White is being held back in extended spring training after suffering some minor dings in camp and will join Double-A Tulsa in the coming weeks, Jim Callis of MLB.com reports.
It's unclear what the exact issue is with White, and it's possible the Dodgers are simply being cautious with one of their better pitching prospects. Mitchell was excellent in his Double-A debut last season (2.57 ERA with 31 strikeouts over 28 innings), so he could quickly make the jump to Triple-A if he replicates that success early on this year.