The Wolf Trap Opera began its month-long summer season last night at th for an opener it has come up with a real charmer. It is likely that few in the full house had ever heard Donhe Tutor's Dilemma" ("L'ajo nell'imbarazzo"). In fact, few probably had ever heard of it.

But remember, it i--"L'elisir d'amore" and "Don Pasquale"--that has held the stage most steadily among those 70 operas that he pralf of the 19th century. This one, his earliest hit according to the scholars, isn't on that level. But it is of a composer who had fully absorbed the lessons of Rossini in "The Barber of Seville." And in the places wherber" it sounds like some of the best of "The Barber," as in Donizetti's bracing second act trio between the tutor, his senior pupil and the pupil's betrothed, which could be the climactic crescendo of "The Barber's" glorious overture.

Donizetti was only 26 when he wrote it, and apparently it fell into obscurity as the subsequent works poured forth at floodtide. Conductor Richard Woitach, who directed a stylishly paced performance last night, came upon it several years ago and first presented it in San Francisco. Perhaps the opera doesn't belong in the Met repertory like the two later comedies, but it is poised and amusing, an almost ideal bel canto vehicle for apprentice companies like the Wolf Trap one.

It's a silly story, even for opera buffa. A father, Don Giulio, in early 19th-century Rome, is so aghast at the horrors that his sand Pippetto, might encounter if they ever came across members of the opposite sex that they are imprisoned in their home--even though Enrico is already 25.

A private tutor, Don Gregorio, is charged with isolucating them. And, as the action proceeds, he learns that the older one has already fathered a baby by a neighis having an affair with the housekeeper. How will Don Gregorio cope when Don Giulio finds out?

In last nigtar was the tutor, sung by baritone Dale Ganz, who has been singing opera buffa recently with the Texas Opera the most polished performer--a wry comic actor, a stylish musician and the possessor of a warm, flexible voiceMarie Pierson, as the young mother, came close. Her voice was not as rich as Ganz's, but she had a good sound, nice comic timing and the surest control of Donizetti's endless arrays of runs and all other ornaments.

Thilishly difficult to articulate. And one should not expect the kind of polish from singers like the Wolf Trap ones--with 16 soloists this year--as one would expect in this music at, say, Glyndebourne.

The other singers got off to slower starts. But Edward Randall, as Enrico, soon developed a nice lyric line. Brad Liebther, sounded good in the second act. Michael Brown, as the younger son, had less to do.

The pleasures of performing, and listening, in the intimate and air-conditioned Barns are considerable. Acoustics are so clear that just about everything is heard, including a large number of the words, in English. Thus it was possible to develop a fine sense of musical ensemble, with its resulting momentum, after some ragged moments early on.

The staging is ambitious, and ingenious. It turned out to be too ingenious, and complicated, for its own good. Singers spend too much time moving around the settings and props. But the most questionable element was a large square panel hung parallel to the stage to serve as a ceiling above the rooms. It was held by ropes at each corner. It also was lowered, by pulleys, to stand on its side as a wall in street scenes.

All evening one kept waiting for it to knock something over as it came down in the middle of the stage. But what finally happened was even worse. As the singers were lined up for their bows, someone backstage started lowering it, and it hit the star, Dale Ganz, in the head. He seemed unfazed. One hopes his head is not hurt so much that he cannot sing for the repeat tonight.