Native to North America, South America, and the West Indies, prickly pear (Opuntia species) is a highly invasive cactus plant. They compete with native vegetation and can form dense impenetrable thickets in pasture, offering refuge for pests such as foxes and rabbits and provide habitat for fruit fly.  

Murraylands and Riverland Landscape Board Senior District Officer Jodie Woof said people might not know that prickly pear produces fleshy fruit, which is a host for fruit fly.

“Our team are working with landholders to tackle incursions of prickly pear in the Riverland using biological, mechanical and chemical control,” Ms Woof said.

“It is important to have the right species of the biological control cochineal scale insect for its correct host cactus.

“We have set up nursery sites around the Riverland to breed specific species of the biological control insect for their host plant.

This insect sucks the moisture from the cactus pads until they become dry and die-off.

Ms Woof said using the cochineal biological control can be a very successful method over time for controlling large and small prickly pear species.

Landholders can remove minor incursions of cactus manually, but larger dense infestations may require removal by machinery.

Ms Woof said when undertaking manual removal, take care with the spikes and detached pads or segments. These can quickly regrow to form new plants. The removed plant material requires disposal by deep burial.

Cactus species respond well to stem/pad injection, and foliar spraying can be used with an approved herbicide.

“Our District Officers can advise landholders on appropriate control methods to remove this pest plant and assist with the hire of stem injection kits or release of the biological cochineal control.

“If landholders have prickly pear on their property, we are encouraging them to go out and have a look as they are currently fruiting. It is these fruiting species that can host fruit fly.

“Removal of unwanted and unmanaged prickly pear fruit can reduce fruit fly breeding areas,” Ms Woof said.

In South Australia, all but one species of prickly pear are declared pests under the Landscape SA Act 2019. This means the plant cannot be imported or transported in South Australia. The plant and produce are prohibited from sale, and landholders are responsible for controlling the pest plant on their property.

For more information on controlling cactus, contact the Murraylands and Riverland Landscape Board Berri on phone: 8580 1800.

For fruit fly zones and information about the current fruit fly outbreak please refer to the PIRSA website www.fruitfly.sa.gov.au.

If you see any insects of concern, please contact PIRSA immediately on the Fruit Fly Hotline 1300 666 010 or the Riverland Fruit Fly Co-ordinator on mobile 0475 945 227.

This project is supported by the Murraylands and Riverland Landscape Board through funding from the landscape levies.