Matt Garza worked six shutout innings Thursday night for Triple-A Des Moines, allowing two hits, walking none and striking out six in a 1-0 win over Tucson. Barring the unexpected, he should make his 2013 Cubs debut next week. “I don’t need another start down here,” Garza said, according to the Des Moines Register. “There’s no reason for me to stay in the minor leagues.” Assuming Garza, who is recovering from a strained left lat muscle, comes back as scheduled, he’ll have a little more than two months to work before the July 31 trade deadline, when the Cubs must decide whether to deal him or hang on to him in the hope of signing him to an extension. Carlos Villanueva, who is slotted to start Tuesday, is the most likely guy to lose his spot in the rotation. Manager Dale Sveum hasn’t ruled out a six-man rotation, but that seems very unlikely for the long haul.