Guest conductor Ken-David Masur was two for three at Sunday afternoon’s concert of the Portland Symphony Orchestra at Merrill Auditorium — a delightful Bartok Divertimento for String Orchestra; a spectacular Copland Concerto for Clarinet and Strings, Harp and Piano; and a plain vanilla version of Mozart’s “Jupiter” Symphony No. 41 in C Major (K.551)

The Bartok Divertimento is the most accessible of that composer’s work and was made even more so by the clarity and balance of Masur’s direction. He conducts without a baton, but achieves even more precision with his fingertips, as if he were playing a gigantic organ.

The string sound was rich and full from the first bar, with a lively but delicate one-two-three rhythm, and bursts of folk-influenced melody.

The second movement, sometimes thought to be Bartok’s depiction of the Nazi takeover of Hungary, contains, like the score of “Jaws,” a menacing rhythmic pattern in the bass, but is infinitely more subtle. In its development, it seemed like wraiths of the dead, swirling over an armored column.

After that, the third movement, Allegro assai, was cheerful and even humorous, showing Bartok at his most inventive, with a fugue, a difficult violin solo perfectly articulated by concertmaster Charles Dimmick, and a charming pizzicato section.

The Copland concerto is a wondrous thing, written to show off the clarinet virtuosity of Benny Goodman and not to be taken all that seriously. Goodman would have been envious of its performance by Ricardo Morales, principal clarinetist of the Philadelphia Orchestra.

I have never heard clarinet playing like this, bright and perfectly phrased with staccato yet liquid runs like bird calls. Morales is good in every register and can hold a fortissimo note for as long as it takes.

The concerto has a Latin flavor, but begins with a slow waltz reminiscent of Ravel. The second movement, to which a brilliant cadenza serves as a bridge, begins and ends with the famous clarinet run that opens Gershwin’s “Rhapsody in Blue.” In between there are plenty of references to both Latin music and jazz, with a call and response section that was worth the price of admission in itself.

Mozart’s stately “Jupiter” Symphony (No. 41 in C Major, K. 551) was well played but never seemed to come alive, perhaps because of the highly contrasting works that had gone before.

Christopher Hyde’s Classical Beat column appears in the Maine Sunday Telegram. He can be contacted at:classbeat@netscape.net