Technical Abstract: The widespread acceptance of reduced-tillage farming in cereal cropping systems in the Pacific Northwest (PNW) of the U.S. has resulted in increased use of herbicides for weed control. However, soil residual levels of widely used imidazalone herbicides limit the cultivation barley, which is more sensitive than wheat. In addition, increased severity of the root rot disease caused by Rhizoctonia solani is associated with reduction in tillage. Many crops exhibit altered disease responses after application of registered herbicides. In this study, the injury symptoms in barley caused by sublethal levels of two Group 2 herbicides, imazamox or propoxycarbazone-sodium were assessed, in factorial combinations with a range of inoculum levels of the root rot pathogen, Rhizoctonia solani AG-8. Both herbicides and pathogen had negative impacts on plant growth parameters such as root and shoot dry weight, shoot height and 1st leaf length, and interactions between pathogen and herbicide were detected. The results suggested sublethal levels of herbicides and R. solani could alter severity of injury symptoms, possibly due to the herbicide predisposing the plant to the pathogen.