Queen of the South secured their play-off place with a 2-1 victory at home to Dumbarton.Second-half goals by Kevin Holt and Stephen McKenna put the promotion hopefuls in control and Donald McCallum's strike proved only a consolation for Dumbarton.Queen of the South threatened in the 14th minute when Danny Rogers produced a superb save to keep out a Derek Lyle header but it was a first half of very few chances.The deadlock was broken in the 55th minute when a cross from the right was flicked on and Holt tapped in at the far post.Dumbarton could have conceded a second soon after as Mark Wilson's weak backpass was picked up by Gavin Reilly but he was denied by Rogers before the rebound was cleared off the line.The home side doubled their lead in the 72nd minute as a curling shot from McKenna found the bottom corner.McCallum gave Dumbarton hope just four minutes after coming on when he produced a neat finish after playing a one-two with Mark Gilhaney but the hosts held on.