Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: 9/26/2011
Publication Date: 10/30/2011
Citation: Gao, S., Qin, R., Cabrera, A., Hanson, B., Gerik, J.S., Wang, D., Browne, G.T. 2011. Application Of Low Permeability Tarp In Perennial Field Fumigation. International Conference on Methyl Bromide Alternatives and Emissions Reductions, San Diego, California, October 31-November 2, 2011. p. 74.1-74.4. Interpretive Summary: Successful replanting of orchards and vineyards and their nurseries still depend largely on soil fumigation for control of soil-borne pests, replanting diseases, and to meet the state’s Nursery Stock Nematode Control Program requirements in California. The increasingly used alternative fumigants to methyl bromide, 1,3-dichloropropene and chloropicrin, are highly regulated because of emissions that increase exposure risks and degrade air quality. Management strategies that minimize emissions and improve pest control efficacy are needed. Low permeability tarp, such as the totally impermeable film (TIF), is promising in this regard; but it also causes problems such as a surge in emissions upon tarp-cutting similar to standard PE tarp. Since fall 2009, we have conducted a series of field trials to test the TIF tarp performance in emission control and efficacy improvement as well as the potential of using reduced rates in broadcast application of Telone C35. Field data showed significant emission reduction (>90%) by TIF tarp compared to standard PE tarp. The intensity of the surge in emissions depends on fumigant concentrations retained under the tarp and in soil at tarp-cutting time. At the same application rate, higher fumigant concentrations under TIF (better efficacy) than under standard film in soil were determined. Reduced fumigation rates to half of full rate showed good efficacy; but differences in performance between tarps could not be concluded due to 100% kill of nematode in all fumigated treatments. This research continues to investigate reduced rates under TIF tarp and to collect field data/information for adoption of TIF tarp technology in soil fumigation for perennials.
Technical Abstract: Successful orchard replanting in many situations still depends on soil fumigation for control of soil-borne pests and replanting diseases in California. Additionally, perennial tree and grapevine nursery growers also depend on soil fumigation to meet the state’s Nursery Stock Nematode Control Program requirements. The main alternative fumigants to methyl bromide are 1,3-dichloropropene (1,3-D) and chloropicrin (CP); however, stringent regulations limit soil fumigant use because of emissions on exposure risks and air quality. Management strategies that minimize emissions and improve pest control efficacy are needed and the use of low permeability tarp, such as the totally impermeable film (TIF) is promising in this regard; but also exibited concerns such as a surge in emissions upon tarp-cutting. We have conducted a series of field trials since fall 2009 to test the TIF tarp performance in emission reduction and efficacy improvement as well as the potential of using reduced rates in broadcast application of Telone C35 under conditions applied for perennials. Field data showed significancly higher emission reduction (>95%) by TIF in comparison with standard PE film. Surges in emission were observed with intensity depending on fumigant concentrations under the tarp and in soil at tarp-cutting time. Generally higher fumigant concentrations under TIF than under PE film in soil profile were observed, i.e., higher concentration and time (CT) exposure indices under TIF tarp that is beneficial for better pest control. Reduced fumigant rates to half rate showed good efficacy although differences between different tarps are not evident due to 100% kill of nematode and variation among pests. Research continues for conclusions on the effects of reducing rates under TIF tarp on pest control. This research is collecting field data/information to help adoption of TIF tarp technology in soil fumigation for perennials.