Willows Cactus and support for Harrisia Cactus have taken another step forward to being included on a nationally significant weed list. Nominations for both species have progressed to detailed assessment. This final step before the review and approval will determine those weeds that are recommended for national coordination. AgForce has played a key role in the nomination process.
The detailed assessment will take some time, but we are hopeful to have a decision by late 2025.
AgForce Senior Policy Officer Dr Annie Ruttledge says she is pleased to see the two nominations moving forward.
"We're pleased that these two invasive cacti species have got through to this stage, it's not the final stage but it shows that the nominations were high-quality as they needed to be convincing to people who personally may not have come across these species."
Harissia Cactus (Harissia martini, H. tortuosa, H. pomanensis) and Willows cactus (cereus uruguayanus) have been causing significant problems for farmers and landowners in Queensland, including serious injury to people and livestock. Infestations can render pastures unsuitable for livestock, leading to significant economic losses for farmers.
An introduced 'mealy bug' (Hypogeococcus festerianus) insect has become established in Queensland for the biocontrol of Harrissia cactus and has demonstrated to help the reduction of Willows cactus as well. Although the mealy bug has proven effective in reducing growth and seed production, it does not handle the harsh temperatures of Southern Queensland well, so this bug cannot eradicate the issue on its own.
Dr Annie Ruttledge says a coordinated national approach is the best way forward to control the spread of this invasive species.
"A coordinated national approach would have benefits including increased resources and expertise to enhance the coordination and effectiveness of control programs, fund research into effective control methods, and run campaigns to raise awareness and encourage community involvement."
Weeds adversely affect our natural environment, agricultural productivity, cultural values, human health and community spaces, costing the Australian agricultural industry around $5 billion annually. A study has found that Harrissia cactus has been Queensland's most costly weed since 1960.
Springsure beef producer Trish Hawkins has been pivotal to the nomination process on behalf of members, she acknowledges that while the process has been lengthy, addressing the issue now, and on a national level, is crucial to preventing the further spread of these invasive cacti.
"Being proactive rather than reactive is essential. Neither of these cacti provide any environmental or economic benefits to anyone. If we tackle the problem before it gets out of hand, we'll save all stakeholders a significant amount of time and money."
Dr Ruttledge says the problems with Willows cactus are not well known, and the fact that Willows cactus continues to be sold as an ornamental plant shows that the information is not reaching plant enthusiasts, nurseries and plant distributors.
"Cacti might not seem like a problem in a pot in your garden, but if you dispose of it inappropriately, or if birds and other animals spread the seeds after eating the fruit, it can end up in all the wrong places. We know it can look pretty, but we can't control where it'll end up- and when it turns up in the wrong places the results are not pretty at all."
Image credit Queensland Government
