Wow, what a thread. Some great and wonderful information and great comments. Roundup is a great herbicide. There is no doubt about that. It kills anything green that it comes into contact with. It can also cause devastation to surrounding "wanted" greens if there is winddrift. It can also kill stuff like raspberry canes if it comes into contact with the canes. With some crops, it does not have to come into contact with the green growing part, I know. I have seen this happen to a small part of my raspberry patch. When using Roundup, be really careful about winddrift.
Evidently, once Roundup hits the earth, it becomes inert. But overuse of it I don't doubt for a minute can build up residue in the soil (if it is overused).
Sometimes the choice must be made, weed kill to allow crops to grow, or not. The crops won't grow with weeds that have overtaken them. Herbicides are necessary, used judiciously, no choice sometimes.
The problem with the spraying of herbicides is if it comes into direct contact with the bees or other bugs, it must not be good. Have a wonderful, beautiful day. Cindi