Naturally-occurring biocontrol agents that have been the subject of more than 12 years of research are now being used in the field to help land managers control parkinsonia bushes.
Capsules containing endemic fungal cultures on millet seed and a semi-automated application gun, a process known as Di-Bak, have been developed by Bioherbicides Australia and were on show at Sam and Nicole Dart’s Keen-Gea property between Aramac and Torrens Creek recently, and on neighbouring Ulva and Tiree.
Desert Channels Queensland and Bioherbicides Australia gave the gathering of landholders and Lake Eyre Basin indigenous rangers hands-on experience in using the latest advance in the treatment of the Weed of National Significance.
It was part of a DCQ project to treat 5000 parkinsonia stems along six kilometres of Bullock and Wowra Creeks to help protect high value environmental areas such as the neighbouring Moorrinya National Park and Forest Den National Park further downstream.
According to project supervisor, Peter Spence, it was a practical tool that had come out of trials DCQ ran with The University of Queensland in 2010.
“It’s not the be all and end all, but it’s cheaper and easier than spraying, and clean to use,” he said. “It’s another really useful tool in the integrated weed control toolbox.”
Mr Spence said that while it was slow acting, the fungus was very efficient and safe, and had no effect on native plants.
“It can take a while, maybe six to 12 months, to start to kill, but it’s already spreading through the root system to kill other parkinsonia plants, including new seedlings,” he said.
“The best part is, with their applicator, even old blokes like me can probably treat 500 trees in a day because you’re not getting up and down all the time.”
With about a dozen people on site at any one time, and only two applicators and several hand drills, 5000 plants were treated in three days.
Once the capsule is inserted and sealed in with a plastic plug, plant sap dissolves the case and releases the pathogen to travel to the root system, from where it spreads through the soil to surrounding plants.
The new control method was sparked more than 12 years ago when a natural dieback episode was noticed in parkinsonia on Newcastle Waters Station in the Northern Territory, which resulted in the capsule of fungus that kills the trees from within.
To arrive at the final product, researchers identified around 200 endemic fungal cultures associated with natural dieback in parkinsonia, then tested them in field trials from Cunnamulla to the Gulf to arrive at the final three incorporated in the Di-Bak capsules.
The developers hedged their bets by including a fungus that thrives in hot, dry conditions with one that likes it hot and moist, and another that’s happiest when it’s cool and dry.
Mr Spence said both DCQ and Bioherbicides Australia would be monitoring the rate of dieback spread at the site and be looking to get additional landholders involved to expand the range of where dieback is established.
Landholders who have parkinsonia are encouraged to contact Peter Spence on 0428 580 629 or email@example.com.
The weed was introduced from Central America more than a century ago as an ornamental hedge and shade tree, and now covers some 800,000ha of Australian land.
It is a prolific seed producer and the pods are carried long distances by water. Once established, control is difficult and expensive.