The commercial development of microbial bioherbicides requires the availability of low-cost production methods. The use of liquid culture fermentation is generally considered necessary to achieve this goal. Our strategy for optimizing liquid culture media is based on using defined nutritional conditions. Specific changes are made in the nutritional environment of the medium and the effect of these changes is assessed in terms of propagule yield, efficacy, and stability of the bioherbicidal agent. Liquid culture studies with the fungus Colletotrichum truncatum have demonstrated that nutrition impacts not only spore yield but also spore efficacy in controlling the weed hemp sesbania. Nutritional conditions were identified which suppressed sporulation and promoted the production of high concentrations of C. truncatum microsclerotia in liquid culture. Microsclerotia of C. truncatum (particle size range = 180 μm to 425 μm) showed promise as bioherbicidal propagules due to their stability as a dry preparation and their efficacy in controlling hemp sesbania when used as a soil amendment. By understanding how nutrition impacts propagule formation, yield, efficacy, and stability, rational approaches can be taken to develop submerged culture production methods for microbial biocontrol agents. Breakthroughs in these areas should allow numerous promising bioherbicidal agents to become commercial products.

Florida beggarweed is native to the Western Hemisphere but is naturalized around the world. During the last century, the mechanization of agriculture has transitioned Florida beggarweed from an important forage component to a weed of significance in the coastal plain of the southeast United States. This herbaceous annual is naturalized and found in fields and disturbed areas throughout the southern United States. The characteristics that made Florida beggarweed a good forage crop also make it a formidable weed. This review describes the importance of Florida beggarweed as a weed in the southern United States and the taxonomy of this species and details the distribution throughout the world and within the United States. The ecology of Florida beggarweed and its interactions with crop plants, insects, nematodes, and plant pathogens also are summarized. Finally, management of Florida beggarweed in agricultural systems using cultural practices and herbicides is reviewed.