Queens controlled the game from the start with midfielder Trouten trying to link up with striker Bryan Felvis at every opportunity but Rovers were more direct, despite limited possession. Donachy fired in a right-foot effort which was cleanly held by keeper David Crawford.
However, Crawford was less impressive after 12 minutes when he allowed a hopeful long-range drive from Scott Chaplain to bounce past him on its way into the net.
Having scored twice against Rovers on their last visit to Hampden back in August, Ferry had three attempts on goal in quick succession although only the third, a fierce right-foot shot which was parried by keeper Allan Creer, posed any real threat.
Stephen Reid led a rapid counter-attack shortly before half-time but Queens were well on top in the second period, even before Donachy was sent off for a gruesome challenge on full-back Mick Dunlop.
As the pressure mounted on the visitors, Trouten's shot was saved and Ross Clarke hit the side netting before Ferry's glancing header made it 1-1.
Trouten should have pinched all three points with barely six minutes left but pulled the ball wide from point-blank range.