The CEO of a western Queensland group that’s battled Prickly Acacia infestations for over a decade says a single aerial photograph of their recent work has stirred considerable passion in her as efforts continue to eradicate the weed.
Leanne Kohler says one picture clearly illustrates what makes the Desert Channels Queensland program different, and why it has given hope to graziers that this insidious weed can be beaten.
“This single aerial photograph captures four key things that make our program so distinctive and successful,” Ms Kohler said.
She lists them off on her fingers like a successful stockbroker detailing her blue-chip stocks:
“You can clearly see the scale of what we are achieving - dead trees to the horizon; our claimed mortality rate of 99.96% is supported; all the native vegetation has been maintained; and the recovery of grass is obvious.”
What’s not obvious from the photograph are what Ms Kohler calls ‘the numerous critical elements’ making up a program that many doubted, but can no longer refute.
“We’ve had our doubters,” she said, “but they make you work harder, and when you crack the code and get the results no one else thought possible, the doubters spur you on even more.”
Longreach based Desert Channels Queensland (DCQ) started assisting landholders with Prickly Acacia control in 2004, but by early 2013 it was obvious that this strategy wasn’t working: the techniques available were not addressing the core seed-producing areas, and the 10/11 wet season had caused an explosion of germinations - DCQ mapping indicated infestations had tripled since 1996 and, that by 2030, 95% of the highly productive Mitchell Grass Downs would be affected.
On some properties, those wet season germinations destroyed 20 years of dedicated control work, with one couple admitting they were so devastated and despondent, they considered walking away.
“To hear that was gut wrenching,” Ms Kohler said.
“So we held a Prickly Acacia control field day in May 2013 to talk about new options and showcase the use of a helicopter UAV for applying chemical.
“But graziers told us that unless we could give them a cost-effective and efficient way of getting rid of the dense, high seed-producing infestations in watercourses and drainage lines, it was a lost war… they weren’t interested.
“It was a real wake-up call. We were already working on it, but this spurred the team on.”
These areas from which seed was continually spread by livestock to re-infest outside paddocks were already the focus of DCQ efforts, hence its partnership with PBE Services on the UAV technology.
But this ‘ultimatum’ from landholders made rapid resolution of the impediments to controlling these areas highly critical.
At the time, the only way for landholders to apply chemical near native vegetation and in watercourses was time-consuming and labour-intensive hand spraying, and for every tree they killed, a hundred came up the next year.
In comparison, the pelletised, residual chemical, tebuthiuron, at less than one-tenth of the treatment cost of spray chemical, stays in the soil for at least three years, killing current trees plus any germinations in that time. This is crucial given the half life of most seeds is 10 to 12 months.
“Working with our industry partner, PBE Services, we were able to do what no one else had, by getting all these different parts moving in the same direction at the same time,” Ms Kohler.
“While PBE and Yamaha Australia were perfecting the UAV, DCQ convinced the Queensland Government to issue a regulatory tool called an Area Management Plan that allows us to use tebuthiuron near native trees, as long as we don’t kill any mature ones.
“Then we got an AVPMA permit from the Australian Government to use tebuthiuron in ephemeral watercourses to control Prickly Acacia.
“Both of these tools are tightly regulated, must be overseen by us, and are tied to an approved DCQ 5 year weed plan for the area in question.”
At the same time, DCQ worked with the Department of Science, Information Technology and Innovation to identify the breakout infestations from satellite mapping so they could identify priority target areas.
This led to developing reciprocal obligations agreements with groups of landholders to work together with each other and DCQ to tackle the issue on a landscape scale.
“Finally, we started talking ‘eradication’ instead of ‘control’... it’s amazing the difference language makes to the mindset of those involved.”
The monitoring site results roll off Ms Kohler’s tongue.
“Ground cover up from 5% to 40%; grass species up from 2 to 6; grass biomass up from 100 kilograms per hectare to 1,500; costs down by more than 10 times; and 99.96% kill rate with the UAV.”
