Slipknot guitarist Jim Root has been forced to sit out dates on the Rockstar Energy Drink Mayhem Festival due to a burst appendix.

The band released the following statement before the tour's kickoff in San Bernadino, Calif. on Saturday (June 30):

"We're sorry to announce that our brother Jim Root [guitar] will not be performing with us at [Rockstar Energy Drink] Mayhem [Festival] today in San Bernardino due to serious health issues. Jim has been seriously sick for the past two weeks and went to the hospital last week where he was advised that his appendix burst a couple weeks before and that it could have been life-threatening. Jim is at home recovering and is awaiting surgery to have pieces of his appendix removed and hopes to join the tour as soon as he is able. SLIPKNOT will continue to headline the Mayhem festival and all other shows. We refuse to let our fans down and will not miss a single date. We will miss Jim greatly and our thoughts are with him. Jim sends his love to each and every one of our fans."

Besides Mayhem Festival, Slipknot are also getting ready to launch their own festival. The inaugural Knotfest will take place Aug. 17 and 18 and feature such artists as the Deftones, Lamb of God, Serj Tankian, Cannibal Corpse, Deathlok and the Dillinger Escape Plan.

Watch Slipknot's "People=Shit" Video