Keep cutting it off Hank so it never gets the chance to photosynthesise. It may pop up further along in an attempt to keep going - pull the new shoots out if you can and weedkiller them if you can't. Eventually you will win so don't get disheartened.

Thanks S, i'll keep at it.

Use a weedkiller like SBK which is for shrubs and brush. Just make sure that you don't spray it on anything you want to keep.

Does SBK work on the soil or Bulba, ie will it also kill surrounding plants?

If you can't expose the woody root because its inaccessible, cut the bramble back, but leave an inch of stems - split them by cutting into them with something, so that they're splayed open a bit. Now apply the SBK Bulbaholic mentions, neat and not in a sprayer, but only enough to get on the cut areas, not on the surrounding ground. Now cover them with an upturned pot or something. If/when it regrows, it'll regrow through that pot and you'll be able to repeat this process quickly and easily.

This treatment is more effective if you can expose the woody, clumpy part of the root near the top of the soil, drill into it or cut it into it and apply the SBK to that.

Steragram - SBK poisons soil, and I never use it as a spray for that reason. I have successfully treated roots in the manner described in areas with dense planting, without any ill effects on the other plants. A couple of drops near the plant you're trying to kill on the soil won't be an issue, but more than that might be - I once knocked the bottle over and some spilled into the soil - the plant next to it didn't look well for a while, but it recovered.

Great stuff guys, will do as you say. Thanks.

Thank you Bamboo. We have used it on tree stumps but not anything else.

I wouldn't use SBK for reasons already give Use glyphosate as it is just as effective and doesn't poison the soil. Only it's a bit late in the year for that now.

Alternatively cut the bramble back so you can see where the main cane/s arise from the soil. Then dig around them until you expose the canes below their crowns. Sever the cane below that point with secateurs and the bramble should die.

Thanks B, but the root is 10 inches down between my immoveable fence and the side of my also immoveable raised bed and there's just 4 inches between them.
I guess I'll just have to use the SBK.

Sadly that only applies to young ones Bendipa - it just comes up further along its root if its well established.
Glyphosate doesn't claim to work on brambles - I wish it did.

OK Sue, as a last resort I'll just have to keep cutting them down. It'll keep me occupied.

Hmm, well Steragram's definitely right in that glyphosate doesn't kill brambles, but you might be interested to know that glyphosate binds to soil particles and has been known to be present up to 230 days later (though more usually about 56 days), and detected in root crops grown in glyphosate treated ground within that time period. On balance, I reckon a targeted shot of SBK directly onto cut wood and not anywhere else is less harmful.

Didn't realise that Bamboo - I thought that was just the trade name one (can't recall what its called)
Not something to use on the veg plot then.

Round up is the worst offender, you're right, Stera, but mostly because of other additives within the mix which make it more persistent. I think the figures I quoted (230 days) were actually for Round up, but it was the glyphosate itself which persisted. If you only use it on a couple of things and don't spray the whole plot with the stuff, I don't think its much of a risk - as always, these things are often about quantity (as in 21 pounds of chocolate eaten all at once will kill a human being, but half a pound won't!).

Lot of food for thought here. Thanks, I have what I need.