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The goals of this project are threefold: (1) to build on previous efforts and further develop Anaerobic Soil Disinfestation (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 research station and on-farm trials with production of a variety of economically important crops in Tennessee (TN), Florida (FL), and California (CA) in order to facilitate adoption of ASD by US growers, especially those who currently utilize either critical use exemption (CUE) or quarantine and preshipment (QPS) methyl bromide (MeBr).<P> To meet these goals, we have seven objectives: (1) determine the relationships between cumulative anaerobicity/Eh under different temperature regimes and treatment length, and control of pathogens, nematodes, and weeds, (2) further improve the efficacy of ASD in CA and reduce site to site variability in disease suppression , (3) evaluate the effect of tarp permeability and color on ASD treatment in order to determine the most economical and efficacious tarp for ASD application, (4) evaluate flat applications of ASD for cut flower production, (5) establish on-farm trials to demonstrate and evaluate on-farm implementation of ASD, (6) compare the economic feasibility of optimized ASD with MeBr fumigation, and (7) transfer ASD technology through education and extension programs and evaluate project outcomes. <P>We anticipate that ASD will be an effective and economic alternative to MeBr, with the potential to reduce fumigant use on a significant amount of farmland across the country. In practical terms ASD requires little modification to current practices, and unlike many biologically-based alternatives, we expect that ASD will effectively deal with multiple pest problems, as do chemical fumigants. We will work with interested growers to test and adapt the system themselves, and follow up on its performance. Using this adaptive management approach we estimate a timeline for significant commercial adoption of 4 to 6 years. <P>Major environmental benefits can accrue from this project based on realized reductions in the use of MeBr and other chemical fumigants.
Non-Technical Summary: 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. <P> Approach: To develop survival curves versus cumulative anaerobicity for key pathogen, plant-parasitic nematode, and weed species, a series of studies will be established in pots in climate-controlled growth chambers. Survival of pathogens, nematodes, and weeds will be regressed against cumulative anaerobicity below 200mV (mV hr) to determine the level needed during Anaerobic Soil Disinfestation (ASD) treatment for pathogen, weed, and nematode control at differing temperature regimes. To address past variability in CA results, we will do further pot experiments (varying temperature and tarping time) and field/on-farm tests with different dates and tarping times to better identify relationships between time, temperatures, Eh, and disease and weed suppression. We propose to a) select fields with high disease pressure for on-farm studies, and b) modify the burial-retrieval methods by using alfalfa leaves infested with Verticillium dahliae as inoculum, rather than infested soil; and compare the methods. Field trials will also be established which will implement ASD treatment technology across several different tarp types and determine impacts on the effectiveness of ASD treatments. An on-farm trial will be established on a commercial tomato farm in Grainger County, TN for two years to evaluate large-scale, on-farm applications of ASD in comparison with grower standard methyl bromide (MeBr) fumigation. The most promising combination of treatments will be determined from small-scale greenhouse and research farm trials. Treatments will be implemented with two separate, replicated fumigated controls included for comparison: a MeBr standard and a metam sodium standard. An on-farm trial will be established in Zolfo Springs, FL to evaluate large-scale, on-farm implementation of ASD for production of ornamentals. Treatments will include a MeBr standard for comparison. The economic feasibility of ASD will be determined using data collected from field studies, a simulation model of actual grower operations under varying management practices (CA), and a marginal approach using partial budgeting techniques (TN, FL). The estimated net returns to each of the management options for each location and farm size will be calculated under a range of price scenarios to test for economic feasibility and to compare the profitability of the alternatives under various circumstances. Results will be disseminated using a combination of site visits, electronic team meetings, on-farm and Research and Education Center field days, grower meetings, on-farm demonstrations, distribution of newsletters and research briefs, maintenance of an interactive project website, workshops, and publications in scientific and popular literature including grower magazines. Education objectives will be met through incorporation of research site visits and results into undergraduate/graduate courses and the training of graduate and undergraduate students in ASD technology.