Dodgers plan to activate reliever Zac Rosscup against Angels

The merry-go-round that is the Dodgers bullpen will add another member this weekend. The Dodgers plan to activate left-handed reliever Zac Rosscup for the final series before the All-Star break against the Angels at Dodger Stadium.

The team claimed Rosscup off waivers this week; he was not able to crack the big-league bullpen of the Rockies, but he enticed the Dodgers to bring him to the majors.

Rosscup, 30, posted a 1.08 earned-run average in 10 outings with Colorado’s triple-A affiliate. He has a 5.30 ERA in 71 appearances since debuting with the Cubs in 2013.

Manager Dave Roberts indicated the team would observe Rosscup while they waited for left-handed reliever Tony Cingrani to recover from his shoulder discomfort. Rosscup missed a significant portion of this season with a wart on his left middle finger.

“Quick arm,” Roberts said. “He’s got a good slider, [fastball at] 93-95 mph. It’ll be an opportunity.”

Cingrani is one of several injured relievers rehabbing at Camelback Ranch on this road trip. He is joined by Pedro Baez (biceps tendinitis), Josh Fields (shoulder inflammation), Yimi Garcia (forearm inflammation) and Tom Koehler (anterior capsule strain).

Roberts views Baez as the closest to a return. He hoped Baez, Cingrani and Fields all can start facing hitters after the All-Star break. The confluence of injuries coincides with the approach of the July 31 trade deadline.

The Dodgers already intended to be active in pursuing bullpen help via trade. The team has remained engaged with Baltimore about shortstop Manny Machado, but some within the organization view the pitching staff as a greater area of concern. The uncertainty with so many members of the relief corps only increases the necessity to find fresh arms.

“These guys have got to be healthy,” Roberts said. “You can’t push them. Because they all want to pitch, but they’re not obviously healthy enough to pitch.”

SHORT HOPS: Roberts plans to visit the White House on Tuesday with Houston Astros manager A.J. Hinch and their families before the All-Star Game at Nationals Park. Roberts and Hinch became friends while working together in San Diego. Hinch organized the trip, Roberts said.

andy.mccullough@latimes.com

Twitter: @McCulloughTimes