G'day Ruth, the trouble with poisoning it is that it's going to be unsightly for a long time. I'd think the best bet is to get a young lad in to clean it up, but if you think that's going to be too expensive you'll have to find the main stem or stems where it comes out the ground, cut away the outside bark wrap an old piece of towel or other absorbent cloth around it and soak it with a strong solution of Roundup or similar poison. he blokes down at the hardware will tell you the best valur chemical for the job, but that's the best way of applying it.

If the weather is warm put some glad wrap over the cloth to keep it from drying out to quickly.