I am pretty certain crop insurance was around before the 80's. I just am not sure how much it was subsidized.  I don't think it was heavily used in the 70's and early 80's.

I am pretty certain that it was revamped in the 80's, maybe late 80's or early 90's.  I am pretty certain there was substantial disaster payments as a result of the drought of 1988, and that leads me to believe that crop insurance was revamped after that.