Blackstock is making steady progress from a knee injury and should be back after this weekend's clash at Middlesbrough.
"We are looking at another two weeks at least before Tyson is back," Davies told the Evening Post. "He is taking longer than expected to recover from his injury.
"Initially it was one of those that you thought might keep him out for eight or nine days but now it is looking like it will be at least a month by the time he is back.
"But Dexter is making steady progress. He is recovering and could soon be back in full training."