Advocates for the poor must dispel myths about welfare in order to stop further federal budget cuts, a group of 150 Maryland social workers were told yesterday in Annapolis.

"The rich college students collecting food stamps haven't existed since 1976 when Congress ended them for most students," said Nancy Amidei, director of the Food Research Action Council, a Washington lobby group which alerted the public to the Reagan administration proposal to count ketchup as a vegetable in school lunches.

"But the tired example is still trotted out as a reason to supply food stamps to only half of the poor and near poor in this country . . . . Eighty percent of the recipients are little kids, the elderly and the disabled."

Federal budget cuts have eliminated or trimmed welfare and food-stamp benefits to 120,000 Marylanders in the last year, cuts that Kalman (Buzzy) Hettleman, head of the Maryland Department of Human Resources, called "unprincipled and unfair."

Amidei said the nationwide votes for an end to nuclear weapons and the election of an unusually large group of new Congressmen (81), the majority of whom defended social programs, signifies a new mood against further cuts.

She praised efforts by the group -- a four-year-old coalition of social organizations called Welfare Advocates -- in defeating a measure last session which would have required many welfare recipients in the state, mostly young mothers, to work.

Amidei proposed, instead, a "Leisurefare" program for boat and airplane owners to work for $3.35 an hour to pay off federal services they receive from the U.S. Coast Guard and the Federal Aviation Administration.

"Other forms of government benefits should be made equally as visible as the woman paying for groceries with food stamps," she said.

To support lobbying efforts before the state legislature and U.S. Congress, Welfare Advocates has compiled detailed descriptions of Marylanders receiving government help, showing that most welfare recipients are children and their mothers, rather than adults able to work fulltime.

Additionally, welfare payments in Maryland take up 5 percent of the state's $6.2 billion budget, much less than is assumed, said Linda Snyder, chairman of Welfare Advocates.

But that percentage is unlikely to increase during this legislative session, despite the sympathy of Gov. Harry Hughes, who has increased welfare payments 20 percent since a 1979 study found Maryland ranked 36th in the country in welfare spending and provided less than half of what a family of four needed for a minimal existance.

Although Welfare Advocates, and others, are pushing for a 6 percent boost in welfare payments in Maryland, which currently average $355 for a family of four, the governor's draft budget does not include any money for a welfare increase.

"We're trying very hard to get some increase in the welfare benefits," said Sheryl Lynch, a lobbyist with Catholic Charities in Baltimore. "But at the very least, with unemployment as it is, we're looking for the Maryland legislature to pass a jobs program to specifically help those on welfare."