ABSTRACT
Cultural practices, including addition of organic amendments to soil, augment naturally occurring biological control of plant pathogens. Numerous reviews have summarized the beneficial effects of organic amendments on plant growth and disease control. This chapter explores the effects of organic amendments on soil-borne fungal diseases, and discusses the direct and indirect effects of organic amendments on the pathogen. It provides select examples of successful commercial use of amendments, and highlights some factors that affect disease control. Sometimes organic amendments result in undesirable effects such as increases in disease incidence. Most reported work on organic amendments has been done in the laboratory and greenhouse, rather than in the field. The overall effect of organic amendments in the biological control of soil-borne fungal pathogens include: reducing the inoculum density, suppressing disease although the pathogen population is not reduced, and preventing buildup of inoculum.
