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The University of Tennessee Institute of Agriculture
vegetable production

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Anaerobic Soil Disinfestation

Current Research Projects

 

Butler, D.M., C. Shennan, E.N. Rosskopf, J. Muramoto, S. Koike and K.A. Klonsky. Advanced development and implementation of anaerobic soil disinfestation as an alternative to methyl bromide. USDA-NIFA Methyl Bromide Transitions Program. 1 Sep 2010 31 Aug 2014.

Anaerobic soil disinfestation (ASD), a non-chemical alternative to soil fumigation with methyl bromide (MeBr), was developed in Japan and the Netherlands where it is used to control soilborne pathogens and nematodes in strawberries and vegetables. The ASD system can be utilized in urbanized areas where buffer restrictions would limit the applicability of alternative fumigants and, unlike many other biologically-based alternatives, has a broad-spectrum of activity, impacting most pests that are currently controlled by MeBr:chloropicrin combinations. This work will allow transfer of this promising technology to multiple cropping systems in many geographic locations and across differing soil types and environmental conditions in the United States. In a previously funded project, we confirmed the potential of ASD in Florida vegetable and coastal California strawberry production. To further that work, the goals of this project are threefold: (1) to build on previous efforts and further extend ASD for broad-spectrum control of soilborne pathogens, plant parasitic-nematodes, and weeds; (2) to gather additional data in tightly-controlled experiments to allow ASD to be effectively modeled and implemented across diverse local environmental conditions, production systems, and available inputs; and (3) to demonstrate the effectiveness of ASD in commercial-scale demonstration trials with production of a variety of economically important crops in Tennessee, Florida, and California to facilitate adoption of ASD by US growers who currently utilize MeBr under critical use and quarantine and preshipment allowances. To meet these goals, a team of multidisciplinary researchers and extension specialists from multiple institutions will work with grower advisory groups on project design, data interpretation, and grower implementation and outreach.

 

Butler, D.M., E.N. Rosskopf and B.H. Ownley. Overcoming obstacles to adoption of anaerobic soil disinfestation. USDA-NIFA Methyl Bromide Transitions Program. 1 Sep 2012 – 31 Aug 2015.

There is a critical need for economically-feasible soil fumigant alternatives that will provide vegetable, strawberry, and ornamental growers, who currently depend on the broad-spectrum soil fumigant methyl bromide, with a sustainable alternative to chemical soil fumigants. This is especially true due to the stringent regulatory restrictions with which these materials must be applied, as well as the current limitations of existing chemical alternatives to methyl bromide. An alternative approach to soil disinfestation, known as anaerobic soil disinfestation (ASD) involves the addition of an easily-decomposable carbon source to the soil (to stimulate microbial growth and respiration), tarping with plastic to limit gas exchange, and irrigation to saturation of the topsoil (or raised-bed) to provide adequate moisture for microbial growth, allow for transport of decomposition by-products through the soil solution, and to limit soil oxygen. The ASD approach to soil disinfestation can be used near residential and other sensitive areas where buffer restrictions would limit the use of chemical fumigants. ASD does not present any worker safety concerns outside of those typically associated with agricultural production, and due to the potential for use of locally-available organic wastes as carbon sources, ASD is considered more economically and environmentally sustainable. The short-term goal addressed in this proposal is to overcome the grower-identified obstacles that hinder the adoption of anaerobic soil disinfestation by growers in Tennessee, Florida, and other southeastern states. To meet this goal, we have the following four objectives: (1) evaluate and optimize the carbon to nitrogen ratio of soil amendments used in ASD to maintain pathogen, nematode, and weed control as well as to improve crop performance following ASD treatment, (2) evaluate food safety concerns related to the use of partially-composted animal manures as augmentative ASD amendments and evaluate alternative nitrogenous amendments for ASD treatment, (3) determine if ASD treatment can be improved through the addition of organic acids with treatment irrigation, and (4) provide immediate solutions to conventional commercial growers who want to adopt long-term sustainable solutions by outreach to growers, industry personnel, and fellow researchers through replicated on-farm demonstrations, extension presentations and publications, journal publications, economic analysis, and online publications.

 

U. Shrestha, Butler, D.M. and B.H. Ownley. Assessment of beneficial microorganisms: Trichoderma, Actinomycetes, and Bacillus in anaerobic soil disinfestation (ASD). USDA-SARE (Graduate Student Grant). 1 Sep 2014 –31 Aug  2015.

Studies on anaerobic soil disinfestation (ASD), a non-chemical alternative to soil fumigants for controlling many soilborne diseases, have shown that it enhances populations of beneficial microorganisms against plant pathogens, including increased presence of the biocontrol agents Trichoderma and actinomycetes as sclerotial parasites of Sclerotium rolfsii. However, studies on ASD effectiveness paired with beneficial microbes application are lacking. The proposed study will isolate two biocontrol agents from ASD-treated soils, Trichoderma and actinomycetes, and compare the effect of inoculation of these organisms at the initiation of ASD treatment separately and in combination on treatment effectiveness against the S. rolfsii pathogen. The study will be performed in pots with treatments factorially combined with two C rates (2 and 4 mg C/g of soil) and arranged in a completely randomized design in an environmentally-controlled growth chamber. As there is increasing need to optimize rates of C in soil amendments for effective ASD treatment, we will also analyze the effect of ASD C amendment rates on populations of biocontrol agents. While there is some research on effect of ASD on bacterial communities, studies on ASD impact on beneficial fungal populations are lacking. Hence, with the application of molecular techniques, the 16S-23S (bacterial) or 18S (fungal) ribosomal DNA will be amplified and sequenced for phylogenetic analysis of Trichoderma , actinomycetes and Bacillus populations. If successful, our results will contribute to the development of more effective ASD treatment methods for control of soilborne plant pathogens for vegetable and small fruit growers in the southeast. The objectives of the project are: 1. Determine the impact of Trichoderma and actinomycetes against sclerotia of S. rolfsii in ASD with different C rates at ranges of C:N ratios.  2. Evaluate the effect of ASD amendment carbon sources on populations of Trichoderma, actinomycetes and Bacillus.