I had some problems with these plants and cut them down. Now I have several healthy small ones instead of one very large one. I don't think you can kill these things. If you do, I will send you some small ones to replace them. (Not my favorite plant, but they fill a niche.)

We have a yucca colony that began as a single plant that became arborescent and eventually toppled over. It regrew in its original location from the root system, and the top of the fallen trunk started its own, new colony several feet away. There also are yuccas coming up along the trunk that's lying prostrate on the ground. Only the strong survive, and the yucca is definitely a survivor. Our yucca colony has been going through this process for more than fifty years and shows no sign of slowing down. One doesn't even have to dig a hole to plant a new yucca. Being careful not to impale yourself on the yucca's lethal spears, simply detach the green, growing end of the plant and place it wherever you want a new yucca; _et voila!_, you will soon have a fine, new yucca. Yuccas are an excellent alternative to burglar bars if your neighborhood is prone to burglaries. They also make a fine hedge to discourage visitation by uninvited guests--human or otherwise.