The Arizona Diamondbacks have activated day disabled list.
Blum had been sidelined since July 25 with a fractured right pinkie and missed 35 games. It was his second stint on the DL this season, as he was also out from the start of the campaign until July 15 with a right knee problem.
The 38-year-old veteran enters Thursday's action just 3-for-15 in seven games this season with a homer and two runs batted in. He was 5-for-8 in three minor league rehab games.
Castillo had been out since July 30 with left shoulder tendinitis and missed 30 games. The 36-year-old lefty was 1-0 with an earned run average of 2.89 in 12 games this season before going on the DL.
The Diamondbacks also recalled right-handed pitchers Ryan Cook and Sam Demel from Triple-A Reno.
Cook struggled in four games earlier this season for Arizona, allowing four earned runs in 1 2/3 innings. He had a 2.12 ERA with six saves in 14 games for Reno and was 1-4 with 13 saves and a 2.25 ERA in 34 games at Double-A Mobile.
Demel appeared in 32 games for the Diamondbacks earlier this season before a demotion to Reno on August 1. He was 2-2 with a 3.60 ERA for Arizona.