An article yesterday incorrectly said that Montgomery County School Board President Eleanor Zappone voted to ban smoking by students on high school grounds. She voted against the proposal, which failed.

Marian Greenblatt, leader of the embattled conservative majority on the Montgomery County Board of Education, failed to show up yesterday for the postprimary board meeting, and her colleagues, battered but still in contention for control of the board, lost a key vote.

Greenblatt, who lost the Republican nomination for Congress on Tuesday to former board member Elizabeth Spencer, could have cast a tie-breaking vote on a motion by conservative board colleagues Suzanne Peyser and Carol Wallace to ban smoking by students on high school campuses. The proposal failed, 3 to 3.

Board member Joseph Barse, who usually votes with the Greenblatt-led faction, voted against the motion, saying it was unenforceable.

Barse and Wallace finished fifth and sixth behind four liberal candidates in Tuesday's balloting for the school board. The primary field of 15 was reduced to eight nominees, from which four board members will be elected in November.

School Superintendent Edward Andrews supported the smoking ban, as did board President Eleanor Zappone, another Greenblatt ally, but an 11-member committee, composed of principals, parents and students, had recommended, by a 9-to-2 vote, keeping the present policy, which permits smoking in specified areas.

So while yesterday's vote could not be counted as a test of the conservatives' strength, the absence of Greenblatt illustrated the thin margin by which many issues are decided by the current board. Zappone announced at the start of the day-long meeting that Greenblatt, who has made no public statement or appearance since her defeat, "may or may not join us."

Unlike past weeks, when many of the 15 board aspirants in the primary copiously scribbled notes on board actions, only Jim Cronin, a part of the winning EDPAC slate, showed up yesterday.

Unlike Spencer, Greenblatt did not give up her seat on the school board to run for Congress, so despite her defeat in the primary, Greenblatt can remain on the board for another two years.

But Spencer's victory, in the face of a late start and little money, combined with the relative poor showing by Barse and Wallace against four candidates determined to oust them, was seen as an indication that only a radical shift in voter sentiment could save the board's conservative majority from being toppled Nov. 2.

Before Tuesday, Barse was predicting that he and two slate members would survive the primary, but his running mates finished far back in the pack. After the votes were counted, Barse, who led the field in the 1978 general election, said "maybe nothing can be done . . . . Maybe the solution is to contact people who don't feel that way and didn't vote in the primary."

The vote "reflects strong organizational muscle," conceded Barse. "Very good organization of people in the precincts, spreading the word. It's a classic case of strong political organization having an impact."

Paul Clark, the county's Republican chairman, said the team of candidates who led the balloting -- Marilyn Praisner, Odessa Shannon, Cronin and Robert Shoenberg -- "ran a very professional campaign. They outorganized and outstrategized the incumbents."

Shannon, the only black candidate, raised the most money, supplying the bulk of the $11,000 EDPAC spent for mass mailings and purchase of a sophisticated series of computer printouts that showed every campaign contributor and who they supported since 1978.

Royce Hanson, a former Democratic congressional and county executive candidate, said, "Montgomery County . . . people are very moderate and cautious and they like their candidates to be progressive and reasonable. It would seem that the votes indicate a clear repudiation of the Greenblatt board."

The other two nominees, Tim O'Shea and Barry Klein, who ran as part of a moderate slate, finished seventh and eighth.

Incumbent Wallace, the only candidate to run alone and survive the primary, was in good spirits at yesterday's board meeting. Formerly closely allied with Greenblatt and Barse, she has taken steps ot put distance between herself and the Greenblatt faction in recent months. Her optimism was buttressed by the fact that she finished fifth in the 1978 primary, but came back to finish second in the general election that year.

"You have to get out there and get your message across to the electorate as best you can," Wallace said. "I'm running on my independence, my integrity and my record." She and Barse also are counting on Klein and O'Shea siphoning votes from the Shannon-Shoenberg-Cronin-Praisner alliance.