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This project's long-term goals are: 1) to reduce the application rate of fumigation through a combination of extremely low permeability films (retention) and carbonation of the active ingredients (better dispersion) and 2) to ascertain the lowest fumigation rate required to be effective in a variety of soils with a variety of crops.<P> The expected outcome is an economically feasible alternative to Methyl Bromide that should reduce emissions, buffer zones, and the amount of fumigant per acre. The information generated will lead to training and adoption of new techniques for county extension agents, future scientists and educators, as well as other stakeholders.
Non-Technical Summary: <BR>The anticipated result is an economically feasible alternative to methyl bromide that should reduce: a) the amount of fumigant used per acre, b) emissions, and c) buffer zones, through a combination of soil sealing techniques and carbonation of the active ingredients. After the first year of the project, the information on the effectiveness of various carbonation levels in Dimethyl disulfide compared to nitrogen-propelled fumigants will go out to stakeholders such as growers, manufacturers, extension agents, government and pest control center personnel. The information will go out with the caveat that these are preliminary results. The second year of the project, the stakeholders will be informed of the aggregated results from testing the carbonated/ carbon dioxide-propelled dimethyl disulfide in multiple seasons. It is expected that local growers will continue the adaptation of this technology to their fields, especially in view of the fact that no equipment outlay is required for carbonating the dimethyl disulfide products. Feed back from the local growers will allow fine-tuning of the alternative system to be incorporated into the final report. The final report will include warnings of any possible hazards and limitations with the new system and improvement options. <P> Approach: <BR> Field site and chemicals. Commercial Dimethyl Disulfide will be obtained from Arkema, Inc. (Philadelphia, PA). Anasorb charcoal sampling tubes will be used to trap dimethyl disufide. The field site used for this study was located at the Plant Science Research and Education Unit, University of Florida about 35 km south of the university campus. Soil at this site is classified as Arredondo fine sand. Plots and fumigant treatment. Raised beds (0.9 m by 10 m) will be established in area known to exhibit nematode and nutsedge pressure. For the first trial, chisel injection of "Paladin" will be done at a depth of 20 cm using the full rate of 32 gallons per acre with N2, and one-third rate of 11 gallons per acre with N2 and CO2. The Paladin dispersed with CO2 will be carbonated at ambient temperature for 18 hours at 50 psi through the fumigant tank's siphon tube and applied 48 hours later. Control beds with no fumigation will be established concurrently. All plots will have 4 replicates using random block design. Plots will either be covered by Totally Impermeable Film "VaporSafe" (Raven Plastics, Sioux Falls, SD) or Virtually Impermeable Film "Blockade" (Berry Plastics, Evansville, IN). Sampling. For sampling soil pore air, a set of stainless steel gas probes (1, 5, 10, 20, 30, 40, and 60 cm) will be installed length-wise in the middle of each bed. In addition, six more 20-cm long gas probes were installed every 10 cm perpendicular from the center 20 cm probe to span the width of each bed. Thirty-five mL of soil pore air will be withdrawn from the probes with dimethyl disulfide in the air samples trapped by the charcoal sampling tubes. A stainless steel surface air collection pan will be placed on the surface of selected beds for determination of surface flux of dimethyl disulfide. Fifty mL surface air in the pans will be collected at 15 minutes intervals for a period of 60 minutes with dimethyl disulfide in the air samples trapped by Anasorb charcoal. Analysis. Dimethyl disulfide in the Anasorb charcoal tubes collected from soil pore and surface air will be analyzed by GC equipped with ECD after extraction by 5 mL hexane with 5 minutes shaking. Evaluation of Education and Extension Activities Extension and education activities will be evaluated based on the following criteria: 1) number of extension leaflets and articles issued through California and Florida state offices, 2) number of monographs published through "eXtension" website (http://www.extension.org/), 3) number of "hits" on the internet via the University of Florida's "EDIS" system, 4) number of students attending classes wherein the research material is presented, 5) number of refereed articles published in scientific journals, 6) number of grower tips based on the research that are published in the growers' newsletters, 7) number of products and growers' associations that feature these research results on the websites, and finally, 8) the number of manufacturers and pesticide registrants that offer new and improved products based on this research.