PHOENIX -- Joey Votto, Scooter Gennett and Tucker Barnhart homered, helping rookie Luis Castillo to his first major league win in the Cincinnati Reds' 7-0 victory over the Arizona Diamondbacks on Saturday night.
Castillo (1-1) allowed three hits over 6 2-3 innings, striking out eight with a walk. It was his longest outing of the season.
Castillo, in his fourth career start, held the Diamondbacks hitless for the game's first three innings, then after giving up a single to Paul Goldschmidt retired the next nine Diamondbacks.
Votto drove in three runs.
The Diamondbacks managed only the three hits and lost their fourth game in the past five.
The Reds took control quickly, their first three batters of the game against Diamondbacks starter Taijuan Walker coming around to score. Billy Hamilton started the game with a walk, stole second base and scored on Zack Cozart's triple.
Votto's National League-leading 26th home run of the year gave the Reds a 3-0 lead with an out yet to be recorded.
Hamilton's two-out single in the fourth drove in Barnhart for a 4-0 lead, and Gennett's home run, a line drove over the right-field fence in the fifth, making it 5-0.
Gennett established a career high with his 15th homer of the season, and moved his hitting streak to seven games.
Walker (6-4) was done after five innings, allowing five runs and five hits with four strikeouts and three walks.
Castillo allowed two hits in the bottom of the seventh, the closest Arizona came to scoring. Wandy Peralta came on to get the final out of the inning.
Barnhart's second home run of the season came in the ninth off the Diamondbacks' Jorge De La Rosa.
Hamilton took over the major league lead in stolen bases with his second of the night Saturday, in the second inning. He finished with three for the game -- all in the first four innings -- and raised his total to 37.
The Diamondbacks held their annual alumni game before Saturday's game, with the red-jerseyed Diamondbacks defeating the team clad in throwback purple 3-0.
The Red Diamondbacks featured 1999 All-Star Matt Williams. The Purple Diamondbacks were led by former stars Luis Gonzalez, Mark Grace and Steve Finley.
Diamondbacks: OF Yasmany Tomas is still dealing with issues related to his strained right groin, and the injury has worsened. It could be some time before he is cleared for baseball activities. … RHP J.J. Hoover (right shoulder) threw in a simulated game Saturday at the team's Salt River Fields at Talking Stick facility.
Reds: RHP Homer Bailey (1-2) brings a 12.66 ERA over his first three starts of the season into Sunday against Arizona. He's 2-2 in his career against the Diamondbacks.
Diamondbacks: LHP Patrick Corbin (6-8) is 1-1 with a 3.48 career ERA in six games against the Reds.