A catastrophic new threat to Rocky's ecosystem
WITH BRIGHT yellow bulbs that mirror pom-poms and lush green fern-like leaves, the prickly acacia, under all of its external beauty has something to hide.
Under the appealing canopy of the seemingly innocent tree, the stems and branches exhibit needle-sharp thorns, which in the right density become an impenetrable trap for passing wild life, and suffocate surrounding flora.
Like many other Australian pests, the prickly acacia was introduced as fodder for cattle in drought stricken grazing land due to its resilience in drought conditions, but its very benefit has become its peril.
According to Councillor Neil Fisher, recent flood events have spread the prickly acacia around the floodplains of Rockhampton and now the invasive weed is becoming out of control requiring government intervention.
"The problem has become bigger than the council now, it would cost the entire annual budget to get on top of the weeds we know about in the area,” Cr Fisher said.
"The flower attracts small birds, which then attract large raptors (predator birds) which are dangerous to planes.”
Although the prickly acacia presents a new and unknown threat for Rockhampton, the weed has been causing devastation for years out west.
Leanne Kohler, CEO of Desert Channel, is a battle hardened veteran who has been leading the war on the weed for years, and knows just how formidable a foe the weed can be.
"At its worse, the bush can get so dense, it is impassible for even vehicles,” Ms Kohler said.
"A mature acacia tree reduces ground cover by 75-80 per cent, which means almost nothing can grow underneath it.
"Once mature (2-3 years from sprouting), the acacia will drop around 75,000 seeds per year and has a germination rate of around 85 percent.
"It's drought proof and when you basal bark (weed spray) it, it continues to seed, which then germinate so next year you're back in the same spot, doing it all again.”
Ms Kohler said water and cattle were the two key vessels responsible for spreading the weed.
Desert Channel has recently formulated a new plan to help the group get the upper-hand on the weed.
The plan involves sharing the workload with landholders by controlling weeds on their properties or reporting weeds in public areas to DC field workers.
Other methods include a new pallet-based herbicide called Tebuthiuron, which offers a scorched-earth approach but is the only herbicide able to eliminate the weed entirely.
"Seven grams under a plant will kill an acacia and anything in a 30metre radius, this means we are very selective and careful on how it it used,” Ms Kohler said.
"Land holders are also taught how to use the pellets responsibly.”
"Five years into the programs and we have less than one per cent collateral damage.”
"We have properties in the region which are acacia-free for the first time in generations.”
Land holders are compensated 50 per cent of the chemical's cost and the compliance rate is high, mainly due to peer pressure from neighbouring land holders who are pulling their weight.
Federal and State government funding for the Desert Channel's control program is set to run out by November 2018 (Federal) and early 2020 (State), and Ms Kohler is unsure whether the program will be re-funded.
Ms Kohler believed that recent flooding out west would see a catastrophic spread of the weed.
In Western Queensland, the acacia has the potential to de-value some property containing weed or cattle which has grazed on it, according to Elmes Rural in Longreach.