A southern governors' task force said yesterday that the South has the highest infant-mortality rates in the nation and recommended a series of state and federal actions to improve services.

These include a network of health services and improved welfare, plus a better food program and more Medicaid services for poor pregnant women and small children.

In 1983 the national infant-mortality rate was 10.9 per 1,000 live births (it dropped to 10.6 in 1984), but in South Carolina it was 15, in Mississippi 15.1, in Maryland 11.8, in Virginia 11.9 and in the District of Columbia 19.3.

One reason for high rates is that the southern states and the District have large numbers of poor blacks.

Because of poverty, lack of health care and poor nutrition, the black infant-mortality rate in 1983 was 20 per 1,000 live births.

After a year of study, a task force headed by South Carolina Gov. Richard Riley (D) concluded that "prenatal and infant care can save $2 to $10 for every dollar invested."

Riley said the South should make many of the improvements with its own resources.

The task force, set up by southern governors, included government and public health officials from throughout the South.

It recommended:

*In the Aid to Families with Dependent Children welfare program, states should voluntarily raise their standards so that any family with income lower than 50 percent of the federal poverty line would be considered in need. In 1984, the poverty line for a family of three was $8,277. Some states already have a need standard of more than half that figure, but the Riley report said some are below.

*Families with a father present but unemployed should be eligible for welfare and Medicaid. Many states pay only if the father is absent or dead.

*States should make all families below the poverty line eligible for a state maternal and infant-care Medicaid package. They should set up special indigent-care health programs for poor mothers and infants for whom they cannot afford to provide a full Medicaid package.

*The federal government should amend its welfare laws to help states provide the benefit packages described and expand grants for maternal and child health care.

*The federal government also should expand the special Women-Infant-Children (WIC) food supplements for children and pregnant women, which now cover only one-third of the eligible women and infants in the South.

*States should set up statewide coordinating councils on infant mortality, establish networks of health clinics for teen-agers, widen family-planning services, provide transportation to health centers for pregnant women and small children, make sure that every child has a "medical home" to provide ongoing care and require hospitals to admit all women in labor.

*States should provide substantially more health education in schools, religious and community groups and should do research on preventive care.