How to kill Ivy now rooted in a stone wall so hard to reach

I have Ivy on a wall which is about 3m high and half concrete block and half stone with clay type material between the stones.
I can remove the Ivy from the concrete no problem and have cut through the base of the Ivy that spreads across both types of walls. Main trunk was about 6cm diameter, some has died but higher up the Ivy has re rooted into the soil so I would like to spray to remove it or it will pull soil from the wall.

I once asked for something to kill Ivy (here in France) and was given a small bottle of tree root killer to paint on. Never really kept at it.
I believe the old roundup (I still have some) will kill it but runs off the leaves so reduces it's effect. A neighbor killed some once when we were on holiday but waited till we left as he added a small amount of diesel to make it stick.
Anybody tried these or other solutions.

 

A sponge works better than a brush for me, seems to be less run off

 

Washing up liquid helps it stick to some extent or a drop of cooking oil but I think you might need a couple of applications.
I was under the impression that glyphosate was banned in France.
You could try one of those gas guns but you would need to keep at it for at least on season.

 

Thanks some good ideas, I have some roundup bought before the ban but that said farmers can still use it.
Washing up liquid and the bag / sponge idea sounds promising, less smelly than diesel. We have some of the ziploc freezer bags should work. So just pull back a piece to fit the bad and 'marinade' for a while.
I don't mind keeping at the problem, I usually just strim the lower stuff to shred it but the top is difficult.

 

Is SBK brushwood killer available to you? (Triclopyr)
I think (and its way back in the memory!) that aerial roots of ivy will not reproduce growth points once severed from the existing stem/budding points, but I will accept learned correction on this .
If its only 3m up, then it should be accessible to physically remove it.

 

I think if ivy is growing up a tree and using aerial roots as a climbing mechanism then, if cut it off from the ground it will die.
But if its aerial roots have access to soil and moisture it will continue to grow, it is just propagating itself.

 

I cut it low down but it has re-rooted in the stone part. I can get to it to cut some back but pulling the roots dislodges soil and the occasional stone so treating it is preferred.
I will give a try to cutting what I can and 'bag and spray' other parts, I will just repeat till it stops then I can keep it cut lower down to keep it in check.

 

Just like to add, the more foliage there is the better the uptake of glyphosate, so dont cut back anything you intend spraying.

 

I wonder if putting glyphosate in a plastic bag tied onto the bottom of the cut ivy might work? As the leaves transpire, they might suck the glyphosate up the stem.