Lewis Vaughan took just a minute to toast the new manager, netting after good work from Nathan Flanagan and, by half-time, it was 4-0. Flanagan added the second after just 12 minutes then collected his second after 33 minutes and four minutes later Kevin Nisbet made it four with his tenth of the season.
Calum Gallagher headed a consolation goal for Dumbarton from an Iain Russell cross with 20 minutes left but Liam Buchanan made it 5-1 with three minutes left.
Arbroath held on to their four-point lead at the top with a come-from-behind 3-1 win over Airdrieonians.
Airdrie took a deserved lead midway through the first half when Joao Vitoria scored from close range. But Gavin Swankie equalised six minutes into the second half and Colin Hamilton then headed the leaders in front before Ryan Wallace made sure of the points with a third with five minutes left.
East Fife moved into third place with a 2-0 win over Stenhousemuir thanks to goals from Craig Watson and Rory Currie while Montrose came back from two goals down to draw 2-2 with Forfar Athletic. Jamie Bain and Mark Hill edged Forfar in front but goals from Graham Webster and Danny Cavanagh with 15 minutes left earned a share of the points.
Brechin City and Stranraer shared a 1-1 draw. Callum Tapping put Brechin ahead but Luke Donnelly equalised late on.