Climate change is likely to alter the distribution and severity of soilborne diseases affecting both intensive and low-input agricultural production systems. Naturally occurring disease suppressive soils have been documented in a variety of cropping systems, and in many instances the biological attributes contributing to suppressiveness have been identified. While these studies have often yielded an understanding of operative mechanisms leading to the suppressive state, significant difficulty has been realized in the transfer of this knowledge into the development of effective field-level disease control practices. Early efforts focused on the inundative application of individual or mixtures of microbial strains recovered from these systems, and known to function in specific soil suppressiveness. However, the introduction of biological agents into non-native soil ecosystems typically fails to yield commercially viable or consistent levels of disease control. Of late, greater emphasis has been placed on manipulation of the cropping system to manage resident beneficial rhizosphere microorganisms as a means to suppress soilborne plant pathogens. One such strategy is the cropping of specific plant species or genotypes, or the application of soil amendments with the goal of selectively enhancing disease suppressive microbial communities. This chapter will briefly review the existence of biologically functional disease suppressive soils, document the research history supporting the potential in managing microbial communities for disease control, describe methods available for the effective manipulation of bioactive populations, and describe specific examples demonstrating the effective application of the approach.

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