Prince George's County's quiet, white-haired school superintendent, Edward J. Feeney, yesterday abandoned his usual demeanor of professional detachment to join the school board's mud-slinging budget battle with County Executive Lawrence J. Hogan.

At a carefully planned news conference in Upper Marlboro yesterday morning Feeney described for reporters and television cameras what he said would be the "tragic consequences"of Hogan's proposed $13 million in cuts in the 1980 school board budget.

"They would curtail," said Feeney' "the county's ability to educate its young people."

Less than an hour later, Hogan struck back. In a 10-minute television interview that balloned into a press conference, Hogan called Feeney's statement "ridiculous" "absurd," "baloney," and "a game."

Feeney, said Hogan, had been enlisted in "a propaganda campaign by the school board" designed to create "a lynch-mob type of psychology" among citizens who would pressure the County Council to return the funds Hogan has slashed from the school budget.

The exchange of television-monitored rhetoric between the solemn Feeney and an almost ebullient Hogan marked the beginning of a new, more heated phase in Prince George's budget controversies, which have been heightedned this year by the voter-approved TRIM charter amendment limiting county tax revenues.

Feeney's press conference, school officials later said, had been carefully planned for over a week as part of a new strategy by the school board to rally public support against Hogan's budget cuts and his refusal to finance the board's new wage contracts with employes.

The idea, officials concede, was to "tone down" the personal attacks that some board members have recently made against Hogan and tro substitute the dignified Feeney as a professional school spokesman who could convince citizens that Hogan's cuts were indeed a threat to "quality and stability in our schools."

True to form, Feeney warned yesterday that Hogan's budget would force the schools to eliminate 704professional positions, largely through layoffs, that class sizes would increase "significantly," and that fourth-year language courses, advanced science and other specialized subjects might have to be eliminated from high schools.

Hogan was clearly not impressed. "I asked the people at home to look at the cuts I've made and see what effect any of them would have on the education of our children." he hold the television cameras. "I say it's minimal."

Feeney's press conference and the resulting confrontation yesterday came at the end of two weeks of steadily rising tension between the school board and Hogan.

The chain of events began on March 26, when Feeney and Hogan met to discuss Hogan's proposed changes in the board's $281 million budget.

In previous years, Feeney, who became school superintendent in March 1976, used such sessions with former executive Winfield M. Kelly Jr. to work out or resolve major funding issues fro the schools before the county budget was even released, school officials said.

But this year was different, Feeney and Hogan, sources said yesterday, quickly became involved in a dispute over the new two-year contract Feeney helped negotiate with county teachers. The contract calls for a wage increase of 4.7 percent next year, but Hogan has included only enough money in his budget for a 3 percent increase.

Feeney's distress grew during the week as Hogan reiterated his intention not to pay for the wage increases for teachers. Meanwhile, Hogan and school board Chairman Norman H. Saunders became involved in a public war of taunts in which Saunders, invoking "the great seal of the state of Maryland," suggested that the office of county executive should be abolished.

Yesterday's press conference by Feeney was set last Thursday during a school board executive session. Feeney urged the board to ratify its contract with teachers that evening, even though Hogan had already said he wouldn't pay for it.

Some board members, in turn, uged Feeney to broadcast his budgetary worries to the public."The level of inflammatory rhetoric by board members had been rising every day," said one board member yesterday. "The strategy was to tone down the situation by having Feeney give a serious, professional analysis of the problem."

Meanwhile, board members agreed to divide among themselves the various cuts Hogan had proposed and research them separately, so that each board member could focus on a different cut in the budget when the people besides the teachers. Feeney wanted to get the message across to parents that the schools were really threatened."

Aubuchon wrote the strtement following the meeting, and yesterday, Feeney quietly read it. It was after he finished his speech however, that County Council hears testimony on school funding.

School staff members reseached the effects of the cuts, and last Monday, Feeney, deputy superintendent Allan I. Chotiner, assistant superintedents Edward Felegy and Eliot Robertson, budget director Frank Platt, and school spokesman John Aubuchon met to decide on how, exactly, Feeney would take on Hogan.

"We made a deliberate attempt to be low-key and stay away from personalities," said an official familiar with the meeting. "We want to appeal to the superintendent made his strongest remarks.

"you know, it's always been very important to us that our students are able to get jobs and go on to college," Feeney said.

"Now, if they are going to be pushed out and turned into dropouts, I don't think that's the best interest of the county," he said.

Later, asked if he thought his escalating public debate with Feeney and the board was necessary, Hogan has simple response: "It comes with the territory."