The world used to be a shucker's oyster. But not anymore.

George Hastings, crowned U.S. oyster shucking champion in St. Mary's County last weekend, won't be going to Ireland next fall as the American entrant in the world competition because his title, local officials claim, has been pried from their control by a big corporation eager to cash in on their prized idea.

For the past 23 years, the U.S. oyster shucking champion--the best and fastest at opening oyster shells and extracting the tasty morsel inside--has been chosen at the St. Mary's Oyster Festival, an annual homage to the fall oyster season. The yearly competition made Leonardtown, the county seat about 60 miles south of the District and site of the festival, the mecca of American oyster shucking.

But Guinness, the multinational company that brews the famous beer and is the longtime sponsor of the festival in Galway, Ireland, has apparently muscled St. Mary's champions out of the international competition. Galway festival officials say that beginning next fall, the American contestant in their world championship will have to come from events sponsored by Guinness--perhaps even from New York City.

"Yes, it sounds like what it is--a big guy taking advantage of the little guy," said Jane Sypher, a onetime St. Mary's oyster king (they're called king whether the winner is a man or a woman) and former president of the Lexington Park Rotary Club. The club sponsors the St. Mary's Oyster Festival each year, and the 33rd edition drew a crowd of about 15,000 from the Washington region last weekend.

"It's disheartening," Sypher said. "It's the big corporate entity looking at the bottom line."

Guinness has sponsored the Galway festival for 45 years and two years ago decided to start its own U.S. festivals--complete with a shucking competition. Before long, the idea emerged to pick an American Guinness champion to advance to the competition in Ireland. The Guinness festival in New York City has become one of the firm's biggest and most successful and was held Oct. 2 for the second year. Shuckers from the city's most glamorous oyster bars--Balthazar, Blue Ribbon and Docks--competed.

Guinness officials are doing their best to play down any conflict with the St. Mary's festival.

"We made a request to the Galway festival committee about having a champion [from corporate-sponsored events] represented in Galway. The committee made the decision," said Howard Pulchin, spokesman for Guinness Bass Import Co. in Stamford, Conn.

"What we'd love to do after this fall is sit down with St. Mary's and see how we can work together on this," Pulchin said.

Smaller "feeder" oyster festivals in Alabama, Connecticut, Florida, North Carolina, Virginia and Washington have long recognized St. Mary's County as the place to seek the national crown.

"The place to go to compete for the U.S. championship is not New York City but Leonardtown, Maryland," said Hastings, the newly crowned U.S. oyster king who is a highway engineer from Severn.

Hastings, 44, said he's dreamed of representing the United States in Ireland since he first learned how to shuck oysters at age 15.

"I think and I hope that both sides will come together, and I'd get to represent the U.S. in Galway," he said.

The idea of a New York City venue for the national oyster shucking championship is not sliding down easily with diehard shuckers.

"I hate it. We've always been in Maryland and people there have always been good to us," said Cathy Milliken, a former champion from Supply, N.C., who went to Ireland in 1987. "Why change a good thing?"

St. Mary's County festival officials have been negotiating quietly with Guinness and festival officials in Galway for more than a year. But Paul Faller, deputy chairman of the Galway Festival, noted pointedly in a letter to St. Mary's sponsors that Guinness is "our major sponsor and he who pays the piper calls the tune." Ten days ago, Sypher received word from the chairman of the Galway festival that the decision stands to keep the St. Mary's champion out of the Galway festival next year.

"Our initial response was: Maybe Guinness will sponsor us," Sypher said.

But word came back that "Guinness was not interested in sponsoring us," Sypher said. "Our festival was too family-oriented."

The St. Mary's festival has activities and exhibits aimed at youngsters, while Guinness is more interested in the "21-and-over crowd," she said.

"I think St. Mary's is being viewed as not being a very good venue for beer drinkers," Sypher said. But she indignantly declared that festival-goers here are known to down a pint or two, noting that $10,000 worth of American beer was sold during the recent two-day festival.

Organizers of the St. Mary's competition have said they are "prepared to make a legal challenge" over international trade infringement issues involved with the use of "U.S. shucking champion," or variations of it.

"What Guinness is looking to do is promote Guinness in America," Sypher said. "We're a community organization that's doing this to foster an appreciation of the watermen and an industry."

CAPTION: Wayne Copsey may be the last U.S. champ chosen at the St. Mary's Oyster Festival to compete for the world title.

CAPTION: "It's disheartening," says Jane Sypher, a onetime oyster king.