Rucker was placed on the 15-day injured list due to turf toe Thursday, retroactive to May 17, Tim Stebbins of NBC Sports Chicago reports.
Rucker has made eight relief appearances for the Cubs this year, and he's posted a 4.20 ERA and 1.20 WHIP in 15 innings. The right-hander will be sidelined until at least early June due to his toe injury, but it's not yet clear whether he'll be able to return once he's first eligible.