Culter failed to finish their last home game of the season with a win, while the win helped Montrose finish third place for the season.
In a fairly uneventful match which matched the weather, both keepers failed to make a single save.
Rosco instead had to pull the ball out of the net in the 56th minute when Calum Rae blasted home from 12 yards after Montrose were awarded an extremely soft penalty.
See you all at Spain Park on the 7th May for the final match of the season.