Title: Management of resident soil microbial community structure and function to suppress soilborne disease development Author
Submitted to: CABI(Council of Applied Biology International, Oxford, United Kingdom
Publication Type: Book / Chapter
Publication Acceptance Date: July 21, 2009
Publication Date: June 7, 2010
Citation: Mazzola, M. 2010. Management of resident soil microbial community structure and function to suppress soilborne disease development. In: Reynolds, M., editor. Climate Change and Crop Production. CABI, Wallingford, UK. p. 200-219. Interpretive Summary: Soil ecosystems possess a wealth of biological resources that can be harnessed for use in control of plant diseases. Soils that naturally have low incidence of disease are commonly referred to as suppressive soils. Studies have been conducted to determine the properties of these soils that are important in this natural disease suppression, the goal being to identify those soil components that function to limit plant disease. Once the important disease-limiting components are identified, the hope would be to transfer these elements to other soils as a means to induce natural biological disease control. These studies demonstrated that growing wheat in orchard soils prior to planting apple, significantly depressed root infection by the fungal pathogen Rhizoctonia solani. It was shown that wheat suppressed this pathogen by enhancing populations of certain bacteria that are able to inhibit growth of R. solani. However, not all wheat varieties were able to reduce root infection by R. solani. It was shown that wheat cultivars that were best at providing disease control were the same cultivars that supported the highest populations of the bacterium Pseudomonas putida btp A. The ability to transform resident microbial communities in a manner which induces natural soil suppressiveness will have a significant role in environmentally sustainable systems for management of soilborne plant pathogens.
Technical Abstract: 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 bio-active populations, and a description of specific examples demonstrating the effective application of the approach.