Dan Owens at Blog for Rural America has a discussion of the prohibition of planting fruits and vegetables on base acres. Marginal Revolution also has a post on the subject.
When I read the MR post I reacted--"this isn't right". Fortunately I did some checking before posting and found that the things I was challenging were indeed correct, or at least correct enough for purposes of discussing farm programs. (I don't think the bar's too high there.) I find I do that more these days; what knowledge I accumulated during my career is becoming obsolete.
I do remember when fruits and vegetables first came in, at least I think I do. It was the 1985 farm bill, which introduced the concept of "flex" acres, or 50/92--the idea that a farmer's payment acreage for a program crop could be planted to other than the program crop. We were working away on the implementation when the fruit and vegetable people started calling to ask what could be planted "other than the program crop"? We said, according to the way we read the law, anything. The next thing you knew there was a small little bill flying through Congress amending the 1985 act to exclude fruits and vegetables. From that little seed a mighty issue has grown.
Judging by the rhetoric around this issue, the only reason President George H.W. Bush didn't eat his broccoli is it was too high-priced--if we just had a few million more acres of carrots and broccoli prices would fall to the point that everyone would eat their 6 or 8 servings of fruits and vegetables a day. Pardon my skepticism, but while removing the prohibition might lower the price and expand the acreage a bit, I don't think it would mean a major change in the nation's diet.