Knock out roses are being used all over for landscaping purpose because of their easy upkeep and size makes them great landscaping roses. However, Kansas State University has reported that they are susceptible to Rose Rosette. This virus like disease is a form of Aster Yellow phytoplasma. Unfortunately,  it does not have a treatment and the best course of action is to remove the plants and send them to the landfill in a sealed trash bag.