Fleabane was a target for research, which is being led by CSIRO with significant and valuable co-investment from GRDC, because it is one of the most significant weeds in Australian cropping systems.
So we identified, and this is the aim of our project, to seek a biocontrol solution for helping to manage fleabane in an Australian cropping context to complement those other traditional ways of controlling fleabane.
It's the very first time a biocontrol agent has been developed and then being given release for fleabane in a crop setting in Australia.
And we know over the last few years that with herbicide resistance growing in fleabane populations and also increasing rates of spread across Australia, that it is time to have another tool within the toolbox.
So these long filamentous type structures here, that's what represents the fungus.
So there are several important stages with biocontrol research.
The first stage is to build international collaborations, and we work with people in the weeds native range, in this case Colombia, in South America, to help identify candidate biocontrol agents, in this case, a fungus.
So working with these international collaborators, the fungus was identified.
And then the next step is to bring the fungus into an Australian quarantine facility under high security, safely, to test the safety of the fungus on native Australian plants and also plants that are horticulturally and ornamentally important.
There were more than 50 non-target plant species and multiple replicates of those that were tested.
The assessments were undertaken over multiple years under those optimal conditions.
We found in not a single case that the fungus was able to reproduce over multiple generations on those plants, only on fleabane, its co-evolved plant.
Once we identified that the fungus was safe for release, an application for release was made to the federal government regulators, which was granted.
And we are now at the third stage of research, which is to release the fungus in collaboration with farmers into the Australian environment to help control fleabane.
So the fungus has a very simple lifecycle.
It has between one to two weeks it can begin infecting the plant.
It begins infecting through the release of a fungal spore.
Those fungal spores will land on a part of the leaf surface on the stem of the flowering stem of fleabane.
Then that spore will germinate.
And then the fungus that germinates will enter the leaf.
Once it's inside of the leaf, it will infiltrate the leaf surface and disrupt the ability of the plant to photosynthesise.
But once the fungus completes its lifecycle, it produces these black, brown, rusty speckles that we called lesions.
The leaf begins to yellow off, and it's those visible symptoms that indicates that the leaf has been infected.
So the outcome of that is reduced growth of that plant.
Now, in terms of the part of the plant lifecycle that's most susceptible, it's at the early stages of growth.
So the example that I have here are juvenile plants which are heavily infected with the fungus, what we term the rosette stage, and that will, through time over the next few months that the plant is developing, reduced the ability for the plant to grow.
What we're also seeing is if the plant is heavily infected, it leads to reduced reproductive output for fleabane as well.
I've been speaking with farmers now about the prospects of biocontrol for well over a year now.
There are two main questions that I get asked.
The first is about the safety of the fungus.
So it's very important for us to reaffirm to growers who are focused on caring for plants, caring for crops and getting good yield that this fungus is safe for release.
There's no prospect of non-target damage to crops or other plant species.
So re-affirming the safety is really important to me.
And the second is many farmers and this is, it's wonderful to have this interest, are hopeful that their fleabane populations will be completely wiped out by the fungus.
And so it's important for me to reaffirm the message that this is very much a slow and steady process.
Biological control is safe and it's sustainable, but it is not a silver bullet for completely removing a target weed from a landscape altogether.
What we would like to see is slow and steady reduction in the population size of fleabane, but most importantly, a reduction in the ability for fleabane to reproduce and set seed.
If we can crack that, that will be an excellent success for the program.