Submitted to: San Joaquin Valley Grape Symposium
Publication Type: Proceedings
Publication Acceptance Date: January 7, 2009
Publication Date: January 7, 2009
Citation: Wang,D., B. Hanson, J. Gerik, S. Gao, and S. Vasquez. 2009. Vineyard soil fumigation-alternatives to methyl bromide. Proc. San Joaquin Valley Grape Symposium. Easton, CA, p.1-8. Interpretive Summary: Soil fumigation with either methyl bromide or Telone (1,3-dichloropropene or 1,3-D) is used by the grape growers in central California to control nematodes and other soilborne pests. Regulations are being developed and modified to limit total fumigant emissions (including 1,3-D) in townships, and require larger buffer zones to reduce potential exposure to farm workers and bystanders. More stringent regulations on fumigant emissions are likely to be issued in the near future to protect air quality. However, no emission information is available in the literature on 1,3-D and chloropicrin (CP) volatilization losses under grape replant situations. The project is part of the USDA-ARS Pacific Area-Wide Pest Management Program for Methyl Bromide Alternatives. The overall goal of this project was to determine, in grapevine replant situations, the needs and alternatives for soil fumigation with methyl bromide for effectively controlling plant pathogens and parasitic nematodes, lowering emission losses, and evaluating responses in vine growth. This is the second year of a five year project. Preliminary results showed nematode control in all fumigated plots, but not in the non-fumigated plots. Effective control was found for Pythium, but not for Fusarium (except in the methyl bromide treatment). Significant reductions in fumigant emissions were achieved with virtually impermeable films. Crop response in vine growth and yield will be measured in winter 2008-2009 and following years.
Technical Abstract: The use of methyl bromide is banned and soil fumigation with other chemicals also subjects to strict regulations to protect human health and air quality. Preplant soil fumigation is required in grape field to control nematodes and other soil-borne diseases. In central California, about 4,656 ha of wine grapes are replanted every year. Of this approximately 15% is fumigated, and 60% of this area is fumigated with methyl bromide. The objectives of this study were to (1) Identify and characterize nematode and fungi population density with different soil fumigation treatments, (2) Measure fumigant movement and distribution in the soil profile, (3) Measure emission fluxes from the soil surface or through virtually impermeable films (VIF) from current and new fumigation methods, and (4) Obtain growth and yield data from replanted grape vines. Eight treatments were devised and implemented in a randomized block design with three replications. Preliminary results indicate that 100% control was achieved in citrus nematodes in both the buried bags and the native soil in all the fumigated plots. Effective control was found for both Fusarium and Pythium in the surface 15 cm soil only in the methyl bromide treatment. Some short term control in Pythium was also observed with 1,3-D and CP treatment. The VIF tarp significantly reduced fumigant emissions in both the shank and the subsurface drip treatment. Vine pruning biomass and cane diameter will be measured winter 2008-2009.