How to "kill" a tree root

Been asked by a friend on whats the best method. He`s got a smallish tree that has started to grow in between his/neighbours wall, he can`t get full access to the roots but there is about 2 foot of the trunk (about 4inch dia.) Only suggestion I could give him was to drill a 1inch hole and pop some round-up down it. Is this a good enough method or am I way off the beaten track.

Theres a product called "root out" (from horticultural suppliers ?) that will do the job far better.

Cheers very much for that

Old engine oil!!

A bloke in a nearby village drilled holes into a tree that was about 20 feet high and somehow poured in or injected paint stripper, It killed the tree in no time at all so i have been informed.

Might be worth a go, Its cheap enough.

I can tell you that Paint Stripper will definitely kill any plant life very quickly indeed. Essentially poisoning and burning the plant - destroying its ability to distribute and collect nutrients. There are any number of similarly poisonous and dangerous household and DIY products out there that are able to be poured onto plants to kill them if you want to risk it! Basically anything with a degree of longevity and highly acidic will do the trick. Paint Strippers a good one if you can keep the rain off it for a couple of weeks. I would drill as deep as you can into the tree near the stump on a downward angle, with the longest and widest drill bit you have got at least four or five times and then get a funnel and pour in the stripper. Then seal the holes with some waterproof tape, wrap the trunk in black binliners nailed into it and leave it for a few weeks. For a quicker result drill into any large visible roots of the tree as well and repeat the steps.

However, steer clear of actualy pouring it on the ground, It'll stay in the soil for ages! Also make sure no animals or people can get into direct physical contact with the treated parts of the tree.

It depends how big the tree is as to what options you have, as does the type of tree you have got.

I once tried this method with just Round Up on a young Sycamore tree. It worked for about a year but then the tree suckered up all over the place and I had to grind out the stump a section at a time in the end. If I'd known of the Paint Stripper solution then I would have used it.