Next year, the Marshfield Fair will turn 150. Planning has already begun for the milestone, but its organizer says there will be no reprisal of a favorite event from the past: horse racing. Leonard LaForest, president of the Marshfield Agricultural & Horticulture Society, which puts on the fair, said state regulators in the early 1990s gave permission to a commercial track to hold races during the Marshfield Fair, telling the town to move its races to September. That didn’t work for organizers, as attendance would have suffered and the noise from the races would have disrupted nearby schools, LaForest said. So they opted to end horse racing in Marshfield, with the last race taking place in 1991.