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8/26/2013 10:17 P.M. ET

Astros shut down Appel, two other prospects

CHICAGO -- Right-hander Mark Appel, the No. 1 overall pick in June's First-Year Player Draft, made his final start of the season Sunday for Class A Quad Cities, which clinched a playoff berth in a 5-1 win. Appel allowed one run and four hits in five innings and won't pitch anymore this year.

The Astros are shutting Appel down after he threw 144 1/3 innings combined between Stanford and the time he spent with short-season Tri-City (five innings) and Quad Cities (33 innings). He went 3-1 with a 3.79 ERA in his pro debut.

"That's it for him in terms of games," Astros general manager Jeff Luhnow said. "He's going to remain with the team. They clinched a playoff berth last night in his last start, and it was a good thing for him to participate in that. He's not going to be pitching in games going forward."

Luhnow said the Astros have also shut down second-round pick Andrew Thurman and 2012 first-round pick Lance McCullers, both right-handers.

Thurman, drafted out of UC-Irvine, went 4-2 with a 3.86 ERA in 12 games (five starts) with Tri-City, striking out 43 batters in 39 2/3 innings.

"I didn't get a chance to see any of his starts, but they said the last two starts he was getting stronger and stronger and his velocity was getting into the mid-90s, and he was showing really exceptional fastball command," Luhnow said. "They were saying they can't wait to see what he shows up in Spring Training looking like. He made real good progress this summer."

McCullers, the 41st overall pick last year, went 6-5 with a 3.18 ERA and struck out 117 batters in 104 2/3 innings at Quad Cities, pitching all season at 19 years old.

"McCullers had an absolutely outstanding year," Luhnow said. "We couldn't have asked for anything more from him. He's really blossomed into an elite pitching prospect."

Bench to be fortified with September callups

CHICAGO -- The Astros are expected to add a few players on Sunday when they can expand rosters, but there doesn't figure to be a large-scale callup of players until the playoffs are over. Triple-A Oklahoma City is closing in on a playoff berth, and Double-A Corpus Christi has already clinched a playoff berth.

"We've talked about it internally," Astros general manager Jeff Luhnow said when asked about September callups. "As time goes on and they get ready to start the playoffs in Triple-A, we'll be able to identify exactly who will come right away. Then some guys that may come after the playoffs after they hopefully win it all."

Because the Astros are using a six-man rotation, they're carrying 13 pitchers, which means they only have three position players on the bench. Manager Bo Porter said that's not really an issue for him, especially with Sept. 1 only a few days away.

"We just felt more comfortable having the extra pitcher right now," he said. "Most of our guys that are playing are pretty much going to play every day. There aren't too many guys that we are going to hit for. With Sept. 1 right around the corner, we just figure we'll go with that construction. When Sept. 1 rolls around, we'll get some more guys added to the roster."

Worth noting

Astros owner Jim Crane provided a brief update Monday on the team's planned move to Palm Beach Gardens, Fla., for Spring Training. He said the city and county still have to approve a vote to spend money to help get a new facility built.

"The state has already put the money up, and then we're in the design phase and the vote should go in before the end of the year," he said. "I'm excited about that."

Brian McTaggart is reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.