|Hewavitharana, Shashika - Washington State University|
|Shennan, Carol - University Of California|
|Muramoto, Joji - University Of California|
Submitted to: International Journal of Fruit Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2016
Publication Date: 7/20/2016
Citation: Mazzola, M., Hewavitharana, S., Strauss, S.L., Shennan, C., Muramoto, J. 2016. Anaerobic soil disinfestation and Brassica seed meal amendment alter soil microbiology and system resistance. International Journal of Fruit Science. doi: 10.1080/15538362.2016.1195310. Interpretive Summary: Soil-borne disease management without chemical fumigants remains a major challenge for many crop production systems including strawberry and tree fruits. Anaerobic soil disinfestation (ASD) and Brassica seed meal (SM) soil amendments have demonstrated promise as an alternative to soil fumigation for the control of soil-borne diseases. ASD involves the generation of an anaerobic environment through a combination of flooding and addition of a carbon source to the soil system. Brassica SM amendment can provide disease control through both chemical and biological means. The current studies demonstrated that both disease control measures suppress the activity of plant pathogenic organisms through multiple mechanisms. Production of volatile chemistries in response to both ASD and Brassica SM amendment can suppress certain pathogens, however our findings demonstrate that soil biology can play an important role as well. In fact, suppression of certain diseases, including Fusarium wilt of strawberry, appears to rely predominant on enhanced activity of certain bacteria in ASD-treated soils. In apple, long-term suppression of plant pathogens in response to Brassica SM pre- soil amendment was associated with the persistence of a distinctive microbial community associated with apple roots, and included microorganisms known to parasitize plant pathogenic organisms. These alternative treatments promote a soil biological community that is more resilient to re-infestation by plant pathogenic organisms and may provide a more sustainable alternative to the use of fumigants for the control of soil-borne diseases.
Technical Abstract: Brassica seed meal amendments and anaerobic soil disinfestation control a spectrum of soil-borne plant pathogens via a diversity of mechanisms. Transformations in microbial community structure and function in certain instances were determinants of disease control and enhanced plant performance. For instance, in strawberry field soils, carbon-source dependent efficacy of ASD was associated with increased abundance of bacteria in phylum Bacteroidetes; specific genera of which are known to provide biological disease control. Brassica seed meal amendment resulted in development of a soil system suppressive towards disease incited by the root pathogen Macrophomina phaseolina. Brassica seed meal treated orchard soil systems exhibit resistance to re-infestation by soil-borne pathogens, including the plant parasitic nematode Pratylenchus penetrans. System resistance is associated with significant and prolonged changes in rhizosphere microbiology and specifically amplification of specific organisms with potential to parasitize P. penetrans.