Concern over the long-term ecological effects of synthetic agricultural chemicals has led to increased efforts in the search for natural products (Cardellina, 1988). Allelopathic chemicals found in natural products may be used directly as herbicides and to develop new classes of synthetic herbicides based on natural chemicals (Narwal, 1996). Corn gluten meal (CGM) has been identified as an effective natural preemergence herbicide for use in turfgrass and other crops (Bingaman and Christians, 1995; Christians, 1993; Nonnecke and Christians, 1993).