Landroverroy, did you ever get a weed wiper? I am after a largeish hand held one too to treat around the paddock edges, farmbuildings etc. I don't want to spray as we have water courses closeby but bushcutting/strimming just isn't effective enough especially this year - everything seems to be crossed with a trifid! Any feedback appreciated.
No I never actually got one.
However I can endorse what Robert says about using Roundup around water courses. We've used it on a large pond for eradicating reeds, having carefully researched it first, and it only affects plants.
I was looking for a tractor drawn weedwiper as we have several acres of bracken. In the end we chopped it and raked up and baled the bits, as bracken is poisonous to livestock, even when dried and dead.
Possibly in spring (if I'm feeling energetic
) I'll try some of your suggestions like thickened glyphosate applied with a glove/paintbrush/mop onto the new fronds and zap them before they take over again.
So watch this space for published results