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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #328677

Research Project: Integrated Strategies for Advanced Management of Fruit, Nut, and Oak Tree Diseases

Location: Crops Pathology and Genetics Research

Title: Effect of anaerobic soil disinfestation on the bacterial community and key soilborne phytopathogenic agents under walnut tree-crop nursery conditions

Author
item Strauss, Sarah
item Greenhut, Rachel
item McClean, Ali
item Kluepfel, Daniel

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2017
Publication Date: 1/16/2017
Citation: Strauss, S.L., Greenhut, R.F., Mcclean, A.E., Kluepfel, D.A. 2017. Effect of anaerobic soil disinfestation on the bacterial community and key soilborne phytopathogenic agents under walnut tree-crop nursery conditions . Plant and Soil. 415:493-506. doi:10.1007/s11104-016-3126-4.

Interpretive Summary: Anaerobic Soil Disinfestation (ASD) is a chemical-independent approach to managing soilborne phytopathogens. While it has been demonstrated that ASD can suppress phytopathogens in vegetable cropping systems, it has not been examined for control of tree-crop diseases under nursery conditions. Here we report on the potential of using ASD to manage soilborne populations of Agrobacterium tumefaciens and Pythium ultimum under walnut rootstock nursery conditions and compared the efficacy of ASD with the chemical fumigant Telone-C35.

Technical Abstract: Background and Aims: Anaerobic Soil Disinfestation (ASD) is a chemical-independent approach to manage soilborne phytopathogens. While it has been demonstrated that ASD can suppress phytopathogens in vegetable cropping systems, it has not been examined for control of tree-crop diseases. We examined the potential of ASD to manage soilborne populations of Agrobacterium tumefaciens and Pythium ultimum under walnut rootstock nursery conditions and compared the efficacy of ASD with the chemical fumigant Telone-C35. Methods: Mesh bags of sterile field soil inoculated with either A. tumefaciens or P. ultimum were buried in the first of two trials at 7.6 and 15.2 cm soil depths and in the second trial at 15.2, 45.7, and 76.2 cm soil depths prior to ASD or fumigation treatments. Bacterial rRNA was extracted from soils at these depths prior, immediately following ASD, and 4 months post-ASD to determine the effect of ASD on the bacterial community composition. Results and Conclusions: After one week of ASD, populations of both phytopathogens fell below detection limits at 7.6 and 15.2 cm soil depths. After completion of the six-week ASD treatment or 4-week fumigation period, populations of A. tumefaciens remained below detection limits at 7.6 and 15.2 cm depths and were not significantly different A. tumefaciens populations in the fumigation treatment. Agrobacterium tumefaciens populations also were significantly reduced, compared to no-treatment control soils, in both ASD and fumigation treatments at the 45.7 and 76.2 cm depths. Pythium ultimum populations dipped below detection limits after ASD treatment at 7.6 and 15.2 cm soil depths, and were significantly lower than no-treatment controls at the 45.7 cm depth. The bacterial community composition of ASD-treated soils also was significantly different as a function of soil depth, and the effect of ASD on the bacterial community composition persisted with time. The documented ASD-induced changes in the soilborne bacterial communities may have contributed to the population reductions observed for both A. tuemfaciens and P. ultimum.