For longer than I care to remember, I've been getting drainage problems because of tree/plant roots growing into my drain pipes every few months or so. I have become well familiar with the issue. If the problem isn't too bad, I usually pour a few scoops of Root Rid (Copper Sulfate) crystals into the drain, last thing at night. If the root problem is more serious, I get a plumber to clear the drains with one of those roto tools. This clears out the roots thoroughly and the drains are cleared. I then keep up the Root Rid treatment for a few more weeks. The problem is the roots grow back later. I've been dealing with this problem for years and years, and I've had enough. I want to know if there is anything that is EXTREMELY toxic to tree/plant roots. I don't just want to use a chemical that will repel them from growing in the drains - no. Rather I want to use something that will kill the offending tree/plant, or poison it as thoroughly as possible. What is the equivalent of "cyanide" for a tree or plant that I can put into my drains last thing at night? The bottom line is I don't just want to repel the roots, I want to thoroughly poison the tree.