Hours after rookie center fielder Hunter Pence was activated from the 15-day disabled list, Astros righthander Jason Jennings was placed on it Tuesday so he can have season-ending surgery to repair a torn flexor tendon in his right elbow. Jennings, whom the Astros acquired via trade last December because they were worried about Andy Pettitte's left elbow, has actually been dealing with elbow problems since last season with the Colorado Rockies. This is Jennings' second stint on the DL this year. He was also on it from April 9 through May 29 with elbow tendinitis . The Astros dealt starting center fielder Willy Taveras and righthanded pitchers Jason Hirsh and Taylor Buchholz to the Rockies for Jennings in one of the franchise's worst trades during the Drayton McLane era.