The Fairfax County School Board has cut a third of its vocational education classes because of low enrollments, despite charges that the school system did a poor job of promoting many of the courses.

Of the 32 courses that will be dropped next fall, 21 have no students enrolled during the current school year.

Some school board members, however, blamed the low enrollments on the school system's failure to inform students of the courses.

Many of the subjects being eliminated haven't been listed in the rosters of available courses that are distributed to students, said David Sawyer, assistant superintendent for the vocational, adult and community educaton department.

"We had 21 courses where there was no student interest," Sawyer said. "There's no need to publish the offerings without student interest."

But unhappy board members said students can't be interested in something they know nothing about.

"We haven't really pushed these things," said board member James W. Kitchin, who opposed the cuts. "We need better recruiting."

Under new school board policies adopted along with the course reductions, all vocational programs must be advertised in county school schedules, beginning next school year.

"How can we justify cutting courses that had no enrollments even before these rules are implemented?" asked school board student member Ted Voorhees. "We have to have time to let it work. We're overreacting."

The reductions in the vocational education program drew loud criticism from county teacher organizations and vocational instructors, long sensitive to the status of manual trades courses in a school system that consistently boasts of a high percentage of college-bound students. One publicity brochure notes that 60 percent of the system's graduates go on to attend four-year colleges.

"People here think of vocational education as a dirty word," said one vocational education instructor. "Parents say, 'I don't want my kid taking any industrial arts.' "

Many vocational teachers criticize school guidance counselors for making little effort to direct students into vocational courses. The system's new policies require counselors to tour vocational facilities and become fully versed in course offerings.

But some board members and teachers say the new recruiting and course-advertising rules have come too late.

"While the plan attempts to correct the inequities," said Barby Halstead, executive director of the Fairfax Education Association, "it also proposed to delete certain courses due to reduced enrollments which have, in fact, resulted from exactly those inequities."

The board voted last week to eliminate 32 of the county's 102 vocational education classes, based on staff recommendations. Under pressure from teacher organizations and vocational instructors, however, the board rejected administration proposals to cut five other courses: record keeping, notehand/speedwriting and three barbering courses.

Although school administrators told the board the 37 courses orginally recommended in the reductions were incorporated in other course offerings, the board decided that in at least those five cases, no corresponding courses were available.

Courses that will be eliminated from Fairfax schools next year include business mathematics, tailoring, fashion design, small-business ownership, furniture marketing, needle crafts, catering specialist, introduction to horticulture, and marriage and parenthood.

Board member Mary E. Collier defended the cuts, saying, "We're going to have to be able to cull out courses every once in a while. We can't just add, add, add."

The course eliminations were part of an overhaul intended to streamline the county's vocational education program, according to Sawyer. He said the changes will not save the school system any money, however. About one of every five students in the Fairfax County Public Schools is enrolled in some type of optional home economics, trades and industrial arts or other vocational courses, according to school system reports.

Every high school in the county offers at least 27 standard vocational courses, and there are four vo-tech centers for more intensified training in skills areas.

Sawyer's reduction proposals included courses for which teachers were retained to teach only a half-dozen students in some classes. A teacher at Marshall High School is teaching three levels of barbering with a total enrollment of six, Sawyer's statistics showed.

But 53 students are enrolled this year in a data processing course the board agreed to slice from the the Edison High School curriculum. School administrators say students can be taught similar skills in computer science and proposed computer literacy programs in the school system.

Teachers and some board members criticized Sawyer and his department for drafting the proposals of course changes without first seeking their views.

Board Chairman Ann P. Kahn said at a meeting two months ago that there had been a "difference of opinion on how it should be handled." She acknowledged that board members were unaware of the plan until they began receiving telephone calls from irate teachers.