Washington Star managing editor Barbara Cohen will leave the newspaper to become director of news and information for National Public Radio on March 19.

"We just think it's dynamite," said NPR president Frank Mankiewicz yesterday. "She's been at the top of the list at all times."

Cohen, 33, joined the Star in 1968 as a copy desk trainee, became national editor in 1974, world editor in 1977 and last May was named managing editor for news. She has a master's degree from Columbia School of Journalism, but no pervious experience in radio.

Cohen, who has been discussing the position with NPR since last September, called her appointment "a tremendous opportunity for me... I'm very intrigued. NPR is a growing, thriving organization."

As director of news, Cohen will be responsible for such regular programs as "All Things Considered" and hourly news broadcasts, as well as special events and documentaries, congressional hearings and presidential press conferences. In addition, an as yet unnamed morning show, along the lines of "All Thing Considered," is expected to be on the air by Labor Day.

"With the addition of the morning show and the switch to the satellite in a year or year and a half," Cohen said, "the network will be putting out twice as much news."

Mankiewicz said Cohen's appointment to the $45,000-a-year position did not have to be confirmed or reviewed by the NPR board.

Murray J. Gart, editor of the Star, said yesterday, "Barbara is a primising young journalist with a fine future, and we are sorry to lose her. We wish her well in her new line of work."

Barbara Cohen is married to Washington Post columnist Richard Cohen.