Palacios capped a three-run first inning with a two-run double, singled in his next two at-bats and walked in the ninth. The 26-year-old had his first three-hit performance in 61 major league games.
The last-place Cardinals had lost six of seven and were outscored 17-4 in the first two games of the series.
Zack Thompson (3-5) gave up two runs on six hits with five strikeouts in five innings. His outing was ended by a 92-minute rain delay with two outs in the top of the sixth.
Pirates starter Luis Ortiz (2-4) lasted just 3 1/3 innings, surrendering five runs on seven hits and five walks.
The Cardinals went ahead 3-0 in the first thanks to three hits and three walks. Alec Burleson got on with a bunt single and scored on Paul Goldschmidt’s single to right-center. After Nolan Arenado and Willson Contreras walked, Palacios doubled to right.
Arenado put St. Louis up 5-0 with a two-run double to left after Ortiz walked two more in the second.
Thompson hit Joe with the bases loaded in the third, cutting the lead to four runs.
Ke’Bryan Hayes made it 5-2 with a solo homer in the fifth, belting a fastball from Thompson 392 feet to right-center for his ninth of the season.
Pirates slugger Andrew McCutchen was 3 for 4 with a walk but was stranded at second after each of his three doubles.
BROTHER VS. BROTHER
Joshua Palacios, Richie’s older brother, had five RBIs for Pittsburgh in the series opener Monday.
Pirates: SS Oneil Cruz is no longer running due to left foot general soreness and his rehab from a fractured left fibula has “plateaued,” Pittsburgh director of sports medicine Todd Tomczyk said. ... RHP Dauri Moreta was optioned to Triple-A Indianapolis as a corresponding move to Ortiz being recalled from the taxi squad.
Cardinals: RHP Miles Mikolas (6-9, 4.55 ERA) is in line to start Friday's opener of a three-game series at Philadelphia.
Pirates: Have not announced a starter for Thursday's opener of a four-game series against the visiting Chicago Cubs.
AP MLB: https://apnews.com/hub/mlb
Wes Crosby, The Associated Press