Border district landholders say they fear they are fighting a losing battle against the invasive Harrisa Cactus despite some positive steps taken in control methods.
Landholders in the Goondiwindi region attended a field day on Thursday to find out the results of herbicide trials on the best control methods for Harrisia Cactus.
From March 2015 to December 2017, North West Local Land Servcies, in conjunction with North West Weeds and Waggamba Landcare, trialed 20 different herbicide options applied at various times of the year in an effort to determine the best course of action in containing Harrisia Cactus.
NSW Local Land Services senior projects officer Keith Walker said they had taken the learnings from the trials out into the paddocks so landholders could apply that information to their own specific infestations.
“Harrisia Cactus is a very formidable weed because with things like climate change coming on where our temperatures are going to be rising and the whole weather environment changing, it's going to be well adapted to changing weather systems,” he said.
“As a cactus it can put up with a lot of things.
“It'll have a long root that whilst you can spray the plant itself and kill of the fronds, you've really got to kill that too otherwise it's going to re-shoot.
“So it takes about three years to really get through a paddock and kill a plant.”
Based on findings from the trial, NSW Local Land services is recommending a slow-working herbicide that kills right through to the roots.
While the trial findings will make it easier for landholders to decide which herbicide is most suited to their properties and the infestations they face, many feel that the lack of government funding makes it a waste of their time.
Richard Doyle, Malgarai, Boggabilla, said there needs to be a far more coordinated approach to the control of Harrissia than what is currently in place.
“It’s having the resources we need to get on top of it,” he said.
“Council, Local Land Services and us landholders don’t have the budget to control it.
“It’s just getting away from us.”
Mr Walker said a far more targeted approach was necessary if there was going to be any hope of containing and controlling the pest.
“It would be good to have a bilateral agreement between Queensland and New South Wales to control Harrisia Cactus across the river,” he said.
The rise of Harrisa
Harrisia Cactus (Harrisia martinii) was introduced to Australia as a garden plant in the 1890s. Before long it had escaped into the natural environment and was first recognised as a weed in 1935 at Collinsville QLD. By the 1950s, Goondiwindi was battling its own infestation of Harrisia which began east of Goondiwindi.
The mid 1970s saw the biological contro, the Mealy Bug, released into the area and forty years on, it has failed to become the silver bullet many had hoped for. The Mealy Bug does not handle the cold or dry times well and is limited in the distance it will travel between plants.
The core infestation has now spread from east of Goondiwindi to Moonie, North Star, Toobeah and Yelarbon. Harrisia cactus is primarily spread by seed, however its fleshy stem segments do readily take root when they come into contact with soil. The seeds are spread by birds and other animals that eat the fruit, for example foxes, emus, pigs, goannas and ants.
Harrisia Cactus forms impenetrable thickets; reducing stock carrying capacity, preventing the growth of native grass species, and causes serious injury to livestock, horses and native species including the koala.
