PHOENIX — Mark Appel, a Phillies prospect and former No. 1 overall pick, underwent season-ending surgery Wednesday to remove a bone spur from his right elbow.

Appel, who turns 25 next month, was on the minor-league disabled list with a shoulder injury. The Phillies discovered an elbow injury when Appel restarted a throwing program as part of his rehab from the shoulder ailment. The team does not believe Appel has an additional shoulder problem.

But Appel will lose crucial development time. The team said his expected recovery will take four to six months. He should be ready for spring training in 2017.

Acquired from Houston as part of the Ken Giles trade last winter, Appel had a 4.46 ERA in eight starts for triple-A Lehigh Valley. He struck out 34 and walked 20 in 38 1/3 innings.

He had been on the disabled list since late May. The Phillies will have to add Appel to the 40-man roster this fall or risk losing him in December's Rule 5 draft. Appel was the No. 1 pick in the 2013 amateur draft by the Astros.

Moniak debuts

Mickey Moniak, the Phillies' No. 1 pick, singled in his professional debut Wednesday with the Gulf Coast League Phillies.

Moniak, 18, batted second as the designated hitter. He struck out in his first two at-bats, grounded out in his third, and collected a run-scoring single in his fourth. He drew an eighth-inning walk to conclude his afternoon.

The Phillies could keep Moniak in the GCL for the duration of his first season. That is what the club did last summer with Cornelius Randolph, a high school hitter they selected with the 10th pick in the 2015 draft.

Randolph batted behind Moniak on Wednesday. The 19-year-old outfielder, sidelined by a nagging shoulder injury, appeared in his first game since April 21. He walked and lined out. Randolph played 3 1/2 innings.

Extra bases

The Phillies swept Arizona at Chase Field for the first time since June 5-7, 2006. The winning pitchers in that series were Aaron Fultz, Cole Hamels and Ryan Madson. … Triple-A Lehigh Valley catcher Andrew Knapp, outfielder Cam Perkins and veteran reliever Edward Mujica were named International League all-stars. … After a day off Thursday, the Phillies will face the defending-champion Kansas City Royals at Citizens Bank Park. The scheduled matchups are Jeremy Hellickson vs. Kansas City's Ian Kennedy, Aaron Nola vs. Danny Duffy and Vince Velasquez against Yordano Ventura.