Beverly Sills talks about the trials of running N.Y. City Opera. Also, a dazzling account of Schonberg's 'Erwartung'

Beverly Sills's first press conference in many a moon was everything one would expect from the feisty diva-turned-general director who now runs the New York City Opera.

Ostensibly, we were gathered to hear about the coming season, which opens in July, a first for the company. This has been arranged by placing the traditional spring season in the summertime, so that the usual two-section year will now move in an uninterrupted flow from July through November.

The focus of that season will be a Puccini Festival, to include a new production of ''La Rondine'' (Aug. 11), major revivals of ''Turandot'' and ''La fanciulla del West,'' and performances of ''La Boheme,'' ''Madama Butterfly,'' and ''Tosca.'' ''Turandot'' will feature the recently discovered full ending Alfano wrote after Puccini's death, which had been drastically cut by Toscanini before the world premiere.

But the season goes on with new productions of Gilbert and Sullivan's ''The Mikado,'' Massenet's enchanting ''Cendrillon,'' Handel's ''Alcina,'' and Floyd's ''Of Mice and Men.'' Major revivals also include Johann Strauss's ''Die Fledermaus,'' Janacek's ''Cunning Little Vixen'' (one of the company's finest recent efforts), and Richard Strauss's ''Ariadne auf Naxos.'' In all, it is a season that is much closer to what the City Opera is all about than has been the case in the recent past. Miss Sills also announced that Christopher Keene is now officially the music director of the company, making formal a relationship that augurs well for the future between the troupe and the energetic conductor, who favors new music.

A revival of the hugely successful production of Bernstein's ''Candide'' was to have kept the theater lit for six weeks this spring and kept members of the company working. But the orchestra voted the production down. Not surprisingly, therefore, Miss Sills opened the conference by saying that she had some things on her mind she wanted to get out in the open. She talked of ''the 'Candide' debacle,'' which turns out to be her first tangle with the new president of Musicians Union Local 802, John Glasel.

Clearly, Miss Sills is fighting mad over the incident. The problem as the orchestra players saw it was that the revival was being planned under a Broadway contract, at the insistence of James Nederlander, who was producing it as a favor to Miss Sills and the City Opera, on whose board he sits. An orchestra under a Broadway contract is smaller and plays two more shows per week than an opera orchestra. A salary difference was also an issue. Only 10 players would have been out of work, and Miss Sills thought that was better than having an entire troupe on the bread lines, but the union felt otherwise.

''I was astonished to find I was accused of gimmickry or villainy; I take exception to those words,'' the general director fumed. ''Mr. Glasel said the house was dark because of poor management . . . yes, poor union management.'' And now, of course, the house is dark, no income is being generated, and the company has to maintain the building in this fallow period.

The deficit, Miss Sills emphasized, is serious - $2 million - but not as high as rumor had it ($7 million). She noted that she had spent an inordinate amount of time trying to raise funds (she has succeeded in raising some $15 million since she took over the company), but it has exhausted and drained her. Now a management and fund-raising consultant firm will help her raise a $9 million endowment the company sorely needs.

There are three things, Miss Sills stated frankly, that she never shares - blame, credit, and desserts. To date, she noted, ''I have produced two enormous turkeys in my estimation: 'I Lombardi' and 'The Grand Duchess of Gerolstein.' '' Both shows received unfavorable to brutal reviews, and audience reaction was not much warmer. But she listed ''Attila,'' ''Cunning Little Vixen,'' ''Hamlet,'' and ''Les Pecheurs de Perles'' as being among her triumphs.

Ticket prices, she announced, will be up next year ($30 top), but subscribers still get a good break - ''it's our subscriber who is most important.'' She noted that the glorious production of ''Manon'' mounted for her during the glory days of her singing career in 1968 cost $140,000. To duplicate it today would cost $650,000. There will be no Los Angeles tour next year, and the yearly trip may no longer be feasible, given the costs involved in getting an entire company out to the West Coast. Miss Sills puts great store in the new touring company which was inaugurated this year.

She expects a tough but favorable outcome at the bargaining table this spring: ''If they devour us, they devour themselves,'' she noted. ''I think they'll be difficult negotiations. I think we will come to an agreement.''

As press conferences go, it was unusually lively, spontaneous, and interesting. Miss Sills is at her best in front of an audience - even one comprising both her greatest admirers and her severest critics. Explosive monodrama

Zubin Mehta is devoting some of his time this year to the presentation of some of Arnold Schonberg's most important orchestral works. So far, New York Philharmonic audiences have heard the symphonic poem ''Pelleas und Melisande'' (Op. 5) and earlier this month, the monodrama Erwartung (Op. 17).

Schonberg's ''Pelleas'' is not the evanescent, mysterious musical tale of Debussy or Faure, but rather an ultradramatic and explosive orchestral telling of Maeternick's lugubrious tale of fatal love. It is not often heard in concert. Unfortunately, the Mehta performance came at a slump period of the orchestral season, and was neither optimally well conducted nor played.

But last month the sort of dazzling performance one always expects from this orchestra came to pass. ''Erwartung'' is perhaps the ultimate study in decadence and insanity. The Lady - that's the only name she has - is wandering in the woods, and her rambling, self-directed musings and mutterings make up the text. It transpires that she may or may not have murdered her lover, but is utterly convinced that she has seen his body and wishes to do things even Salome would not have dreamed up.

Schonberg's particular genius was in turning such sordid, even distasteful stuff into a visceral, savage musical experience. The orchestral writing is ultravirtuosic and compellingly descriptive: Every emotion the Lady talks about is reflected in the score; every reference she makes to a mood, to some action, is expressed in the orchestra. Therefore, the success of a performance of this barely 30 minutes of unbridled insanity is very much in the hands of the conductor. If he makes the music too lurid, too raucous, the carefully calculated effects can be ruined.

And, of course, the soprano has to be a superb singing actress. Usually, ''Erwartung'' is the province of singers whose voices have known better days, but who know how to sell this sort of score interpretively. In New York, Hildegarde Behrens proved that a major singer with her instrument gloriously intact can make even more of this score. Where others have resorted to speech-song or mere yelling, Miss Behrens resorted to thrilling singing. Her dramatic approach was fearless, some might even say reckless, but she seared her performance into the audience's senses, and made this already dazzling account of this grisly work something for the legend books.