The assist was the fourth of the season for Ferreira, who had missed the previous two games with a strained left hamstring.
"It was a great play by David," Castillo said through an interpreter. "On this play, David took the ball, he went at the defense and I just kept running by him. When he saw me open, he made a great pass for me and then I did what I know how to do, which is cut to the inside and I got a great shot for the goal."
San Jose nearly tied it in the 41st, but Victor Bernardez's 20-yard blast bounced off the crossbar.
Dallas had an opportunity to extend its lead just after halftime, but Jackson's booming shot from 20 yards out curled just wide of the right goalpost.
FC Dallas had another golden opportunity to go up by two in the 53rd after Castillo and Ferreira executed a perfect give-and-go that sent Castillo in on net alone before Busch charged out and made a nice sliding save on Castillo's shot from 10 yards.
Dallas lost striker Kenny Cooper in the 66th minute after an apparent head injury. Cooper was shoved by Bernardez out of bounds, and as Cooper went down, Bernardez's foot appeared to hit Cooper in the back of the head. After staying down for about two minutes he seemed a bit wobbly on his feet and was immediately helped to the locker room.
"I think he was knocked out a little bit, that's the information I have, and now we're getting information from our head specialist," said Hyndman.