Since his graduation from Harvard University a quarter-century ago, Carl A. Pescosolido Jr. has worn more hats than a haberdasher's mannequin: English teacher, football coach, retail heating oil distributor in Massachusetts, citrus farmer in California's sun-swept San Joaquin Valley and, most recently, paperwork reduction zealot.

Pescosolido's paperwork fight began as a byproduct of his crusade against the Agriculture Department's 45-year-old system of marketing orders, which control the flow of produce to the market.

The marketing order system relies heavily on forms filled out by farmers when they pick, load and ship their crops. In 1981, Pescosolido, who had briefed himself on the requirements of the Paperwork Reduction Act, found the forms he was required to send to the Navel Orange Administrative Committee hadn't received a seal of approval from the Office of Management and Budget.

Aha! Without an OMB number, he knew the law said, the form was not legal and could be ignored. And as of Jan. 1, 1982, he stopped filling out the forms.

USDA Secretary John R. Block, who already had discovered the problem of the uncleared forms, got the OMB to approve the forms in late January on a temporary, emergency basis. The approval was extended several times and now runs through 1985.

Thereafter, Pescosolido was given forms with a handwritten OMB number in the top right-hand corner. But when he took an informal survey and found that his fellow growers' forms still did not have OMB numbers, he continued to refuse to submit them. His forms were discriminatory, he said.

The USDA took him to court. Last August, a U.S. District Court judge ordered him to fill out the forms required from February, 1982, onward. Pescosolido said he hadn't kept the necessary records. The USDA unsuccessfully tried several times to have the farmer held in contempt. Eventually, the judge ordered Pescosolido to reconstruct his records and retain new ones.

Pescosolido appealed the orders to the 9th U.S. Circuit Court of Appeals, which has not yet ruled. Last week, an appeals court panel heard his arguments against the USDA's attempts to subpoena his 1982 records.

While all this was going on, Pescosolido traveled to Washington a dozen times to talk to OMB officials. He'll be back again next week to talk about the navel orange committee's 14 new rules and the attendant paperwork burden.

"I understand the law was intended to relieve this kind of burden from the backs of the American people," he said yesterday. "I've attempted to use it to do what the preface and all the good words say. Unfortunately, I haven't been very successful, yet. And that's a massive understatement."