Green manures of a number of rotational and cover crops have been shown to effectively suppress the severity of root diseases and improve crop yield. We have recently documented that sudangrass incorporated as a green manure is effective in suppressing the root-knot nematode on vegetable crops. The principal mechanism involved in the observed suppression was shown to be due to the production of gaseous toxic compounds during the decomposition of the green manures in soil. This project was conducted to evaluate the effectiveness of green manures of sudangrass and wheat in suppressing root rot diseases of beans, thus the development an environmentally compatible management strategy for this important disease.