The Chicago Cubs won’t have one of their top starting pitchers for the remainder of the season.

Cubs manager Craig Counsell announced on Tuesday that right-hander Cade Horton will have season-ending UCL surgery.

Horton was injured in his second start of the season and was already on the 15-day injured list as the team investigated its options.

Horton was the runner-up for the National League Rookie of the Year award last season after posting a 2.67 ERA with 97 strikeouts in 22 starts to help the Cubs make the playoffs.