Turner said it's not known yet whether Cason, who fractured the finger in defending a pass during practice Sunday, will be available for the team's first two preseason games.
"I'm a little upset," Cason told The Union-Tribune on Monday. "It's a hiccup ... I'll be back out there soon."
"Cason will be fine," Turner said.
"I like everything that Gilchrist has done," Turner said.
"One thing that's jumped out -- and I think it's a starting point for corners -- is he's shown he's very physical. He's come up and filled the run. He's been very aggressive."
Veteran Dante Hughes, who can start practicing on Thursday, also will get extra work.
A first-round pick in 2008, Cason is coming off his first season as a full-time starter. He started 15 games last season, with 67 tackles, by far his most-productive season since being drafted by San Diego in the first round of the 2008 NFL Draft.
The Union-Tribune also reported that second-year running back Ryan Mathews missed practice with "soreness" but should return to the field in a couple days.
The Associated Press contributed to this report.