The incorporation of green manures of grain crops including wheat and sudangrass have been shown to reduce root rot diseases and their damage to beans and other vegetables. In addition, it was recently demonstrated that the incorporation of green manures of sudangrass suppresses the root-knot nematode and its damage to vegetables. The mechanism of nematode suppression was determined to be due to the production of toxic metabilites, including the hydrogen cyanide gas produced during decomposition of sudangrass tissues. Thus, this 2-year project was conducted to evaluate the efficacy of green manures of sudangrass and wheat with and without a surface seal against root rot pathogens and their damage to beans.