Flyboy,
I do fly ag, and it is as dangerous as you want to make it, like any other job. Spinning in while spraying? If one is sleeping, yes. Otherwise, that's a little like being afraid of exploding while sitting at a traffic light. I'm sure that somewhere it does happen...
You might want to read Part 137 which specifically exempts ag operators from most regulations, including specifically traffic patterns.
If you don't use your radio to spot traffic, but use your eyes instead, you'll be just fine. It is, after all SEE and avoid. Not hear, and avoid. There's a reason for that.
BD King, as for calling one's student "Dippy," it doesn't say good things about the instructor. If that's how you really feel about the student, it's just as well that you're not instructing full time any more. After all, the student pays your bills; the student is your employer. The student is the center of your reason for being...and if "Dippy" is the best token of respect you can muster for your client and employer, then it's time to find a job you can do, where you can be a benifit instead of a liability.