is a shade-tolerant perennial weed. Common names include moonlight cactus and moon cactus. Unchecked it will choke out pasture species.

  • Harrisia cactus flower. Source: Supplied. 

  • It is not one of the 47 weeds of national significance, nor is it on the national environmental alert list of 28 weeds that could become a significant threat to biodiversity if they are not managed. But it is on the NSW Department of Primary Industries list of 169 plants banned from sale throughout the state.

  • Harrisia cactus fruit. Source: Supplied. 

  • The flowers are large, pink and funnel-shaped with a tinge of white, and open at night. It produces a round red 4-5cm fruit which has scattered bumps, hairs and spines, year round. Up to 1,000 small black seeds are embedded in the white, juicy pulp of the fruit, which splits open when ripe.

  • Harrisia cactus seeds. Source: Supplied.

**These are the personal views of Richard Clark. If you would like to be ‘On my soapbox’ in a future issue of The Farmer, email: thefarmer@mediumrarecontent.com or write to: The Farmer, Suite 27/26-32 Pirrama Rd, Pyrmont, NSW 2009. If your topic is chosen, a journalist will be in touch.

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