Diamondbacks manager Torey Lovullo said Monday that Castro (shoulder) will begin his throwing program this week, Theo Mackie of The Arizona Republic reports.
Castro landed on the 15-day injured list Tuesday -- retroactive to April 21 -- due to right shoulder inflammation. He posted a 5.19 ERA and 1.50 WHIP over 8.2 innings prior to being placed on IL. The 29-year-old right-hander is eligible to be activated May 6, but he could stay on the IL past that date depending on how he progresses in his throwing program.