2009 Annual Report
1a.Objectives (from AD-416)
To assess current and new soil fumigation methods for pest control efficacy, fumigant emissions and movement in the soil, and crop responses. An interdisciplinary team of USDA-ARS soil and weed scientists, UC and ARS nematologists and pathologists, and grower representatives will be collaborate on the following specific objectives:
1) To identify and characterize nematode, fungi, and weed species and population density before and at different times after soil fumigation,
2) To measure and describe fumigant movement in the soil in relation to soil depths from the depth of application,
3) To measure and characterize emission fluxes from the soil surface or through plastic tarps,
4) To obtain growth and yield parameters of replanted grape vines.
1b.Approach (from AD-416)
The overall goal of this research is to help growers transition from methyl bromide to alternative pest-management methodologies. This will be accomplished by developing new pest management practices that minimize fumigant emissions, control plant pests and maintain high crop production rates. The project will include studies of the film permeability, measurements of emission rate, measurements of plant pathogens in experimental treatments, and a determination of crop yield. Comparisons between numerous fumigation management pracices will be made. Laboratory and field experiments will be conducted to improve our understanding of the effect of soil properties, soil moisture, surface covers, termperature, and surface environmental conditions, etc. on the emission of fumigants from soil, and the effect on efficacy and crop yield. Completing this research will help growers transition from methyl bromide to alternative methodologies. Documents SCA with UC-Riverside.
Sealed permeability cells were used to collect data for determining the rate of mass transfer of methyl bromide, 1,3-dichloropropene, methyl iodide, and chloropicrin through various agricultural films used in the USDA-ARS Area Wide Project For Integrated Methyl Bromide Alternatives. Films were obtained by researchers in California and Florida and included samples from the roll and samples after installation in the field. The experiments included three replicates and several film permeability values have been obtained at three temperatures. This allows determination of the change in permeability with temperature using an Arrhenius equation. The experimental data has been converted to mass transfer coefficients using an analytical model which accounts for sorption to the film and diffusion through the film material. The analytical model has been incorporated into a Windows program to allow use by other interested individuals.
An Excel spreadsheet function was developed that performs the mass transfer coefficient calculation within Excel. This makes the analysis step much faster, simpler and less error prone. For detailed analyses, the Windows program allows visualization of the data and model in graphical form and provides error checking.
Research progress was monitored throughout the year from regular individual and group meetings, phone conversations, laboratory visits and email correspondence.