Thanks EA - nice to see you here
Sorry I wasn't very clear about herbicide. Garlon is one of the herbicides that are particularly effective against blackberry, but in this state you need to have completed specialised herbicide handling training (ChemCert?), so often contractors are engaged when it's use is required.
On the other hand Glyphosate ('RoundUp' etc) can be used by any Jo Bloggs, but isn't necessarily the right thing to use for the more stubborn weeds... or you need to use a different technique when using it, to make it more effective. I'd be interested in success stories using that - maybe the 'Biactive' version (supposedly less toxic to aquatic creatures).
Blackberry is also one of those things that seem to be able to compete against any other plant, so 'competition' as a strategy probably isn't the way to go.
I'm interested in the 'burn' approach - maybe we could enlist the CFA as support if that's an effective option.
Is that one you've tried, EA?