Veteran investigative reporter Powledge has a likely subject--the middlemen who control the movement of food from farm to supermarket, and how they jack up prices--but he never finds a focus. Farm production, we are reminded, has become more geographically concentrated and more geared either to contracts with Packers or to ""status"" trademarks (""Idaho potato""); the introduction of supposedly new and different products calls for more and more technical manipulation; marketing the goods involves large expenditures of energy, technology, and psychological flimflam; Uncle Sam connives at the resulting consumer exploitation. Powledge, however, fails to develop these givens in any coherent way. He lavishly illustrates points that hardly need illustrating (e.g., food advertising is full of bogus claims) while with-holding detail on issues that cry out for elaboration (the kind of contracts farmers have with packers or distributors). Enlightening treatments of, say, supermarket margins of profit and distributor control over shelf displays alternate with useless rhetoric about the Reagan administration truckling to ""the cholesterol lobby."" Statistics and facts are imprecisely brandished--as in a claim that the government has spent $8 million trying to rename trash fish: the new names were only a cosmetic touch in a general effort to bring some underutilized marine resources to public attention. Powledge's suggestions for future action range from the sensible (sort out your priorities as a consumer, set up co-ops, investigate farmers' markets) to the ludicrous (move to the city and become an urban gardener). Here, too, the command of details is spotty. (E.g., the United Fresh Fruit and Vegetable Association's guide to seasonal supplies of produce, recommended as a tool for informed shoppers, is mostly geared to Sun Belt agribusiness schedules rather than local crops.) For a systematic, chapter-and-verse look at the realities of modern agribusiness, no match for Jim Hightower's Hard Tomatoes, Hard Times; on the consumer end, informed journalists are more to be trusted.