Submitted to: Proceedings, IOBC
Publication Type: Proceedings
Publication Acceptance Date: May 26, 2002
Publication Date: N/A
Technical Abstract: Numerous fungi show excellent potential for use as biocontrol agents due to their ability to selectively infect and kill a variety of weedy and insect pests or their ability to antagonize or exclude plant disease-causing organisms through parasitism or competitive exclusion. The lack of suitable methods for economically producing stable, effective fungal propagules continues to impede the commercial use of these biocontrol agents. Selecting fungi for use as biocontrol agents and for concomitant amenability to liquid culture production requires an understanding of how the organism carries out its biocontrol function and in what environment it will be used. For use as a foliar spray or in post-harvest disease control applications, production of the fungal biocontrol agent as yeast or yeast-like propagules is advantageous. The potential to control soil-borne plant diseases with fungal biocontrol agents is greatly enhanced if the agent produces propagules such as chlamydospores or sclerotia that are capable of persisting in the soil environment. Our research focuses on developing media and processes for the liquid culture production of promising fungal biocontrol agents. To demonstrate how nutritional factors can be used to regulate propagule formation and propagule "fitness" during liquid culture production, results from our studies with the mycoherbicide Colletotrichum truncatum and the mycoinsecticide Paecilomyces fumosoroseus will be presented. High concentrations of desiccation-tolerant, yeast-like blastospores of the fungus P. fumosoroseus were produced in liquid culture when supplied medium containing an appropriate concentration and source of nitrogen. Nutritional studies with C. truncatum cultures grown in liquid media demonstrated that sporulation or microsclerotia formation was regulated by the carbon concentration of the medium. High concentrations of desiccation-tolerant microsclerotia of C. truncatum were produced in liquid media that contained a high carbon concentration. The potential of using microsclerotia as soil amendments for controlling soil-born plant diseases was discussed.