my biggest bonsai mistake (so far)

I found this picture recently of one of my first ever bonsai trees. It was a pine that was grown from a small sapling handed out free during national tree week back in 1990. I grew it on and at some stage I decided to try to make it into a bonsai. I can't say it was particularly fantastic, but when this image was taken in about 2006 it had some potential. This was before I knew anything about wiring or styling. It survived a lot of neglect until one day, when it was very weedy I sprayed the base carefully with round-up. I wiped out all the weeds alright, but after about a month the tree began to turn yellow, followed by brown until the tree was completely dead. Maybe a few weeds are better than a dead tree....