Anaerobic disinfestation induced changes to the soil microbiome, disease incidence and strawberry fruit yields in California field trials

Soil-borne disease management in California strawberry production systems has historically relied upon pre-plant soil fumigation. Restricted efficacy of currently available fumigant chemistries towards certain pathogens and regulatory action requiring increased buffer zones has stimulated interest in development of alternative disease control strategies. Anaerobic soil disinfestation (ASD) demonstrates activity toward an array of soil-borne pathogens, however, there exist limited field-scale trials examining efficacy in strawberry systems. Multiple mechanisms, including the activity of an altered soil microbiome, are reported to function in ASD-induced disease suppression but consistency of the microbial response across soils has not been examined. The present research reports ASD-induced changes in composition of the soil microbiome which occurred in a carbon input-dependent manner and were consistent in two of the three field trials conducted. At all three field sites, ASD treatments that transformed the microbiome were consistently associated with enhanced strawberry yields, but specific compositional attributes of the microbiome in effective treatments were not uniform among all sites. Enhanced yields were associated with control of specific soil-borne pathogens at a given site, however disease control was not uniformly attained across all pathogens resident to a given soil system. Findings demonstrate that informed selection of substrate to be used in ASD and knowledge of the targeted pathogen profile resident to the strawberry field soil will be essential to successful use of ASD in commercial agricultural production settings.