Dallas (12-8-5) got on the board in the 51st minute on a dicey penalty in the area. Akindele seemed to lose footing, but Javier Morales was whistled for a tackle. He then earned a booking for arguing the call. Akindele buried the penalty shot.
Salt Lake had a golden opportunity to tie when Juan Manuel Martinez was knocked down in the penalty area, but Morales hit the right post with the penalty kick.
Two minutes later, Castillo walked right through the Salt Lake defense and drilled one to the low right corner to make it 2-0.
The best chance in a scoreless first half came from Dallas' David Texeira at the top of the penalty area, but Nick Rimando's kick save was equal to the task.
Salt Lake (8-11-8) has lost four of five.