Because of an error in yesterday's editions, the nature of some challenges to petitions filed for the District's May 6 presidential primary was incorrect. Supporters of Lyndon H. LaRouche Jr. are challenging signatures filed by supporters of both President Carter and California Gov. Edmund G. Brown Jr.

The D.C. Board of Elections and Ethics adopted a ruling yesterday that could force supporters of President Carter's reelection totally off the ballot in half the city's eight voting wards at the May 6 primary election.

Besides threatening Carter's hopes of winning a majority of the city's 19 delegates to the Democratic National Convention, the ruling could leave California Gov. Edmund G. (Jerry) Brown Jr. entirely without backers on the District primary ballot.

The 2-to-1 ruling by the bipartisan elections board came on a technicality dealing with the number of signatures needed on official petitions to field slates of candidates in the primary.

The board spurned pleas by two leaders of the D.C. Democratic State Committee -- supporters of Carter and of his principal rival, Sen. Edward M. Kennedy, (D-Mass.) -- who insisted that the party's official election plan required only 1,000 signatures throughout the city. The elections board ruled that 1,000 are needed in each of two hypothetical congressional districts, each composed of four voting wards.

Carter backers collected and filed more than 1,000 signatures in each of the two congressional districts before the filing deadline last month. However, supporters of Lyndon H. LaRouche Jr., former head of the U.S. Labor Party who is seeking the presidency as a Democrat, have filed formal challenges to 650 Carter signatures in the first district. Those challenges, along with a similar challenge by Brown supporters, are being studied by elections board lawyers.

If the challenges are upheld, Carter would have no delegate candidates in voting wards that include the White House and Capitol Hill. The first district is composed of Ward 1, centering on Adams-Morgan; 2, the downtown area; 6, Capitol Hill, and 8, Anacostia and far Southeast.

Angered by the board decision, Robert B. Washington Jr., chairman of the D.C. Democratic Committee and a Carter supporter, threatened to take the issue to the D.C. Court of Appeals.

Washington was joined in his plea to the elections board for the 1,000-citywide-signature requirement by Walter E. Beach, chairman of a special convention delegate selection committee and a Kennedy supporter. Both insisted that the elections board was intruding on the Democratic Party's right to adopt its own delegate selection process.

Albert J. Beveridge III, a Democratic member of the board, denied this, saying the city has the legal responsibility to set the election process. He was joined in the vote by Virginia Moye, also a Democrat. Board Chairman James L. Denson, Republican, dissented, explaining later that he felt the board should take the word of responsible Democratic Party leaders as to the meaning of their delegate selection rules.