LAST NIGHT’S PERFORMANCE of the Symphonie Plague No.3 by Ruthven Mophandle Heyser was disappointing: nothing was outlandishly poor, but the Duck Hollow Philharmonic is capable of better work. The bassoons, marked pianissimo in the score, nearly drowned out the rustling tissue paper, which is marked fortissimo. The Krummhorns were so badly out of tune that at one point a distinct effect of harmony was produced where, needless to say, none was intended. The concluding explosions were ill-timed and ruined the rhythmic effect of the finale. Much praise is due, however, to Miss Una Corda, the notoriously shy concert pianist, whose faint melodic tinkling was not audible at all.