Pete Seeger's new book, "Carry It On!," is a labor of love reflecting a love of labor.

"I thought it would be a great pity if 1986 came and went without people remembering the Haymarket affair in Chicago 100 years ago," notes Seeger, recalling one of America's most notorious labor confrontations. Seeger sent out a call through his column in Sing Out for musicians to learn some of the old union songs.

"That style is kind of passe' musically, but some of them are remarkably good songs that have lasted a long time," he said.

A committee ended up gathering some 300 of the songs with the idea of mimeographing them for distribution, until one member, Bob Reiss, "to everybody's surprise, got Simon and Schuster to agree to publish the book" in an expanded form. "It became a picture book as well as a song book," with connective historical text.

"It's not just union songs," Seeger notes, "but goes back to the American Revolution and the story of the American people struggling in one way or another to improve their condition."

In this decade Seeger sees "a gradual but steady increase of a wide variety of topical songs. Some are hymns, very gentle spiritual-type songs; some are hilarious satires; some are more related to jazz or ethnic styles."

And some are sudden revisions. "In 1940 Woody Guthrie was singing for oil workers, with me tagging along, and the wife of the organizer said, 'Woody, all the union songs seem to be about the men doing this, brothers doing that . . . Why don't you write a song for the women in the union?' The meeting we were singing at had a lot of women and children, babes in arms. Next morning, I found stuck in the typewriter these new words to the old tune of 'Redwing':

'There once was a union maid/She never was afraid/Of goons and ginks and company finks/Or deputy sheriffs who made the raid . . ."

That's one of the songs in "Carry It On!" and probably one of the songs Seeger, Earl Robinson (coauthor of "Joe Hill") and such local labor voices as Hazel Dickens, Joe Glazer and Saul Schneiderman will sing Saturday at Lisner Auditorium. The concert, presented by an alliance of 14 major unions, is a benefit for the Labor Heritage Foundation, an organization trying to raise awareness of workers' culture, both within the labor movement and with the general public. Seeger will be autographing his book from 5:30 to 7 p.m. Friday at Common Concerns, 1347 Connecticut Ave. Music Forum

More than 90 panelists have signed up for the first Baltimore, Washington and Virginia Music Business Forum, to be held Saturday at the Sheraton Hotel in New Carrollton. The daylong event, organized by the local Liaison Records, will feature morning and afternoon panels on radio, retail/marketing, clubs/promoters, attorneys, record labels (major and independent), merchandising and more. Representatives from local radio stations and trade papers and workers in dozens of music-related businesses will be participating in the workshops, which will occupy six ballrooms.

"It's to promote the music industry in this marketplace, and to help educate the community," says Liaison's Becky Marcus. "A lot of people have been calling us with questions that hopefully will be answered at this forum."

Admission is $25 at the door, $20 with preregistration. For more information, call Liaison at 937-6161. Sisterfire's Preparation

Sisterfire, the outstanding festival of women's culture that has drawn throngs to Takoma Park the last four years, will take a hiatus this year while its sponsoring organization, Roadwork, restructures, redefines its goals and raises funds for an expanded cultural resource center.

After eight years of producing and booking local concerts and national tours, lectures, workshops and other events reflecting the complexity and diversity of women's culture, Roadwork may be excused for catching its breath. After all, Sisterfire grew in four years from a one-day, single-stage, eight-performer event to a two-day, three-stage, 80-performer extravaganza taking much of the year to prepare. Pretty good for an organization that started in the basement of an alternative record store.

"Progressive cultural workers have to have a long-term approach if we're going to survive through the era of Gramm-Rudman," says Roadwork Director Amy Horowitz. "We're in this for the long haul, and we need to take the time to stabilize Roadwork as an institution that can truly be of service to a growing international cultural movement."

Though Sisterfire drew young and old, gay and straight, female and male, it may have been too successful for Takoma Park, attracting crowds of 6,000. When the festival returns in 1987, it will be at a location in the District. Before then, Roadwork will try to raise $100,000 to develop its resource and training center.

In the meantime, highlights of the 1984 festival can be heard on "Sisterfire," a recent Redwood Records release. Among the performers: Holly Near, Ronnie Gilbert, Moving Star Hall Singers, Reel World String Band and locals Cathy Fink, Alicia Partnoy, Sweet Honey in the Rock and Flora Molton.